Free · No sign-up · Runs entirely in your browser
Calculate the mass of an object from its material and dimensions — steel, concrete, timber, water and more, as blocks, cylinders, pipes or spheres — then see its weight (force) on Earth.
Densities are typical values. Use supplier or engineering data where accuracy matters.
| Measure | Value |
|---|
Every mass calculation here comes from one relationship, applied after the geometry is worked out.
The formula is straightforward. What people actually get wrong is the volume — millimetres cubed into metres cubed is a factor of a billion, and dropping three zeros somewhere is the usual cause of an answer that is out by a thousand.
| Material | Density | 1 m³ weighs |
|---|---|---|
| Water (fresh) | 1,000 kg/m³ | 1.00 t |
| Water (sea) | 1,025 kg/m³ | 1.02 t |
| Steel | 7,850 kg/m³ | 7.85 t |
| Stainless steel | 8,000 kg/m³ | 8.00 t |
| Aluminium | 2,700 kg/m³ | 2.70 t |
| Copper | 8,960 kg/m³ | 8.96 t |
| Brass | 8,500 kg/m³ | 8.50 t |
| Lead | 11,340 kg/m³ | 11.34 t |
| Concrete | 2,400 kg/m³ | 2.40 t |
| Reinforced concrete | 2,500 kg/m³ | 2.50 t |
| Brick | 1,900 kg/m³ | 1.90 t |
| Sand (dry) | 1,600 kg/m³ | 1.60 t |
| Gravel | 1,680 kg/m³ | 1.68 t |
| Soil (dry) | 1,300 kg/m³ | 1.30 t |
| Pine (softwood) | 510 kg/m³ | 0.51 t |
| Hardwood (mixed) | 900 kg/m³ | 0.90 t |
| Plywood | 600 kg/m³ | 0.60 t |
| Glass | 2,500 kg/m³ | 2.50 t |
| PVC | 1,400 kg/m³ | 1.40 t |
| Ice | 917 kg/m³ | 0.92 t |
| Object | Volume | Mass |
|---|---|---|
| Steel plate 2400 × 1200 × 10 mm | 0.0288 m³ | 226.1 kg |
| Concrete slab 5 × 4 × 0.1 m | 2.0000 m³ | 4,800.0 kg |
| Plywood sheet 2400 × 1200 × 18 mm | 0.0518 m³ | 31.1 kg |
| Water in a 5000 L tank | 5.0000 m³ | 5,000.0 kg |
| Steel pipe 6 m, 100 mm OD, 5 mm wall | 0.0090 m³ | 70.3 kg |
Two of these are worth pausing on. A single sheet of 10 mm steel plate at about 226 kg needs suitable mechanical handling equipment. And a modest concrete slab at 4.8 tonnes explains why slab design is a structural question rather than a DIY one.
| Shape | Volume formula |
|---|---|
| Rectangular block or sheet | length × width × thickness |
| Cylinder or round bar | π × (diameter ÷ 2)² × length |
| Pipe or tube | π × (outer radius² − inner radius²) × length |
| Sphere | (4/3) × π × (diameter ÷ 2)³ |
| Situation | What the number tells you |
|---|---|
| Manual handling | Whether the object can be handled safely or needs lifting equipment. Risk depends on mass, posture, grip, repetition, distance and working conditions — there is no single universally safe lifting limit |
| Freight and delivery | What you will be charged, and whether a vehicle can carry it legally |
| Structural loading | Dead load on a floor, roof or beam — usually converted to kilonewtons |
| Ordering materials | Steel and aggregate are commonly sold by mass, not by piece |
| Water storage | A 5,000 L tank holds 5 tonnes when full, which the stand has to carry |
| Laboratory and physics | Working out an unknown mass from a measured volume and known density |
Three related quantities that are easy to confuse, and three different tools on this site.
| Quantity | Unit | Use this page for |
|---|---|---|
| Mass | kilogram | This page — mass of an object from its material and size |
| Density | kg/m³ | The density calculator — solve for density, mass or volume from any two |
| Weight (force) | newton | The weight and force calculator — gravity, newtons, other planets |
| Unit conversion | kg ↔ lb ↔ stone | The weight converter |
Mass is the amount of matter, and it does not change with location. Weight is the force gravity exerts on that mass, measured in newtons — which is why the calculator above also reports the force in newtons alongside the mass in kilograms.
