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Pipe Schedule Calculator — NPS, Dimensions, Weight & Properties (ASME B36.10M)

Instantly lookup pipe dimensions, wall thickness, ID, weight, and flow area for any NPS and schedule per ASME B36.10M & B36.19M. Imperial & Metric.
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The Pipe Schedule Calculator provides instant access to standard pipe dimensions, weights, and properties for all Nominal Pipe Sizes (NPS) and schedules according to ASME B36.10M (Carbon Steel) and B36.19M (Stainless Steel).

Select NPS and Schedule to get Outside Diameter (OD), Inside Diameter (ID), Wall Thickness, weight per foot (lb/ft or kg/m), cross-sectional flow area, and internal volume. Supports both imperial and metric units with advanced calculations including moment of inertia, section modulus, and corrosion-adjusted properties.

Perfect for piping designers, estimators, procurement teams, and field engineers.

⚙️ Engineering Tool

Pipe Schedule Calculator

Instantly find OD, ID, wall thickness, weight & flow area for any NPS and pipe schedule. Based on ASME B36.10M & B36.19M standards.

ASME B36.10M ASME B36.19M Imperial & Metric Sch 5 – XXS
🔧
Pipe Lookup — NPS & Schedule
NPS is nominal — actual OD differs
⚙️
Weight & Volume — Extended Calculation
ft (enter pipe run length)
in (adds to required thickness)
for Bill of Materials
$/lb — leave blank to skip
💥
Pressure Reference (Barlow's Formula)
This is a reference calculation only. For code-compliant pressure design, use ASME B31.3 with your Pipe Wall Thickness Calculator.
psi — e.g. 20,000 psi for A106 Gr.B
⚖
Schedule Comparison — All Schedules for Selected NPS

Select an NPS to see all available schedules side-by-side. The currently selected schedule is highlighted.

Click "Build Comparison Table" after selecting NPS and Schedule on the Lookup tab.
🧮
Formulas Used in Calculations
1. Inside Diameter (ID)
\[ ID = OD - 2 \times t \]

Where OD = Outside Diameter, t = Wall Thickness. Both values from ASME B36.10M/B36.19M tables.

2. Pipe Weight per Unit Length (Imperial)
\[ W = 10.69 \times (OD - t) \times t \quad \text{[lb/ft, steel]} \]

Standard formula per ASME for carbon steel density (0.2836 lb/in³). For other materials the density factor is adjusted.

3. Pipe Weight per Unit Length (Metric)
\[ W = 0.02466 \times (OD - t) \times t \quad \text{[kg/m, steel]} \]

Where OD and t are in mm. Density = 7850 kg/m³.

4. Cross-Sectional Flow Area
\[ A = \frac{\pi}{4} \times ID^2 \]
5. Internal Volume per Unit Length
\[ V = A \times L = \frac{\pi}{4} \times ID^2 \times L \]

Converted to gal/ft (÷ 231 in³/gal) or L/m.

6. Moment of Inertia (I) — Structural
\[ I = \frac{\pi}{64} \times (OD^4 - ID^4) \]
7. Section Modulus (Z)
\[ Z = \frac{\pi}{32} \times \frac{(OD^4 - ID^4)}{OD} \]
8. Barlow's Formula — Max Allowable Pressure
\[ P_{max} = \frac{2 \times S \times E \times t}{OD} \]

Where S = allowable stress (psi), E = weld joint efficiency, t = wall thickness (in), OD = outside diameter (in). Reference only — use ASME B31.3 for design.

9. Pipe Schedule Number (Approximate)
\[ SCH \approx 1000 \times \frac{P}{S} \]

Where P = design pressure (psi), S = allowable stress (psi). Provides approximate schedule guidance.

10. Tolerance (ASME B36.10M)
\[ t_{min} = t \times 0.875 \qquad t_{max} = t \times 1.125 \]

Standard wall thickness tolerance is ±12.5% per ASTM A106/A53.

