Rebar Sizes, Diameters, Grades, Weights, Cost & Transportation (with Complete Charts)

Everything you need to know about rebar, from sizes and diameters to grades and weights, all in one place, with US, metric, and Canadian standards explained

If you've ever stood at a steel yard squinting at a bundle of bars trying to figure out if that's a #4 or a #5, this is the guide you needed an hour ago. Rebar sizing seems like one of those things that should be simple, and it kind of is, but only once someone actually walks you through it.

I remember the first time I ordered rebar for a small footing job. I said "#4 bars, standard length" and felt pretty confident. Then the guy behind the counter asked me, "Grade 40 or Grade 60?" and I just stared at him like he'd asked me a question in another language. I guessed. Correctly, thankfully. But I spent the rest of that afternoon learning what I should've known before showing up.

So here's everything. Sizes, diameters, weights, grades, types, charts, cost, and transportation you'll actually use on a real job.

What Is Rebar?

Rebar means “reinforcing bar,” and it is a steel rod used inside concrete to add strength where concrete is weak. Concrete handles compression well, but it can’t deal with forces that pull it apart. Steel rebar fixes that problem.

Concrete might look tough, but it's a bit like a biscuit: strong when pressed but easy to snap. Steel, on the other hand, can stretch, bend, and hold tension. When you mix them, you get reinforced concrete.

Rebar usually has ribs, which grip the concrete. Smooth bars exist but are rarely used in structural work. Most people simply call it “steel rebar,” “reinforcement bar,” “reinforcement steel,” or even “TMT bar,” depending on the country.

You might hear unusual questions online, like “What is rebar in GPU or PC?”, but that's usually people mixing up terms. Rebar here has nothing to do with computers, BIOS, or Nvidia settings.

Quick Reference: Rebar Types, Sizes, and Grades

Category	Options	Typical Use / Notes
Types	Carbon Steel (Black Bar)	Most common, general-purpose reinforcement
	Epoxy-Coated Steel	Coastal areas, roads with salt, corrosion resistance
	Stainless Steel	High corrosion resistance, expensive, long-life projects
	GFRP (Glass Fiber Reinforced Polymer)	Non-corrosive, non-conductive, specialty applications
	TMT (Thermo-Mechanically Treated)	Strong, flexible, widely used in modern construction
Sizes	#3 (⅜ in / 10 mm)	Patios, driveways, swimming pools
	#4 (½ in / 12 mm)	Residential slabs, footings
	#5 (⅝ in / 16 mm)	Commercial walls, bridges
	#6 (¾ in / 20 mm)	Foundations, heavy beams
	#7 (⅞ in / 22 mm)	Columns, large infrastructure
	#8+ (1 in+ / 25 mm+)	High-rise buildings, heavy infrastructure
Grades	Grade 33	Light structures, low-load areas
	Grade 40	Driveways, residential slabs
	Grade 60	Most common in commercial/residential construction
	Grade 75	Bridges, dams, heavy-load structures
	Grade 80	Earthquake-prone zones, tunnels
	Grade 100	High-rise buildings, very high-strength applications

This table gives a quick chart of the most important info, so anyone can glance at it and understand which rebar to use for a project.

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Understanding Rebar Size

Rebar size is simply the measure of the bar’s diameter. In the metric system, it’s listed in millimeters, such as 10mm or 16mm. In the U.S., bars are labeled as #3, #4, etc.—each number corresponds to a certain diameter.

Why does size matter? Well, the bigger the bar, the more load it can carry. That’s why structural engineers spend hours deciding the right size. But here’s a little trick I learned: don’t just eyeball it. Even a 2mm difference can change your weight calculations significantly.

Some practical points:

• Load-bearing: bigger size = stronger bar.
• Spacing: larger bars need more room in concrete.
• Flexibility: small bars bend more easily for corners and small structures.

US Rebar Sizes: The Imperial Size Chart

The US system labels rebar by a number that equals the bar's diameter in eighths of an inch. So a #3 bar has a diameter of 3/8 inch. A #6 is 6/8, which reduces to 3/4 inch. Once you know that rule, you'll never need to guess again.

Sizes run from #2 to #18, though honestly, you'll see #3 through #8 on most jobs. The bigger stuff — #14 and #18 — shows up in bridges, dams, and large-scale infrastructure. I've never personally wrestled a #18 bar. From what I hear, it's more like wrestling a drainpipe.

Full US Imperial Rebar Size Chart

Source: ASTM A615/A706. Note: Sizes #9 and above follow area-based legacy measurements, not the eighth-inch rule.

