Rebar Weight Calculator
This rebar weight calculator finds the weight of reinforcing steel from the bar diameter, the length, and the number of bars. Enter them and the rebar weight calculator returns the weight per meter and the total weight in kilograms. As a steel rebar calculator it uses the standard steel density, so the result matches mill tables for every common bar size.
Results
The Rebar Weight Calculator is part of our Weight collection. Browse more weight to size, convert, and check your work alongside this tool.
What the steel rebar calculator shows
The steel rebar calculator turns a bar size and length into a weight. It finds the cross section from the diameter, multiplies by the length and the steel density, and gives the weight per meter and the total. Because it works from geometry and density, this steel rebar calculator matches a steel rebar weight calculator or a weight of rebar calculator to the gram for any bar size.
The formula for rebar weight
The formula for rebar weight comes from the round cross section and the density of steel, which simplifies to a well known shortcut:
d is the bar diameter in millimeters, and 162 folds in the steel density of about 7,850 kg per cubic meter. Multiply the weight per meter by the length and the number of bars for the total. This rebar weight calculation formula is why a 12 mm bar always works out near 0.89 kg per meter.
Steel rebar weight calculator example
A 12 mm bar, 12 m long, one bar. The steel rebar weight calculator applies the formula:
So one 12 m length of 12 mm bar weighs about 10.65 kg. Change the size and the rebar weight calculator returns a new weight at once.
How to use the rebar weight calculator
Enter the bar diameter in millimeters, the bar length, and the number of bars, and the rebar weight calculator returns the weight per meter and the total weight. Use the nominal diameter stamped on the bar, since that is what mill tables and this reinforcement steel weight calculator both assume. For a full schedule, run each bar size once and add the totals.
Reading the rebar weight calculator result
The weight per meter is the unit weight for that bar size; the total is that value times length times quantity. Order steel by total weight, since mills and yards price by the kilogram or ton. For a whole job, run each bar size, add the totals, then add a small allowance for laps and offcuts. The rebar weight calculator gives the nominal weight; a deformed bar weight calculator lands on the same figure, because the ribs are counted in the nominal size.
When to use the steel rebar calculator
- Pricing an order by weight with the steel rebar calculator
- Checking a delivery against the weight of rebar calculator
- Building a bar bending schedule size by size
- Converting a length of bar to a reinforcement bar weight per meter
Common rebar weight calculator mistakes
- Using an odd diameter. Enter the nominal size stamped on the bar, which is what the formula for rebar weight assumes.
- Adjusting for grade. Mild and high yield steel weigh the same, so grade does not change the weight of rebar.
- Forgetting laps. Add a few percent for laps and offcuts after the reinforcement bar weight per meter total.
Tips for accurate takeoffs
- Run each bar size once and add the totals for a schedule.
- Order by weight, since steel is priced by the kilogram or ton.
- Add a small allowance for laps, hooks, and cut waste.
The weight of rebar formula and kg per meter
The weight of rebar formula is just the weight of a steel cylinder written for bar sizes. Take the round area, pi times the radius squared, multiply by length for the volume, and multiply by the steel density of about 7,850 kg per cubic meter for the mass. Fold the density and the unit changes together and it collapses to d² divided by 162, with d in millimeters and the answer in kg per meter. This is why the rebar weight kg per meter formula needs only the diameter: a 16 mm bar is 1.58 kg per meter, a 20 mm bar is 2.47, and each step up in size raises the weight by the square of the diameter. Grade does not change it, since mild and high yield steel share the same density.
Steel rebar weight per meter by bar size
Steel rebar weight per meter climbs fast because it follows the diameter squared, not the diameter. Doubling the bar size from 10 mm to 20 mm nearly quadruples the unit weight, from 0.62 to 2.47 kg per meter, which is why a schedule dominated by large bars gets heavy quickly. Plan orders by weight rather than length, add a few percent for laps and cut waste, and confirm the total against a delivery note. When you also need the count and spacing rather than the mass, the rebar calculator lays out the bars, and this tool turns that layout into a weight to buy.
Steel rebar weight per meter chart
Nominal steel rebar weight per meter for common bar sizes, from the d² ÷ 162 formula this rebar weight calculator uses:
| Bar diameter | Weight per meter | Weight per 12 m |
|---|---|---|
| 8 mm | 0.395 kg/m | 4.74 kg |
| 10 mm | 0.617 kg/m | 7.40 kg |
| 12 mm | 0.888 kg/m | 10.65 kg |
| 16 mm | 1.580 kg/m | 18.96 kg |
| 20 mm | 2.469 kg/m | 29.63 kg |
| 25 mm | 3.858 kg/m | 46.30 kg |
Rebar Weight Calculator FAQ
What is the formula for rebar weight?
The formula for rebar weight is weight per meter equals d² divided by 162, with d the diameter in millimeters. Multiply by length and quantity for the total, which is what the rebar weight calculator does.
What does a 12 mm bar weigh per meter?
About 0.888 kg per meter, from 12² divided by 162. That steel rebar weight per meter is the nominal value mill tables list.
Where does the number 162 come from?
It folds the steel density of 7,850 kg per cubic meter into the round cross section. The rebar weight calculation formula d² divided by 162 is the tidy result.
Does it work for deformed bars?
Yes. A deformed bar weight calculator uses the nominal diameter, since the ribs are already counted in that size, so the weight matches plain round steel of the same nominal bar.