Accuracy Note: Dimensional data is based on ASME B36.10M (Carbon & Alloy Steel) and B36.19M (Stainless Steel) pipe dimension tables. Weight calculations use standard steel density of 0.2836 lb/in³ (7850 kg/m³). Actual pipe dimensions may vary slightly due to manufacturing tolerances. Always verify critical dimensions with mill certificates before fabrication or procurement.

🔗 Related Engineering Tools

Continue your piping calculations with these complementary tools:

📏 Pipe Wall Thickness Calculator 🔧 Flange Dimension Calculator ⚖️ Pipe Weight Calculator 💧 Flow Rate Calculator 🔩 Gasket Sizing Tool

📏 Complete User Guide

Pipe Schedule Calculator
— Full User Guide

A step-by-step walkthrough covering every formula, input, and output. Instantly find OD, ID, wall thickness, weight, and flow area for any NPS and pipe schedule — ASME B36.10M & B36.19M compliant.

ASME B36.10M ASME B36.19M Imperial & Metric Sch 5S – XXS Barlow’s Formula

1What Is a Pipe Schedule Calculator?

A pipe schedule calculator is an interactive engineering tool that instantly converts a Nominal Pipe Size (NPS) and a Schedule number (such as Sch 10, Sch 40, or Sch 80) into precise pipe dimensions — including Outside Diameter (OD), Wall Thickness (WT), Inside Diameter (ID), weight per unit length, flow area, and internal volume.

Rather than squinting through dense PDF tables from ASME B36.10M (carbon and alloy steel) or ASME B36.19M (stainless steel), this online pipe dimension calculator eliminates manual lookup errors and delivers accurate, engineering-grade results in real time — in both imperial (inches, lb/ft) and metric (mm, kg/m) units.

ℹ️ Key distinction: A pipe schedule calculator is a dimensional reference tool. It retrieves standardized OD/WT/ID values from ASME tables. A pipe wall thickness calculator computes the minimum required thickness for a given pressure using Barlow’s formula — that is a separate (but related) engineering calculation.
🏭 Who Uses This Tool?
  • Process & mechanical engineers
  • Pipefitters & fabricators
  • Procurement & estimating teams
  • HVAC & plumbing designers
  • Oil & gas / petrochemical engineers
  • Students & piping designers
📊 Standards Covered
  • ASME B36.10M — Carbon & alloy wrought steel pipe
  • ASME B36.19M — Stainless steel pipe (“S” schedules)
  • ASTM A53 / A106 Grade B (carbon steel)
  • ASTM A312 TP304/316 (stainless steel)
  • Schedule designation: 5S, 10, 40, 80, 160, XXS

2Key User Pain Points & How This Calculator Solves Them

Engineers, contractors, and procurement officers face recurring frustrations when working with pipe dimensions. Here is how this interactive pipe schedule calculator directly addresses each pain point:

📄
✖ Table Fatigue

Searching massive 20-column PDF pipe schedule charts for one decimal takes minutes — and errors happen.
✔ Instant lookup by NPS + Schedule. Results in under 2 seconds.

🌀
✖ NPS vs. Actual OD Confusion

For pipes above NPS 12, nominal size no longer matches the actual OD — causing costly ordering mistakes.
✔ Shows actual OD alongside nominal size every time.

⚖️
✖ Sch 40 vs. 40S Confusion

“Schedule 40” (carbon steel, B36.10) and “Schedule 40S” (stainless, B36.19) are identical in some sizes — but not all.
✔ Standard toggle (B36.10 / B36.19) prevents mix-ups.

📏
✖ Manual Unit Conversion

Converting pipe dimensions from inches to mm mid-project introduces calculation errors on international projects.
✔ One-click toggle converts all outputs instantly.

⚖️
✖ Separate Weight Calculator Needed

Calculating pipe weight for shipping / BOM requires a separate tool or manual formula application.
✔ Built-in weight calculator — enter length and get total weight instantly.

💧
✖ Flow Area Needed Separately

Fluid flow calculations require the pipe internal cross-sectional area — not shown in standard schedule charts.
✔ Flow area and internal volume calculated automatically from ID.