Quick Match: US Bar to Common Use

You're probably wondering about those "soft metric" labels in the first table — #10, #13, #16, and so on. Those aren't separate sizes. They're just the metric name for the same bar, rounded to approximate diameter in millimeters. A #4 US bar and a #13 metric bar are identical. The labels are two countries calling the same thing by different names.

Metric Rebar Sizes: European Standard Chart

In the metric system, rebar size is simply the nominal diameter in millimeters. A 12mm bar is 12mm in diameter. No fractions, no eighths. Most people find this easier once they switch over.

European and international projects follow this convention. The bars go from 6mm up to 50mm and beyond for specialty structural work. Residential projects abroad lean heavily on 10mm and 12mm. Larger structural elements move into 16mm, 20mm, 25mm, and 32mm territory.

European Metric Rebar Size Chart

Weights calculated using the D²/162 formula. Density of steel = 7850 kg/m³.

I was eating a really good apple while I looked this up the first time, and I remember thinking — why can't steel be this simple? Turns out it almost is. The metric system at least makes the diameter obvious. T12 is 12mm. Done.

The one place people get confused is 12mm vs 13mm vs the #4 US bar. The #4 is actually 12.7mm in diameter, not exactly 12mm. Close enough for most applications, but worth knowing if you're mixing metric drawings with US bars on a jobsite.

Canadian Rebar: The CSA G30.18 Standard

Canada uses a designation system based on approximate area rather than exact diameter, which is unusual and catches a lot of people off guard. Bars are labeled 10M, 15M, 20M, 25M, and so on. The "M" stands for metric, and the number refers to the nominal area in mm² rounded to the nearest 100.

So a 10M bar isn't 10mm in diameter. It actually measures 11.3mm across. The number is about the area, not the thickness. Once you know that, the chart below will make a lot more sense.

Canadian Rebar Size Chart (CSA G30.18)

CSA G30.18 standard. Bar designations represent nominal area rounded to the nearest 5 mm².

If you're working on a cross-border project — say a structure designed in Canada but built by a US crew — this is where the paperwork gets interesting. A Canadian engineer spec'ing 15M bars isn't asking for 15mm bars. They want a bar with roughly 200mm² of cross-sectional area, which lands closest to a US #5. Know the system before you start ordering.

Rebar Weight Per Meter and Per Foot

Rebar weight matters for three things: structural engineering calculations, transportation costs, and ordering the right quantity without guessing. Get the weight wrong and you either overpay at the yard or run short mid-pour. Neither is fun.

The formula is simpler than it looks. For metric bars, weight in kg per meter equals D squared divided by 162. That's it. D is the diameter in millimeters. For a 12mm bar: 12 × 12 = 144, divided by 162 = 0.888 kg/m. Matches the chart exactly.

For imperial, the equivalent formula is W = 0.006165 × D², where D is in inches, and W comes out in pounds per foot. Most people don't use that one. They just check a table. Which is honestly the smarter move.

Common Metric Rebar Weight Chart

Weight calculated at steel density of 7850 kg/m³. Standard bar length is 12 meters in most markets.

US Imperial Weight Per Foot

One thing I didn't appreciate early on: rebar weight grows with the square of the diameter, not linearly. Go from 10mm to 20mm, and the weight doesn't double — it quadruples. That's why 40mm bars weigh nearly 10kg per meter while 20mm bars are under 2.5kg. Worth internalizing before you estimate a large pour.

How Rebar Weight Affects Construction Cost & Transportation Logistics

Rebar weight isn't just a number on a chart—it's a direct driver of your project budget. Heavier bars increase material costs (steel is sold by the ton), raise transportation expenses, demand larger crews or equipment for handling, and can even alter structural design requirements. Understanding this relationship helps you avoid overspending on unnecessarily heavy reinforcement.

How Weight Directly Impacts Material Cost

Because rebar is priced per ton or per kilogram, a heavier bar size always costs more for the same length. Using the weight table from earlier:

US Size	Weight (lb/ft)	Weight (kg/m)	Approx. Cost per 20-ft bar ($0.80/lb)
#4	0.668	0.996	$10.69
#5	1.043	1.556	$16.69
#6	1.502	2.240	$24.03

Switching from #4 to #6 on 100 bars adds over $1,300 in material cost alone—before delivery or labor.