How do you calculate mass?
Multiply density by volume. Work out the volume from the object's dimensions in metres, then multiply by the material's density in kilograms per cubic metre. A steel plate 2.4 m × 1.2 m × 0.010 m has a volume of 0.0288 m³, and at 7,850 kg/m³ that gives 226.1 kg.
What is the formula for mass?
Mass equals density multiplied by volume, written m = ρV. Rearranged, density is mass divided by volume and volume is mass divided by density — the same relationship solved three ways, which is what the density calculator does.
How much does a steel plate weigh?
Steel is about 7,850 kg/m³, so a standard 2400 × 1200 mm sheet weighs roughly 22.6 kg per millimetre of thickness. A 10 mm sheet is about 226 kg and a 5 mm sheet about 113 kg. Both call for mechanical handling equipment rather than manual lifting.
How much does a concrete slab weigh?
Plain concrete is about 2,400 kg/m³ and reinforced concrete about 2,500. A 5 × 4 m slab 100 mm thick is 2 m³, which comes to 4.8 tonnes plain or 5.0 tonnes reinforced. That is dead load the ground and any supporting structure must carry.
How much does a sheet of plywood weigh?
Plywood averages around 600 kg/m³, so a 2400 × 1200 × 18 mm sheet is about 31 kg. A 12 mm sheet is roughly 21 kg and a 7 mm sheet about 12 kg. Actual weight varies with the species and glue, so treat these as estimates.
How much does a 5,000 litre water tank weigh when full?
About 5 tonnes, since a litre of fresh water is approximately a kilogram. That is comparable to three cars concentrated on the tank's footprint, which is why tank stands and bases are engineered rather than improvised.
Is one litre of water exactly one kilogram?
Close, but not exactly, and not by definition any more. From 1901 to 1964 the litre was defined as the volume of one kilogram of pure water at maximum density, but that was abandoned — a litre is now exactly one cubic decimetre. The actual mass varies with temperature, pressure and purity: around 999.97 g near 4 °C and about 998.2 g at 20 °C. For everyday calculations, treating a litre as a kilogram is accurate to within roughly 0.2%.
How do I calculate the mass of a pipe?
Work out the cross-sectional area as π times the outer radius squared minus the inner radius squared, then multiply by length and density. Do not treat it as a solid bar — for a 6 m length of 100 mm steel pipe with a 5 mm wall, the correct answer is about 70 kg against roughly 370 kg if you assume it is solid.
What is the difference between mass and weight?
Mass is how much matter an object contains, measured in kilograms, and it is the same everywhere. Weight is the force gravity exerts on it, measured in newtons, and it varies with location. This calculator reports both — mass in kilograms and the resulting force in newtons.
Can mass change?
Not by moving an object. Mass changes only if matter is added or removed — through evaporation, corrosion, absorbing moisture or physically cutting material away. Timber gaining water is a common example: the same board can be measurably heavier after rain.
Why do timber and gravel densities vary so much?
Timber density depends on species and moisture content, and the same board can gain 20% or more in mass when wet. Aggregate figures are bulk densities that include the air between particles, so they change with compaction and moisture. Both should be treated as estimates rather than exact values.
What is the SI unit of mass?
The kilogram — the only SI base unit whose name carries a prefix. Since 2019 it has been defined using the Planck constant rather than a physical prototype, meaning it can be reproduced in any suitably equipped laboratory instead of depending on a single cylinder kept near Paris.
Mass from density and volume is simple arithmetic that goes wrong for one reason: unit errors in the volume. Millimetres cubed to metres cubed is a factor of a billion, and that is where the mistakes live.
Choosing a shape and entering dimensions removes that step entirely, which is why this calculator works from material and size rather than asking you to supply a volume you have already had to compute.
For the same relationship solved in any direction, use the density calculator. For converting an existing mass between units, the weight converter.