3Understanding the Inputs: NPS, Schedule & Material

3.1 — Nominal Pipe Size (NPS)

The Nominal Pipe Size (NPS) is a North American standard for pipe sizing. It is a dimensionless designator — for sizes up to NPS 12, the nominal number is close to (but not equal to) the actual outside diameter in inches. For NPS 14 and above, the nominal size equals the actual OD in inches.

⚠️ Common mistake: Engineers sometimes use NPS as the actual pipe OD. This is only true for NPS 14+. For NPS 2, the actual OD is 2.375" — not 2". Always verify OD from the ASME table.
NPS (in)Actual OD (in)Actual OD (mm)OD = NPS?
1/20.84021.34✘ No
22.37560.33✘ No
66.625168.28✘ No
1212.750323.85✘ No
1414.000355.60✔ Yes
2424.000609.60✔ Yes

3.2 — Pipe Schedule (Wall Thickness Designator)

The pipe schedule is a standardized wall thickness designation. A higher schedule number means a thicker wall and therefore a smaller inside diameter for the same NPS. Schedule directly affects pressure rating, weight, and flow capacity.

ScheduleStandardTypical UseNotes
5S / 10SB36.19MLow-pressure stainlessThin wall, light service
STD / 40B36.10MGeneral plumbing, HVACCommonly stocked
40SB36.19MStainless equivalent of STDSame as STD for most NPS
XS / 80B36.10MMedium pressure, steamCommonly stocked
80SB36.19MStainless XS equivalent
160B36.10MHigh-pressure systemsHeavy wall
XXSB36.10MVery high pressureThickest standard wall

3.3 — Material Selection & Density

Pipe material affects weight calculations because different materials have different densities. The calculator adjusts weight per unit length based on the selected material:

MaterialDensity (lb/in³)Density (g/cm³)Common Standard
Carbon Steel0.28367.85ASTM A53 / A106
Stainless 3040.28907.99ASTM A312 TP304
Stainless 3160.29008.02ASTM A312 TP316
PVC0.05201.44ASTM D1785
Copper0.32408.96ASTM B88

4Visual Diagram: OD, ID & Wall Thickness Explained

The diagram below shows the physical relationship between the three core pipe dimension parameters for a NPS 4, Schedule 40 pipe (OD = 4.500", WT = 0.237", ID = 4.026"). The pipe cross-section ring represents the steel wall — the hollow center is the flow bore.

PIPE CROSS-SECTION DIAGRAM NPS 4 • Schedule 40 • Carbon Steel (ASME B36.10M) OD = 4.500" ID = 4.026" WT = 0.237" STEEL WALL FLOW BORE DIMENSION SUMMARY Outside Diameter (OD) 4.500" 114.30 mm Inside Diameter (ID) 4.026" 102.26 mm Wall Thickness (WT) 0.237" 6.02 mm Weight: 10.79 lb/ft • 16.07 kg/m Flow Area: 12.73 in² • 8,213 mm²

📏 Diagram not to scale. Wall thickness is exaggerated for clarity. Values from ASME B36.10M, NPS 4, Schedule 40, Carbon Steel.

5All Formulas Used — With Worked Examples

The pipe schedule calculator uses the following engineering formulas to compute all outputs. Each formula is shown below with variable definitions, units, and a worked example using NPS 2, Schedule 40 (OD = 2.375", WT = 0.154").

Formula 1: Inside Diameter (ID)

Inside Diameter
ID = OD − 2 × t
Where: OD = Outside Diameter (in or mm) | t = Wall Thickness (in or mm)
🧮 Example: ID = 2.375 − 2×0.154 = 2.067" (52.50 mm)

The inside diameter is the actual flow bore of the pipe. It is critical for velocity, pressure drop, and Reynolds number calculations. Note that a higher schedule number means a thicker wall and therefore a smaller ID for the same NPS.