Labor & Handling: Heavy Bars Slow You Down

Heavier rebar requires more workers, lifting equipment (cranes, hoists, forklifts), and longer installation time. A #4 bar can be carried and tied by one person; a #8 bar often needs two or three. Field experience shows that moving from #4 to #6 can increase crew size by 50% and double placement time for the same linear footage.

Example labor impact:

• 500 pieces of #4 rebar (20 ft each): 2 workers, 1 day.
• Same quantity of #6 rebar: 3 workers, 1.5 days.
• Extra labor cost at $30/hr: $1,200+.

Transportation Costs: The Hidden Expense of Heavy Rebar

Freight companies charge by weight (per ton or per kg) and distance. Heavier shipments cost more to move—but volume-to-weight ratio, fuel prices, and load optimization also matter.

Basic formula:

Transport Cost = Total Weight (tons) × Rate per ton per km × Distance (km)

Example:

• 10 tons of #5 rebar, rate = $0.30/ton/km, distance = 200 km
  → 10 × 0.30 × 200 = $600

If you need 20 tons (same distance), the cost doubles to $1,200.

The Volume-to-Weight Trap (Lighter ≠ Always Cheaper)

Steel is dense, so shipments usually hit the truck's weight limit before filling its volume. However, lightweight alternatives like GFRP rebar are bulkier. You may run out of trailer space before reaching the weight limit, forcing you to use more trucks for the same number of bars—increasing cost per kg.

Rule of thumb: For standard steel, minimize cost by shipping full truckloads (22–25 tons per semi-trailer). For lightweight rebar, calculate cost per piece or per meter of coverage, not just per kg.

Full Truckloads vs. Partial Loads

• Full truckload (FTL): Lowest cost per ton. You pay a flat rate for the truck, typically $2–$4 per mile for 20–25 tons.
• Less-than-truckload (LTL): Higher per-ton cost because you share space and pay for handling.

Whenever possible, consolidate orders or coordinate delivery schedules to hit full truckload quantities.

Fuel Surcharges and Distance Fluctuations

Fuel prices change weekly. Many carriers add a fuel surcharge (often 10–30% of the base rate). For long-distance road construction projects, fuel can account for 30–40% of total transport cost. Always ask if the quoted rate includes fuel, and consider adding a contingency buffer (5–10%) for price swings.

Quick Cost Estimation Table (Steel Rebar, Truck Transport)

Shipment Weight (tons)	Distance (km)	Approx. Rate ($/ton/km)	Estimated Transport Cost
10	100	0.30	$300
20	100	0.28 (FTL discount)	$560
10	300	0.30	$900
22 (full load)	200	0.25 (bulk rate)	$1,100

Rates vary by region, fuel price, and season. Always get a current quote.

Structural Efficiency: Lighter Isn't Always Weaker

Sometimes, a lighter high-strength bar (e.g., Grade 75 or GFRP) replaces a heavier standard bar, reducing overall tonnage while maintaining strength. This lowers material cost, transport, and labor simultaneously. Always ask: Can a smaller or higher-grade bar do the same job?

Practical Tips for Construction Projects

• Use a rebar weight calculator before requesting shipping quotes. Even a 5% weight error can cost hundreds of dollars on a multi-truck job.
• Ask the supplier about local delivery minimums—some have fixed fees for short hauls that make partial loads uneconomical.
• Combine rebar with other steel deliveries (mesh, tie wire, formwork) to maximize truck utilization.
• Plan for unloading: Heavy rebar may require a crane or boom truck at the job site. Factor that rental into your logistics budget.

In short: rebar weight drives material, labor, and transport costs directly, but volume, fuel, and load consolidation also play major roles. Calculate first, then choose the most efficient bar size and shipping method—your project's bottom line will thank you.

Rebar Grades: What the Numbers Actually Mean

Rebar grades indicate yield strength — the point at which the steel starts to permanently deform under load. Higher grade means higher yield strength, which means the bar holds its shape under more stress before it gives.

In the US, yield strength is measured in ksi (kilopounds per square inch). Grade 60 means 60,000 psi of yield strength. That's the standard for most construction projects — residential, commercial, or light industrial. If a set of plans doesn't specify the grade, there's a strong chance they mean Grade 60.

US Rebar Grade Comparison

International Grade Equivalents

Wait — I almost skipped something important here. The difference between tensile strength and yield strength. They're not the same thing. Tensile strength is the maximum stress the steel can take before it actually breaks. Yield strength is the stress at which it starts to permanently bend. For design purposes, yield strength is what engineers work with. The bar yields before it breaks, which at least gives you a warning.

