Steel Weight
Calculate steel weight for round, square, hex bars, plates, pipes. Select shape and alloy, enter dimensions for instant kg/lb weight with volume and density info.
About This Calculator
Our Steel Weight Calculator helps engineers, fabricators, contractors, metalworkers, and DIY enthusiasts determine the exact weight of steel components in various shapes and sizes. Whether you need the weight of a round bar for a machined shaft, a rectangular plate for a fabrication project, a pipe for plumbing or structural use, or a hexagonal bar for custom fasteners, this calculator provides instant and accurate results in both kilograms and pounds.
The calculation uses the standard formula: weight = volume × density. The volume depends on the shape — for a round bar it is the cylinder volume (π × r² × length), for a rectangular plate it is length × width × thickness, for a pipe it is the annular cross-section area × length, and for hexagonal bars it uses the hexagonal area formula (3√3/2 × side²). Each steel alloy has a specific density — mild steel at 7,870 kg/m³, stainless steel at 8,030 kg/m³, carbon steel at 7,840 kg/m³, and tool steel at 7,715 kg/m³ — ensuring accurate results for your specific material. The calculator supports multiple unit systems (mm, cm, m, inches, feet) for global convenience and includes a quantity multiplier for multiple identical pieces.
How to Use
First, select the steel shape from the dropdown — choose from round bar, square bar, rectangular plate/bar, pipe/tube, or hexagonal bar. Next, select the steel alloy type to apply the correct density. Choose your preferred unit system (mm, cm, m, in, or ft), then enter the required dimensions for the selected shape. Enter the length and quantity of identical pieces, then click Calculate. The results show total weight in kilograms and pounds, volume in cubic meters, density used, weight per piece, and a detailed breakdown. Use the chart tabs to compare weight in kg vs lb or see how weight varies across different steel alloys.
Regional Notes
India: Steel is commonly measured in millimeters with mild steel (MS, Fe-410/250) and stainless steel (SS 304/316) being the most common grades. TMT bars are specified by diameter in mm (8 mm to 32 mm) and priced per kilogram or per metric ton. The formula d²/162 is widely used in Indian construction for quick TMT bar weight estimation.
US: Steel dimensions are typically in inches and feet. Round bars are specified by diameter in inches, plates by thickness in gauge or fractional inches. Weight is often quoted in pounds per foot for bars or pounds per square foot for plates. Common steel grades include A36 (carbon steel) and 304/316 stainless.
UK: Steel dimensions commonly use millimeters for thickness and meters for length, with weights referenced in kilograms. British standards (BS EN 10025 for structural steel, BS EN 10210 for hollow sections) govern steel specifications. Steel prices are typically quoted per metric ton.
Frequently Asked Questions
How do you calculate steel weight?
Steel weight is calculated by multiplying the volume of the steel piece by the density of the steel alloy. The formula is: weight = volume × density. For multiple pieces, multiply by the quantity. Our calculator supports round bars, square bars, rectangular plates, pipes, and hexagonal bars with steel type selection for accurate density values.
What is the density of steel in kg/m³?
The density of steel varies by alloy. Common values include: mild steel 7,870 kg/m³, stainless steel 8,030 kg/m³, carbon steel 7,840 kg/m³, cold-drawn steel 7,830 kg/m³, and tool steel 7,715 kg/m³. Our calculator uses the specific density for each selected alloy for accurate weight results.
How much does a 12 mm steel rod weigh per meter?
A 12 mm diameter mild steel round bar weighs approximately 0.888 kg per meter. This is calculated using the formula: weight = (π × d² ÷ 4) × length × density, where d = 0.012 m and density = 7,870 kg/m³. A standard 12 m rod would weigh about 10.66 kg.
What is the 162 formula for steel weight?
The formula W = d²/162 is an approximate formula used in construction for calculating the weight of TMT steel bars per meter, where d is the diameter in mm. It simplifies (π/4) × (10⁻³)² × 7850 ≈ 1/162. This gives weight in kg/m for cylindrical steel bars with a density of 7,850 kg/m³.
What is the difference between steel plate and steel bar?
Steel plate (or sheet) is a flat, rectangular piece of steel with width significantly greater than thickness, commonly used for structural fabrication, tanks, and flooring. Steel bar refers to long, straight pieces with uniform cross-section — round, square, or hexagonal — used for reinforcement, shafts, railings, and machining stock.
How do I calculate the weight of a steel pipe?
To calculate steel pipe weight, compute the cross-sectional area of the pipe wall (π/4 × (OD² - ID²), where ID = OD - 2 × wall thickness), multiply by the length to get volume, then multiply by the steel density. Our calculator handles pipe weight for any outer diameter and wall thickness automatically.
Why is steel weight important in construction?
Steel weight is critical for structural load calculations, foundation design, transportation logistics, lifting equipment selection, and material cost estimation. Engineers use accurate steel weights to ensure beams, columns, and supports are properly designed to safely carry the intended loads without overloading foundations.
Can I calculate weight for multiple steel pieces at once?
Yes, our calculator includes a Quantity input field. Enter the number of identical steel pieces to get the total combined weight. For example, 10 round bars of 2.71 kg each gives a total weight of 27.1 kg. The weight per piece is also shown in the results breakdown.