Formula 2: Pipe Weight per Unit Length (Imperial)

Weight per Foot — Steel (Imperial)
W = 10.69 × (OD − t) × t   [lb/ft]
Constant 10.69 derived from: 12 in/ft × π × density (0.2836 lb/in³) ≈ 10.69 | For other materials, the density factor adjusts proportionally.
🧮 Example: W = 10.69 × (2.375−0.154) × 0.154 = 3.653 lb/ft

Formula 3: Pipe Weight per Unit Length (Metric)

Weight per Meter — Steel (Metric)
W = 0.02466 × (ODmm − tmm) × tmm   [kg/m]
Where OD and t are in millimeters. Density = 7850 kg/m³.
🧮 Example (NPS 2, Sch 40): W = 0.02466 × (60.33−3.91) × 3.91 = 5.44 kg/m

Formula 4: Cross-Sectional Flow Area

Internal Flow Area
A = (π ÷ 4) × ID²
Result in in² (imperial) or mm² (metric). Used for fluid velocity and flow rate calculations.
🧮 Example: A = (π/4) × 2.067² = 3.356 in²

Formula 5: Internal Volume per Unit Length

Internal Volume per Foot / Meter
V = A × L = (π ÷ 4) × ID² × L
To convert in²/ft to gal/ft: multiply area (in²) × 12 ÷ 231. For metric: result in liters/meter (L/m).
🧮 Example: V = 3.356 in² × 12 ÷ 231 = 0.1743 gal/ft

Formula 6: Moment of Inertia (Structural Applications)

Moment of Inertia — Pipe Ring
I = (π ÷ 64) × (OD⁴ − ID⁴)
Result in in⁴ (imperial) or mm⁴ (metric). Used for pipe support span calculations and structural analysis.
🧮 Example (NPS 2, Sch 40): I = (π/64) × (2.375⁴ − 2.067⁴) = 0.6658 in⁴

Formula 7: Section Modulus (Bending Stress)

Section Modulus
Z = (π ÷ 32) × (OD⁴ − ID⁴) ÷ OD
Result in in³. Section modulus determines the pipe’s resistance to bending. Higher Z = more bending resistance.
🧮 Example: Z = (π/32) × (2.375⁴ − 2.067⁴) ÷ 2.375 = 0.5612 in³

Formula 8: Maximum Allowable Pressure (Barlow’s Formula)

Barlow’s Formula — Maximum Allowable Pressure
Pmax = (2 × S × E × t) ÷ OD
S = Allowable stress (psi) | E = Weld joint efficiency (1.0 seamless, 0.85 ERW) | t = Wall thickness (in) | OD = Outside diameter (in)
🧮 Example (NPS 2, Sch 40, A106 Gr.B, seamless): P = (2×20000×1.0×0.154) ÷ 2.375 = 2,591 psi
⚠️ Reference only. Barlow’s formula provides a quick pressure estimate. For code-compliant pressure design, use ASME B31.3 (process piping) or B31.1 (power piping) with the full design equation including temperature derating and corrosion allowance.

Formula 9: Schedule Number (Approximate)

Approximate Schedule Number
SCH ≈ 1000 × (P ÷ S)
P = Design pressure (psi) | S = Allowable stress (psi)
🧮 Example: P = 1500 psi, S = 20000 psi → SCH ≈ 1000 × (1500/20000) = 75 → Use Schedule 80

Formula 10: Manufacturing Wall Thickness Tolerance

ASME B36.10M Tolerance (±12.5%)
tmin = t × 0.875    |    tmax = t × 1.125
Pipe mills are permitted a −12.5% under-tolerance on wall thickness per ASTM A53/A106. This must be factored into pressure design.
🧮 Example (WT = 0.154"): t_min = 0.135" | t_max = 0.173"

6Pipe Schedule Chart: ASME B36.10M vs B36.19M

The table below is a quick-reference pipe schedule chart for commonly used sizes. OD and wall thickness are shown in inches. Use the calculator above for instant metric conversion and derived properties.

