Updated 29 August 2026 Unit weight tells you the load created by one unit volume; density tells you the mass in that volume. For preliminary Indian dead-load work, commonly used design values include reinforced concrete at 25 kN/m³ , plain concrete at 24 kN/m³ , brick masonry at 19.2 kN/m³ and steel at 78.5 kN/m³ . The project engineer must still select the value appropriate to the actual material, assembly and governing documents. Do not use every number on a “density chart” in the same way. A design unit weight from a loading standard, a manufacturer-declared product density and a loose material's measured bulk density are different evidence. RCC design reference Steel design reference Measured density Quick unit-weight chart for common building materials The table below is a compact working reference. The first five rows are design values used for dead-load calculations. Product and site materials are deliberately separated because their values can vary with composition, declared grade, moisture and packing. The official IS 875 Part 1 preview describes its scope as unit weight or mass for building materials, components and stored materials used to determine dead loads. Before relying on an edition or amendment, use BIS's Know Your Standard service and the project's approved standards register. These selected design references are not a product catalogue. Variable or proprietary materials need project-specific evidence. Calculate material weight, dead load or measured density The worksheet has four modes: Slab / layer: area × thickness × unit weight. Wall: length × height × thickness × unit weight. Known volume: volume × density or unit weight. Measured density: entered mass ÷ entered volume, compared with a selected project reference. Material Weight, Dead Load & Density Record Forward-calculate load from geometry or reverse-check measured mass and volume Choose a reference material, or select Custom material to enter your own density and unit weight. Choose measurement units before entering values. Switching units does not convert the entered numbers. Use the actual drawing or measured build-up. These values stay included in your result when this section is closed. Complete the record details before using an inspection or approval record. Primary material load 116.13 kN over 4.645 m³ · IS 875 design value Distributed load Unfactored dead load Choose a second material above Preliminary unfactored dead-load estimate only. The built-in options are fixed references; use Custom material for an approved product, assembly or measured value. A structural engineer must confirm finishes, openings, reinforcement, supports, load combinations and local code requirements. The measured-density mode is a screening record. A result near a reference value does not identify a material, prove compressive strength, establish moisture condition or decide acceptance. Use the applicable sampling and test method plus the project specification for those decisions. The four quantities people commonly mix up For a physical conversion, unit weight ≈ density × 9.81 / 1,000 . Therefore 2,500 kg/m³ is about 24.525 kN/m³. A design reference may use a rounded 25 kN/m³, so the calculator stores mass density and design unit weight separately rather than silently forcing one from the other. Worked calculations RCC slab self-weight A 400 sq ft slab is 37.161 m². At 125 mm thickness: volume = 37.161 × 0.125 = 4.645 m³ ; mass at 2,500 kg/m³ = 11,612.88 kg , or 11.61 tonnes ; unfactored load at 25 kN/m³ = 116.13 kN ; distributed slab self-weight = 25 × 0.125 = 3.125 kN/m² . That is slab self-weight only. Finishes, ceilings, partitions, services, equipment, imposed load and load combinations remain separate design inputs. Brick-masonry wall line load For a wall 4 m long, 3 m high and 230 mm thick: volume = 4 × 3 × 0.23 = 2.76 m³ ; total mass at 1,920 kg/m³ = 5,299.2 kg ; total unfactored load at 19.2 kN/m³ = 52.992 kN ; line load = 52.992 ÷ 4 = 13.248 kN/m . Openings, lintels, finishes and the actual masonry system must be handled explicitly. Do not replace an approved wall load with a midpoint from an internet range. Reverse-check a measured bulk density Suppose a levelled loose-material volume is 2.5 m³ and its net measured mass is 4,100 kg: Observed bulk density = 4,100 ÷ 2.5 = 1,640 kg/m³. Record the weighing basis, container tare, moisture condition, measurement method and time. The arithmetic alone does not convert that observation into a dry density or an acceptance verdict. How to choose the right value 1 Name the exact material or assembly A single brick, masonry wall, loose sand and compacted fill are not interchangeable. Name the exact material or assembly A single brick, masonry wall, loose sand and compacted fill are not interchangeable.

2 State the purpose Structural dead load, procurement conversion and field screening need different evidence. State the purpose Structural dead load, procurement conversion and field screening need different evidence. 3 Find the governing source Use the adopted loading standard, issued calculation basis, product declaration or specified test method. Find the governing source Use the adopted loading standard, issued calculation basis, product declaration or specified test method. 4 Match the condition Record moisture, packing, voids, reinforcement, finishes and whether the value represents a component or full assembly. Match the condition Record moisture, packing, voids, reinforcement, finishes and whether the value represents a component or full assembly. 5 Save the calculation record Keep dimensions, source, revision, assumptions, result and reviewer together. Save the calculation record Keep dimensions, source, revision, assumptions, result and reviewer together. A precise calculation with the wrong material condition is still the wrong calculation. Design value, declared value and measured value Design value. A value selected by the engineer for structural calculations under the adopted loading standard and project basis. It may be intentionally rounded and must be used consistently. Declared product value. A manufacturer or supplier value for an exact product and stated condition. Check the document revision, product grade and test basis before transferring it to a load model. Measured value. A result from an identified specimen, delivery or field volume. It applies to the recorded sample and condition. It does not automatically replace the design value. Benchmark range. A screening aid used to spot questions. It is not an acceptance limit unless the project specification explicitly makes it one. Common unit-weight mistakes Using a single brick's density for a finished masonry wall without mortar or finish allowances. Treating loose bulk density as solid-particle density. Converting tonnes to kN as though they were the same physical quantity. Adding imposed load to dead load without preserving the load categories. Using a range midpoint as a conservative design value. Comparing wet delivered mass with a dry-density reference. Measuring a stockpile's outside dimensions without accounting for its actual geometry. Claiming strength, quality or compliance from density alone. Frequently asked questions What is the unit weight of RCC? For preliminary dead-load calculations, 25 kN/m³ is a commonly used Indian design reference for reinforced concrete. Use the value adopted in the project's structural calculation basis. What is the unit weight of PCC? 24 kN/m³ is a commonly used design reference for plain cement concrete. Confirm the actual material and approved project value. What is the unit weight of brick masonry? 19.2 kN/m³ is a common reference for burnt-clay brick masonry with mortar. It is an assembly value, not the density of one dry brick. How do I convert kg/m³ to kN/m³? For a physical conversion, multiply by 9.81 and divide by 1,000. Keep an adopted rounded design value separate when the project uses one. Is density enough to accept concrete or masonry? No. Density does not establish compressive strength, durability, workmanship or compliance. Follow the specified sampling, testing and acceptance clauses. Can I use the heaviest end of every online range for design? Not as a substitute for engineering judgment. The source, material condition and complete assembly must match the project. Have the structural engineer approve the adopted value. Does one brass have a fixed weight? No. One brass is exactly 100 cubic feet of volume; its mass depends on the material's measured or adopted bulk density. See the brass converter . Why are mass density and design unit weight separate in the calculator? Because physical conversion may produce a non-rounded number while a loading standard or approved calculation basis uses a rounded design reference. Showing both prevents a hidden mismatch. Related calculators and references Concrete Density Checker kN to Ton-Force Record Steel Bar Unit Weight Brick Delivery Checker Sand Order Calculator All CivilSite standards references Found this useful? Send it to someone building right now The arrow button opens your phone's own share sheet — use it for Instagram, Messages or any other app you have installed. CivilSite Editorial Team ✓ Engineer reviewed Written and reviewed by practising civil engineers with 10+ years of Indian residential construction experience.