And for earthquake-prone areas: look for HRB400E or HRB500E in Chinese standards, or ASTM A706 in the US. These have tighter controls on the ratio of tensile to yield strength, which makes them better at absorbing seismic energy without snapping suddenly. That "E" suffix matters more than people realize.

Rebar Types: Carbon Steel, Epoxy, Stainless & GFRP

Size and grade tell you about strength. Bar type tells you about survivability — how the steel holds up against the specific conditions it'll face for the next 50 years.

Most of the time, standard carbon steel bars get the job done. They're strong, widely available, and priced right. But in certain environments — coastal areas, parking structures where road salt drips, structures near chemical plants — the right bar type makes the difference between a 30-year structure and a 70-year one.

Rebar Types at a Glance

Epoxy-coated bars — those green ones you see on bridge decks — get a lot of use in climates where roads get salted every winter. The coating protects the steel from chloride intrusion. Worth noting: epoxy-coated bars can be slightly heavier than plain ones due to the coating thickness, though the difference is minimal in most calculations.

Stainless steel rebar runs expensive. We're talking $4.50 to $9.00 per foot versus roughly $0.30 to $0.80 for standard carbon steel. But in an oceanfront structure or a chemical plant, the corrosion resistance extends the structure's life by decades. The upfront premium can absolutely be the cheaper choice long-term.

GFRP rebar is four times lighter than steel. I mentioned this almost as a side note earlier but it deserves a second here: that weight difference isn't just a convenience. It changes your transportation costs, your labor costs, and how many rods fit in a truckload. A lighter bar doesn't always mean a cheaper delivery, though — if the rods are bulkier by volume, you might fill the truck before you hit the weight limit. Always check both weight and volume when you're pricing a shipment.

ASTM, BS, and CSA Standards Explained

Standards exist so that when an engineer spec's "Grade 60 deformed bar per ASTM A615," everyone involved — from the mill to the inspector — knows exactly what they're getting. Without standards, every bar would require individual testing, and construction would grind to a halt.

In the US, the main governing body is ASTM International. Most structural rebar falls under one of these:

The difference between A615 and A706 trips people up. Both can be Grade 60. The key distinction is carbon equivalent — A706 limits it to 0.55% maximum, while A615 can run above 0.75%. Higher carbon content makes welding more difficult. If your specs say "weldable rebar" or the project is in a seismic zone, A706 is what you want. If you don't weld and you're not in an earthquake zone, A615 at a lower cost makes sense.

In the UK, BS 4449 governs rebar production. Canada uses CSA G30.18. Both set specific tolerances for diameter, rib geometry, and mechanical properties. If you're importing steel or working with international suppliers, confirming which standard applies to the bars you receive is not optional — it's the first thing a smart inspector will ask.

How to Pick the Right Rebar for Your Project

Last Tuesday, I was talking to a contractor friend who was arguing with his structural engineer about using #4 bars where the drawings called for #5. He thought it looked close enough. It wasn't. The area difference between those two bars is 71mm² — that's nothing when you're talking about the tensile capacity of a foundation wall.

Here's how I think through bar selection, in plain steps:

Step 1 — Read the structural drawings. The engineer already did the math. If they say #5 at 12 inches on center, don't substitute #4 at 12 inches. If you need to change anything, talk to the engineer of record. That's what they're there for.

Step 2 — Check local building codes. ACI 318 in the US sets minimum requirements for reinforcement in concrete structures. Local codes may add to those. Residential slabs often have minimum rebar requirements, even if your load calculations suggest you could get away with less.

Step 3 — Consider the environment. Will the structure be exposed to saltwater spray, de-icing chemicals, or high humidity for its lifetime? If yes, standard carbon steel without protection isn't your best call. Price out epoxy-coated or galvanized bars and compare lifecycle costs, not just purchase price.

Step 4 — Match bar size to structural role. As a rough guide:

Step 5 — Think about weight and logistics before you order. A large residential foundation might need several tons of rebar. At that scale, the difference between 12mm and 16mm bars affects not just structural performance but also how many trucks you need, how your crew handles the bars, and what equipment is on site. I've seen foremen realize mid-pour that the 20mm bars they ordered were too heavy to position manually in the wall forms. Plan ahead.

How to Read Rebar Markings in the Field

Every deformed rebar has a series of raised markings rolled into the surface during manufacturing. These aren't decorations. They tell you exactly what you're holding, if you know how to read them.

Reading from the top of the bar down:

First marking: One or two letters that identify the producing mill. Each mill has its own assigned code.