ℹ️ B36.10M vs B36.19M: For sizes NPS 12 and below, Schedule 40 (B36.10) and Schedule 40S (B36.19) often have the same dimensions. For NPS 14 and above, “S” schedules may differ. Always specify the standard when ordering.
NPS (in) OD (in) Sch 40 / 40S Sch 80 / 80S Sch 160
WT (in)ID (in) WT (in)ID (in) WT (in)ID (in)
1/20.8400.1090.6220.1470.5460.1880.464
11.3150.1331.0490.1790.9570.2500.815
22.3750.1542.0670.2181.9390.3441.687
44.5000.2374.0260.3373.8260.5313.438
66.6250.2806.0650.4325.7610.7195.187
88.6250.3227.9810.5007.6250.9066.813
1010.7500.36510.0200.5949.5621.1258.500
1212.7500.40611.9380.68811.3741.31210.126

7Step-by-Step: How to Use the Pipe Schedule Calculator

Follow these steps to get accurate pipe dimension results from the calculator tool above:

  • 1
    Select Unit System & Standard
    Toggle between Imperial (in / lb/ft) or Metric (mm / kg/m) using the unit bar at the top. Select ASME B36.10 for carbon steel or ASME B36.19 for stainless steel pipe. This affects which schedule designations are available.
  • 2
    Choose Nominal Pipe Size (NPS)
    Select your pipe’s NPS from the dropdown (1/8" to 24"). Remember: NPS is not the actual OD. The calculator will show the correct OD automatically from ASME tables.
  • 3
    Select Pipe Schedule
    The Schedule dropdown auto-populates with only the schedules available for your selected NPS. Choose your schedule (e.g., Sch 40, Sch 80). A ✓ Commonly Stocked badge appears for Sch 40, 80, STD, and XS.
  • 4
    Select Material
    Choose material (Carbon Steel, Stainless 304/316, PVC, Copper, or Custom). This adjusts the weight calculation using each material’s density. OD and wall thickness are not affected — those come from ASME tables.
  • 5
    Click ⚡ Calculate
    Results appear instantly: OD, WT, ID, weight per length, flow area, internal volume, and mm equivalents. The SVG cross-section diagram updates to scale the wall thickness visually. Manufacturing tolerance (±12.5%) is shown below the results.
  • 6
    Use Advanced Tab for BOM & Pressure
    Switch to the Advanced tab to enter pipe length, corrosion allowance, quantity, and material cost. Get total weight, total volume, moment of inertia, section modulus, and estimated cost. The Barlow’s pressure reference section shows max allowable pressure for the selected schedule.
  • 7
    Compare All Schedules (Compare Tab)
    Click “Build Comparison Table” on the Compare tab to see all available schedules for your NPS side-by-side. Export as CSV for use in Excel or procurement systems.
  • 8
    Copy or Export Results
    Use 📋 Copy Results to copy a formatted text summary to your clipboard (for emails, reports, or Slack messages). Use 💾 Export CSV on the Compare tab to download a full schedule table for documentation or BOMs.

8Schedule 40 vs Schedule 80 — Side-by-Side Comparison

This is the most common question engineers face: when should I use Sch 40 vs Sch 80? The answer involves cost, weight, pressure rating, and corrosion resistance tradeoffs. The example below uses NPS 4, Carbon Steel.

Schedule 40 — NPS 4
4.500"
OD (fixed)
WT: 0.237"
ID: 4.026"
Weight: 10.79 lb/ft
Max Pressure: ~2,106 psi
Cost: Lower ✓
Flow Area: 12.73 in² ✓
VS
Schedule 80 — NPS 4
4.500"
OD (fixed)
WT: 0.337"
ID: 3.826"
Weight: 15.00 lb/ft
Max Pressure: ~2,993 psi
Cost: Higher
Flow Area: 11.50 in²
✅ When to choose Sch 80: Higher pressure systems, corrosive services (extra wall provides corrosion allowance life), threaded connections (thicker wall needed for thread engagement), and steam systems above 150 psi.
ℹ️ When to choose Sch 40: General service water, HVAC, low-pressure gas, and structural applications. Default choice for most standard piping. Lower weight reduces support loads.

