How do you calculate rebar weight per foot?

Rebar weight per foot is calculated from the bar diameter using the formula w = 0.167 × d², where w is in pounds per foot and d is the bar diameter in inches. For example, a #5 bar has a diameter of 0.625 in, so w ≈ 0.167 × 0.625² ≈ 0.065 lb/in × 12 in/ft ≈ 1.043 lb/ft. In practice, standard tables list #5 rebar as about 1.043 lb/ft.

What density of steel does this rebar calculator use?

This calculator uses a typical density of carbon reinforcing steel of 7850 kg/m³ (approximately 490 lb/ft³). This is standard for most structural design and quantity takeoff calculations.

Can I mix imperial and metric units when calculating rebar weight?

You can choose either imperial or metric mode in the calculator. In imperial mode, bar sizes are #3, #4, etc. with lengths in feet or inches. In metric mode, bar diameters are in millimeters with lengths in meters. The tool converts everything internally and reports weight in both kilograms and pounds.

How accurate is the rebar weight from this calculator?

The calculator assumes nominal bar diameters and a standard steel density. Actual delivered weight can vary slightly due to manufacturing tolerances and mill certificates, but for estimating quantities, transport loads, and concrete reinforcement takeoffs, this level of accuracy is generally sufficient.

Why do rebar weight tables sometimes show slightly different values?

Different tables may round bar diameters, use slightly different steel densities, or round the final weight per foot or per meter. Codes and standards also define nominal dimensions that may differ from measured values. These differences are usually small and do not affect typical design or estimating decisions.

Rebar Weight Calculator – Bar Size, Length, Pieces & Total Steel Weight

How this rebar weight calculator works

This tool computes rebar weight from the bar diameter, length, quantity, and steel density. It supports:

US bar sizes (#3, #4, #5, #6, #7, #8, #9, #10, #11, #14, #18)
Metric diameters (8–40 mm and more)
Custom diameters if your bar size is not listed

Rebar weight formula

The weight of a steel bar is based on its volume and the density of steel:

In SI units

Diameter in meters: \( d \) (m)

Length: \( L \) (m)

Steel density: \( \rho \approx 7850 \,\text{kg/m}^3 \)

Cross-sectional area: \( A = \pi \frac{d^2}{4} \)

Weight of one bar:

\[ W_\text{bar} = A \cdot L \cdot \rho \]

From this, we get the common unit weights:

Weight per meter: \( w_\text{m} = A \cdot \rho \) (kg/m)
Weight per foot: \( w_\text{ft} = w_\text{m} \times 0.3048 \) (kg/ft)

Imperial shortcut formula

In US practice, rebar weight per foot is often approximated directly from the diameter in inches:

Let \( d \) be the bar diameter in inches. Then:

\[ w_\text{ft} \approx 0.167 \, d^2 \quad (\text{lb/ft}) \]

For example, #5 rebar has \( d = 0.625 \,\text{in} \):

\[ w_\text{ft} \approx 0.167 \times 0.625^2 \approx 1.04 \,\text{lb/ft} \]

Step-by-step example

Suppose you need the total weight of 25 pieces of #5 rebar, 20 ft long each.

#5 bar diameter = 0.625 in (≈ 15.9 mm).
Weight per foot from table ≈ 1.043 lb/ft.
Weight per bar = 1.043 × 20 = 20.86 lb.
Total weight = 20.86 × 25 ≈ 521.5 lb (≈ 236.6 kg).

If you enter these values in the calculator, it will show essentially the same result using the exact geometric formula.

Typical uses of a rebar weight calculator

Estimating material orders – convert bar schedules into total tons or kilograms of steel.
Transport and lifting planning – check truck load limits or crane lift capacities.
Cost estimation – many suppliers quote prices per ton; you need total weight to estimate cost.
Concrete reinforcement takeoff – quickly summarize bar lists from drawings.

Assumptions and limitations

Uses nominal bar diameters from common US and metric standards.
Assumes straight bars; bends and hooks add a small amount of extra length and weight.
Density is assumed constant; you can override it if you have mill certificate data.

FAQ

Can I change the steel density?

Yes. If you are working with stainless steel or a specific alloy, enter its density in kg/m³. The calculator will recompute all weights using your value.

What if my bar size is not in the list?

Select “Custom diameter” under Bar standard and type the diameter directly (in inches or millimeters, depending on the current mode). The calculator will treat it like any other bar.

Are the results suitable for structural design?

The calculator is intended for quantity takeoff and logistics, not for checking structural capacity. For design, always follow the relevant building codes and use appropriate design software or spreadsheets.

Rebar Weight Calculator