Use this steel bar weight calculator to estimate the weight of solid round, square, or flat stock before you buy or cut it. Enter the bar dimensions, length, and number of pieces. You can work in inches and feet or millimeters and meters. If you know the price per pound or kilogram, the tool can estimate the material cost too.
Workshop tool
Calculate your bar weight
Enter the size of a solid steel bar to estimate its weight. Choose round, square, or flat stock. The calculator uses an approximate mild steel density of 7.85 g/cm³.
Estimated weight
- One bar
- All bars
- Weight per foot
- Estimated material cost
These are theoretical weights for solid mild steel. Check the supplier’s listed weight when you need an exact figure.
How to use the calculator
Pick the shape of your stock and enter its cross-section. For round bar, measure the diameter. For square bar, enter the width of one side. For flat bar, enter both width and thickness. Then enter the length of each bar and the number of identical bars. Imperial dimensions use decimal inches, so 3/8 inch is 0.375 inch.
The result shows one bar, the full batch, and the weight per foot or meter. The optional cost field uses the total weight and the price you enter. It does not include cutting loss, shipping, tax, or supplier minimums.
How steel bar weight is calculated
Weight is the cross-sectional area multiplied by length and density. This tool uses an approximate mild steel density of 7.85 g/cm³, or 7,850 kg/m³. A round bar has an area of π × (diameter ÷ 2)². A square bar has an area of side × side. A flat bar has an area of width × thickness. The calculator converts the dimensions to millimeters, works out the volume, and converts the result to pounds and kilograms.
For example, an 8-inch length of 3/8-inch square mild steel bar comes to about 0.319 lb (0.145 kg). That is a useful starting size for the beginner decorative hook project. Your finished hook will weigh less after cutting, grinding, and scale loss.
Why the actual weight may differ
This is a theoretical weight for a solid bar with the dimensions you enter. Steel grades vary in density, and real stock may have dimensional tolerances, rounded corners, scale, or coatings. A supplier’s listed weight or a scale is the better figure when you need a precise shipping or inventory number. For a price estimate, use the supplier’s actual price per pound or kilogram.
Density reference: Online Metals weight calculator. The calculator runs in your browser; the dimensions and price you enter are not sent to ForgingWorld.