Why Engineers Select Different Schedules for the Same Pressure

Even when Sch 40 meets the minimum pressure requirement, engineers sometimes specify Sch 80 for the same service. The key tradeoffs are:

ConsiderationSch 40 AdvantageSch 80 Advantage
CostLower material cost (less steel)—
Weight & SupportLighter — fewer/cheaper supports—
Pressure Safety Factor—Greater margin above design pressure
Corrosion Life—More wall available before retirement
Threaded JointsNot suitable for threading in larger sizesPreferred for threaded connections
Flow CapacityLarger ID → higher flow / less pressure dropSlightly reduced ID reduces flow area
Vibration Resistance—Stiffer wall handles vibration/fatigue better

9Common Mistakes When Selecting Pipe Schedules

Avoid these frequent errors that lead to procurement delays, design failures, or safety risks:

🚫
Mistake 1: Treating NPS as the Actual Outside Diameter
For NPS 1/2 to 12, the nominal size does NOT equal the actual OD. NPS 4 has an OD of 4.500", not 4". ✔ Fix: Always look up the OD from ASME B36.10M/B36.19M tables (or use this calculator).
🚫
Mistake 2: Confusing Schedule 40 (B36.10) with Schedule 40S (B36.19)
Sch 40 and 40S are identical for NPS 10 and below but can differ for larger sizes. Mixing them causes flange mismatch and bore incompatibility. ✔ Fix: Always specify the standard (B36.10 or B36.19) alongside the schedule.
🚫
Mistake 3: Ignoring the −12.5% Wall Thickness Mill Tolerance
ASME permits pipe mills to produce pipe with walls up to 12.5% under the nominal thickness. Using the nominal WT in pressure calculations without this deduction is non-conservative. ✔ Fix: Use t_min = nominal WT × 0.875 for all pressure design.
🚫
Mistake 4: Not Accounting for Corrosion Allowance
Selecting a schedule based only on initial pressure requirements without corrosion allowance leads to premature pipe retirement in corrosive services. ✔ Fix: Add your CA (typically 1.5–3mm) to the required wall thickness before selecting a schedule.
🚫
Mistake 5: Using Barlow’s Formula as a Design Code
Barlow’s formula gives a quick pressure estimate but does not include temperature derating, Y-coefficient, or weld efficiency factors required by ASME B31.3. ✔ Fix: Use Barlow’s for screening only. Confirm with the full ASME B31.3/B31.1 design equation.
🚫
Mistake 6: Using Pipe ID for Flange Bore Matching
Pipe ID changes with schedule, but flange bore is fixed for a given rating class. Selecting a heavy-wall schedule may create a bore mismatch at the flange face, causing flow turbulence and inspection failures. ✔ Fix: Cross-check pipe ID against the matching flange bore using the Flange Dimension Calculator.

10Accuracy Note & Disclaimer

Data Source: All dimensional data is sourced from ASME B36.10M (Welded and Seamless Wrought Steel Pipe) and ASME B36.19M (Stainless Steel Pipe) standards. Weight calculations use standard steel density of 0.2836 lb/in³ (7,850 kg/m³) adjusted proportionally for other materials.

Tolerance: Actual pipe dimensions may vary within manufacturing tolerances. Per ASTM A53/A106, nominal wall thickness carries a −12.5% under-tolerance. Minimum wall thickness = nominal WT × 0.875.

Pressure Calculations: Barlow’s formula results shown in the Advanced tab are reference estimates for initial screening only. They do not constitute a code-compliant pressure design. For ASME B31.3 / B31.1 compliance, consult a licensed professional engineer and apply the full design equation including temperature derating factors.

Limitation: This calculator covers ASME B36.10M and B36.19M schedules for standard NPS sizes from 1/8" to 24". For API 5L line pipe, ISO 4200, DIN 2448, or special dimensions, verify against the applicable standard.

