Rebar Weight Calculator
Calculate the weight of steel rebar for construction projects. Enter the bar diameter and total length to instantly find the weight in pounds — useful for ordering materials and estimating shipping costs.
About this calculator
Rebar weight is calculated using the steel density formula derived from the bar's cross-sectional area. The standard formula is: Weight (lb) = (diameter² × length × 0.006162) / 162. Here, diameter is in millimeters (or the bar designation number), length is in feet, and 0.006162 is a constant derived from steel's density (490 lb/ft³) combined with unit conversions. The division by 162 normalizes the result to pounds per foot based on standard rebar sizing conventions. This formula is widely used in civil and structural engineering to estimate rebar quantities for slabs, beams, columns, and footings before procurement. Accurate weight estimates help contractors control costs and ensure structural specifications are met.
How to use
Suppose you need rebar with a diameter of 16 and a total length of 100 feet. Step 1: Square the diameter — 16 × 16 = 256. Step 2: Multiply by the length — 256 × 100 = 25,600. Step 3: Multiply by 0.006162 — 25,600 × 0.006162 = 157.75. Step 4: Divide by 162 — 157.75 / 162 ≈ 0.974 lb. For larger projects with 500 feet of the same bar, the weight scales to approximately 4.87 lb, helping you plan material orders accurately.
Frequently asked questions
How do I calculate the weight of rebar per foot?
Rebar weight per foot depends on the bar's diameter. Using the formula Weight = (diameter² × length × 0.006162) / 162, you can set length to 1 foot to find the per-foot weight. For example, a #5 rebar (diameter 15.875 mm) weighs approximately 0.668 lb/ft. This per-foot value is useful for quickly scaling up to any total length needed on a job site.
What unit should the rebar diameter be entered in for this calculator?
The diameter field uses the bar's numeric designation or millimeter measurement depending on the implementation. Standard US rebar sizes range from #3 (9.5 mm) to #18 (57.3 mm). Always confirm which unit system the calculator expects before entering your value to ensure the output weight in pounds is accurate. If your plans specify imperial bar numbers, verify the corresponding metric diameter before calculating.
Why is an accurate rebar weight estimate important for construction projects?
Knowing the exact weight of rebar is critical for budgeting material costs, planning logistics, and ensuring structural integrity. Steel is sold by weight, so underestimating leads to costly reorders and project delays. Overestimating wastes money and increases dead load on structures. Accurate weight calculations also inform crane and transport capacity requirements when moving large quantities of steel on-site.