Second marking: The bar size number. A #5 bar has the numeral 5 (or 16 in metric) rolled into its surface. This is the most useful marking on the bar.

Third marking: A letter indicating the steel type. S = carbon steel (A615), W = low-alloy steel (A706), SS = stainless steel (A955), CS = low-carbon chromium (A1035), A = axle steel (A996).

Fourth marking: Grade indication. For Grade 60, you'll see a single continuous line. Grade 75 gets two lines. Grades 80 and 100 have three lines. Grade 120 uses four. Alternatively, the grade number itself may be stamped directly on the bar.

If you're on a job where mixed bars from different suppliers got shuffled together — which happens more than it should — reading the markings is the only reliable way to sort them. Don't eyeball it. Two bars that look similar in diameter can be different grades and types. The markings are there for exactly this situation.

How to Physically Measure Rebar in the Field

Markings tell you what a bar is supposed to be. But sometimes markings are worn, missing, or you're looking at old stock that came from who-knows-where. Here's how to measure rebar yourself with basic tools — no guesswork required.

Measuring Diameter with a Caliper (Most Accurate)

Digital or dial calipers work best for bars up to about 25mm (a #8).

Steps:

1. Clean off any rust or debris so you're measuring steel, not dirt.
2. Open the caliper jaws and place them perpendicular to the bar's length.
3. Close the jaws until they just touch both sides of the bar — don't squeeze.
4. Read the measurement. Then check it against the chart below.

Important: Rebar has raised deformations (ribs). You want the nominal diameter — measure the smooth cross-section between the ribs, not across the tops of them.

Measuring Diameter with a Tape Measure (No Caliper)

No caliper on hand? Wrap a flexible tape measure around the bar to get the circumference, then do one quick bit of math.

Formula: Diameter = Circumference ÷ π (3.1416)

Steps:

1. Wrap a tape measure around the bar, keeping it perpendicular to the length.
2. Record the circumference in inches or millimeters.
3. Divide by 3.1416.

Example: Circumference = 1.57 inches → 1.57 ÷ 3.1416 = 0.5 inches → that's a #4 bar.

This method is less precise than a caliper, but it's plenty accurate for larger bars (#6 and up). I've used it more times than I'd like to admit on jobs where my caliper was back in the truck.

Nominal vs. Actual Diameter: What's the Difference?

Rebar sizes are nominal — standardized labels, not exact measurements. A #4 bar isn't always exactly 0.500 inches. Manufacturing tolerances (per ASTM) allow small variations.

US Size	Nominal Diameter (in)	Typical Actual Range (in)
#4	0.500	0.498–0.502
#5	0.625	0.622–0.628
#6	0.750	0.746–0.754

If your measurement falls way outside the typical range — say a #4 reads 0.480 or 0.520 — question the bar. Don't just assume the marking is right.

How to Measure Total Length

This sounds obvious, but I've seen it done wrong more than once:

• Measure from end to end along the bar's centerline, not along the outside curve if the bar is bent.
• For straight stock bars, standard lengths are 20 ft, 40 ft, or 12 meters. Still, always run the tape. I've personally unloaded a bundle of "20-foot" bars that ran 19 feet 6 inches. That adds up fast when you need 50 of them.

Quick Field Reference: Diameter by Size

US Size	Nominal Diameter (in)	Nominal Diameter (mm)	Circumference (in)
#3	0.375	9.5	1.18
#4	0.500	12.7	1.57
#5	0.625	15.9	1.96
#6	0.750	19.1	2.36
#7	0.875	22.2	2.75
#8	1.000	25.4	3.14

Keep a small caliper in your truck or a tape measure in your pocket. Ten seconds of measuring can save you from placing the wrong bar — a mistake I've made exactly once. Learned that lesson.

You may also want to read related topics:

• Rebar Codes & Standards: What I Learned Building My First Project
• Rebar Takeoff: Formula, Steps, Waste Reduction & Real Examples
• How to Create a Rebar Cutting and Bending Schedule (BBS) for Your Construction Project
• Rebar Lap Splice Length: How It Affects Weight
• Rebar Density, Unit Weight, and Material Properties: Essential Technical Insights
• Rebar Sizes, Diameters, Grades, Weights, Cost & Transportation (with Complete Charts)

These help you see the bigger picture.

FAQ: Rebar Size, Diameter, and Weight

Data sourced from ASTM A615, ASTM A706, CSA G30.18, and BS 4449 specifications. Always verify against current local codes and project-specific engineering requirements.