11Frequently Asked Questions (FAQ)

A pipe schedule is a standardized designator that defines the wall thickness of a pipe for a given nominal pipe size (NPS). It is not a measure of the outside diameter — the OD is fixed for each NPS regardless of schedule. A higher schedule number means a thicker wall, smaller inside diameter, higher pressure rating, and greater weight. Common schedules include Sch 10, 40, 80, 160, and XXS. The system was developed by the American Standards Association (now ANSI/ASME) to create a consistent, industry-wide reference for pipe selection.
The approximate schedule number can be calculated using: SCH ≈ 1000 × (P ÷ S), where P = design pressure (psi) and S = allowable stress of the pipe material (psi). For example, at P = 1,000 psi and S = 20,000 psi: SCH ≈ 1000 × (1000/20000) = 50, so Schedule 60 or 80 would be selected. However, pipe schedule tables (ASME B36.10M) define the actual wall thickness — the formula gives only a guide for which schedule range to investigate.
Schedule 40 is the most commonly used pipe schedule for general-purpose piping. It represents a specific wall thickness for each nominal pipe size (NPS) as tabulated in ASME B36.10M. For NPS 2, Sch 40 has an OD of 2.375", a wall thickness of 0.154", and an ID of 2.067". The “40” itself does not directly represent a thickness value — it is simply a designation from the original ANSI B36.10 standard. Sch 40 is equivalent to STD (standard) wall for most sizes up to NPS 10.
Select your NPS and Schedule in the Pipe Schedule Calculator above and click Calculate. The wall thickness (WT) is read directly from the ASME B36.10M or B36.19M table for your specific NPS and schedule combination. You cannot calculate wall thickness from schedule number alone using a formula — the values are tabulated in the standard. The “schedule number” concept only approximates: actual thickness must always come from the ASME table.
DN (Diamètre Nominal, ISO/DIN metric designation) is the metric equivalent of NPS. Common conversions: NPS 1/2" = DN 15 | NPS 1" = DN 25 | NPS 2" = DN 50 | NPS 4" = DN 100 | NPS 6" = DN 150 | NPS 8" = DN 200 | NPS 12" = DN 300. DN and NPS are both nominal designators — neither equals the actual OD. The actual outside diameter in mm = OD(in) × 25.4. Use the Metric toggle in the calculator to see all values in mm automatically.
Use the formula: W (lb/ft) = 10.69 × (OD − t) × t for carbon steel, where OD and t (wall thickness) are in inches. This constant (10.69) is derived from π × 12 × density of steel (0.2836 lb/in³). For metric: W (kg/m) = 0.02466 × (OD mm − t mm) × t mm. Or simply enter your NPS, schedule, and material in this calculator — the weight is computed and displayed automatically, including total weight for your entered pipe length.
ASME B36.10M covers welded and seamless wrought steel pipe (carbon and alloy steel) and uses schedules without the “S” suffix (Sch 10, 40, 80, 160, etc.). ASME B36.19M covers stainless steel pipe and uses “S” schedules (5S, 10S, 40S, 80S). For most sizes up to NPS 12, Sch 40 (B36.10) and Sch 40S (B36.19) have identical wall thicknesses. Differences appear in larger sizes. Always specify the standard when ordering or detailing drawings to avoid ambiguity.
Barlow’s formula estimates the maximum allowable internal pressure for a given pipe: P = (2 × S × E × t) ÷ OD. You can reverse it to find the minimum required wall thickness: t = (P × OD) ÷ (2 × S × E). Then compare this against the ASME B36.10M table to find the lowest schedule whose wall thickness meets or exceeds the calculated minimum. Always add your corrosion allowance to the required thickness before selecting. Note: Barlow’s formula is a screening tool — code design per ASME B31.3 includes additional factors.

🔗 Related Piping Engineering Tools

Continue your calculations with these complementary tools in our piping engineering suite:

📏 Pipe Wall Thickness Calculator 🔧 Flange Dimension Calculator ⚖️ Pipe Weight Calculator 💧 Flow Rate Calculator 🔩 Gasket Sizing Tool 📌 Pipe Schedule Chart (PDF)

🔧 SteelSolver Engineering Tools & Guides — featuring 260+ free calculators and 60+ in-depth guides for engineers, fabricators, and metalworkers.

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