Quick answer
Rebar weight = nominal weight per foot × length × number of bars. Ten #4 bars 20 ft long weigh 0.668 × 20 × 10 = 133.6 lb (60.6 kg).
Enter the bar size, length and number of bars. The calculator returns total weight in pounds and kilograms.
Related tools: Pipe Weight Calculator: Weight of a hollow round pipe from its outside diameter, wall thickness and length. Glass Weight Calculator: Weight of a glass pane from its dimensions. Gold Weight Calculator: Mass of pure gold from its volume.
How to use the Rebar Weight Calculator
- Choose bar size: #3, #4, #5, #6, #7 and #8 and 5 more.
- Enter length of each bar (ft) (above 0).
- Enter number of bars (a whole number, 1 or more).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Bar size | Choose one: #3; #4; #5; #6; #7; #8; #9; #10; … | Starts at #4 |
| Length of each bar | A number, in ft | > 0 |
| Number of bars | A whole number | ≥ 1 |
Formula and method
Formula
weight = nominal weight per foot × length × number of bars
IEEE-754 double precision; shown to the decimals indicated.
Nominal weights per foot for US bar sizes #3–#18 (ASTM A615): 0.376, 0.668, 1.043, 1.502, 2.044, 2.670, 3.400, 4.303, 5.313, 7.650, 13.600 lb/ft. Plan geometry only; confirm quantities with your supplier and local code before ordering.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Bar size = #4; Length of each bar = 20; Number of bars = 10.
| Result | Value |
|---|---|
| Total weight | 133.6 lb |
| In kilograms | 60.6 |
Example 2
Inputs: Bar size = #5; Length of each bar = 12; Number of bars = 25.
| Result | Value |
|---|---|
| Total weight | 312.9 lb |
| In kilograms | 141.9 |
Example 3
Inputs: Bar size = #8; Length of each bar = 40; Number of bars = 3.
| Result | Value |
|---|---|
| Total weight | 320.4 lb |
| In kilograms | 145.3 |
The first line is the headline result (total weight). Below it the rebar Weight Calculator lists in kilograms, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Weights per foot
Common nominal weights: #3 0.376 lb/ft, #4 0.668, #5 1.043, #6 1.502. Weight grows with the square of the diameter. Rebar is often priced by the pound or ton.
Nominal values
Actual bars vary slightly from nominal weights within ASTM tolerances. Add a little for hooks, bends and laps.
How the result changes with length of each bar
Holding every other input at the first worked example, this table changes only length of each bar. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Length of each bar | Total weight | In kilograms |
|---|---|---|
| 10 | 66.8 lb | 30.3 |
| 20 | 133.6 lb | 60.6 |
| 40 | 267.2 lb | 121.2 |
| 80 | 534.4 lb | 242.4 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Length of each bar: entering "0" shows "Length of each bar must be greater than 0." beside that field and no result.
- Number of bars: entering "0" shows "Number of bars must be at least 1." beside that field and no result.
Choosing between the Rebar Weight Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Pipe Weight Calculator](/construction/pipe-weight/) | outside diameter, wall thickness and length | Pipe weight |
| [Glass Weight Calculator](/construction/glass-weight/) | length, width and thickness | Glass weight |
| [Gold Weight Calculator](/construction/gold-weight/) | volume and unit | Mass |
| [Metal Weight Calculator](/construction/metal-weight-calculator/) | material, shape and dimension A | Weight |
| [Money Weight Calculator](/construction/money-weight/) | denomination and amount | Weight |
Background: construction estimates
Material quantities are geometry plus a margin. Calculate the exact volume or area, add an allowance for waste, spillage, cuts and uneven ground (calculator pages commonly mention 5 to 10 percent, a rule of thumb that varies by material and job) and round up to whole units. One cubic yard is exactly 27 cubic feet.
Suppliers often have minimum order sizes and may charge for small loads, so confirm quantities, product yields and local code with your supplier or a qualified estimator before ordering.
Assumptions and limitations
- Nominal weights; actual bars vary slightly
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for length of each bar and number of bars to confirm this.
Frequently asked questions
How much does a 20 ft #4 bar weigh?
A 20 ft length of #4 bar weighs about 13.4 lb.
What is the diameter of #5 rebar?
#5 rebar is 5/8 inch (0.625 in) in nominal diameter.
Does grade affect weight?
No. Nominal weight depends on bar size, not on steel grade.
What does the Rebar Weight Calculator calculate?
Weight of reinforcing bar by size and length. It returns Total weight and In kilograms.
What formula does the Rebar Weight Calculator use?
weight = nominal weight per foot × length × number of bars. Nominal weights per foot for US bar sizes #3–#18 (ASTM A615): 0.376, 0.668, 1.043, 1.502, 2.044, 2.670, 3.400, 4.303, 5.313, 7.650, 13.600 lb/ft.
What do I need to enter in the rebar Weight Calculator?
You enter Bar size, Length of each bar (ft) and Number of bars.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Nominal weights; actual bars vary slightly.
What is an example of a rebar Weight result?
With bar size #4, length of each bar 20 and number of bars 10, the total weight is 133.6 lb.
Where does the method come from?
The method follows: ASTM A615/A615M, Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement (nominal weights).
Can I rely on this calculator for a decision?
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work. For this calculator in particular: Nominal weights; actual bars vary slightly.
Related calculators
- Pipe Weight Calculator — Weight of a hollow round pipe from its outside diameter, wall thickness and length.
- Glass Weight Calculator — Weight of a glass pane from its dimensions.
- Gold Weight Calculator — Mass of pure gold from its volume.
- Metal Weight Calculator — Weight of a plate, round bar or square bar in common metals.
- Money Weight Calculator — Weight of an amount of US bills or coins.
- Steel Plate Weight Calculator — Weight of a carbon steel plate from its dimensions.
Sources
- ASTM A615/A615M, Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement (nominal weights)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.