Concrete Calculator

ConstructionInstant resultsFormula shown100% in your browser

Work out concrete volume for slabs, beams, columns and footings, with cement bags, sand and aggregate quantities for any nominal mix.

Inputs

Length (m)

Width (m)

Depth / thickness (m)

Nominal mix ratio (cement : sand : aggregate)

Presets follow IS 456 nominal mixes — pick the grade or the ratio you were given on site.

Wastage allowance (%)

Water–cement ratio

How to use this calculator: Concrete Calculator

Work out concrete volume for slabs, beams, columns and footings, with cement bags, sand and aggregate quantities for any nominal mix. The example below is calculated by this page's real engine from the displayed inputs.

1Confirm that the Concrete Calculator matches the quantity or design check you need.
2Enter Length, Width, and Depth / thickness using the units printed beside each field.
3Select the applicable Nominal mix ratio (cement : sand : aggregate) options; these choices change the calculation method or factors.
4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.

Input guide and example values

Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.

Input	Example value	Why it matters
Length	5 m	Measured or known length used by the calculation engine.
Width	4 m	Measured or known width used by the calculation engine.
Depth / thickness	0.15 m	Measured or known depth / thickness used by the calculation engine.
Nominal mix ratio (cement : sand : aggregate)	M20 — 1 : 1.5 : 3	Presets follow IS 456 nominal mixes — pick the grade or the ratio you were given on site.
Wastage allowance	5 %	Measured or known wastage allowance used by the calculation engine.
Water–cement ratio	0.5	Measured or known water–cement ratio used by the calculation engine.

Formula inputs & variables for Concrete Calculator

These are the named quantities used by this calculator. When the source formula does not define a mathematical symbol, OneCalcApp keeps the real input label instead of inventing one.

Variable / input	Unit	Meaning in this calculation
Length	m	Measured or known length used by the calculation engine.
Width	m	Measured or known width used by the calculation engine.
Depth / thickness	m	Measured or known depth / thickness used by the calculation engine.
Nominal mix ratio (cement : sand : aggregate)	—	Presets follow IS 456 nominal mixes — pick the grade or the ratio you were given on site.
Wastage allowance	%	Measured or known wastage allowance used by the calculation engine.
Water–cement ratio	—	Measured or known water–cement ratio used by the calculation engine.

Formula, derivation and worked example

Fresh concrete occupies less space than its dry ingredients because sand fills the voids between aggregate and cement paste fills the voids in sand. The accepted bulking factor is 1.54 for nominal mixes. Ingredient volumes then follow the mix proportions, and cement volume converts to 50 kg bags using a bulk density of 1440 kg/m³.

Wet volume = L × W × D

Dry volume = wet volume × 1.54

Cement volume = dry volume × 1 / (a + b + c); bags = cement volume × 1440 / 50

Sand = dry volume × b / Σ; Aggregate = dry volume × c / Σ

Substitution steps

1. Wet volume incl. wastage
L × W × D × (1 + waste)
= 3.15 m³
2. Dry volume
wet × 1.54
= 4.851 m³
3. Cement volume
dry × 1/5.5
= 0.882 m³
4. Cement bags
volume × 1440 / 50
= 25.4 bags
5. Sand
dry × 1.5/5.5
= 1.323 m³
6. Aggregate
dry × 3/5.5
= 2.646 m³

Computed example results

Concrete volume (wet): 3.15 m³; 111.24 ft³
Dry volume: 4.851 m³
Cement: 25.4 bags; 1,270 kg
Sand: 1.323 m³; 2,117 kg approx.
Coarse aggregate: 2.646 m³; 3,969 kg approx.
Water: 635 litres; w/c = 0.5
Concrete mass: 7,560 kg

Understanding the result

Read the main result together with supporting checks, assumptions, limits and intermediate values.

For a manual check, repeat the first equation, confirm the units and change one input at a time.

Common mistakes when using Concrete Calculator

Do not mix units for Length (m), Width (m), Depth / thickness (m). A unit mismatch changes the input magnitude even when the typed number looks reasonable.
Do not leave Nominal mix ratio (cement : sand : aggregate) on the default choice unless that choice matches the real scenario; the selected option can change the calculation path or factor.
Do not replace the displayed Wet volume = L × W × D relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
Do not treat Concrete volume (wet) = 3.15 m³ from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.

When the Concrete Calculator is useful

Concrete Calculator is designed for cases where Length, Width, Depth / thickness, Nominal mix ratio (cement : sand : aggregate) are known and you need Concrete volume (wet), Dry volume, Cement. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.

Use the calculator for the scope described by its inputs and notes. The displayed method is Wet volume = L × W × D. If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.

Length and Width: what changes the answer

The worked example uses Length = 5 m, Width = 4 m, Depth / thickness = 0.15 m, Nominal mix ratio (cement : sand : aggregate) = M20 — 1 : 1.5 : 3. With those values, Concrete volume (wet) is 3.15 m³. Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.

For this calculator, the main input roles are: Length (m): Measured or known length used by the calculation engine. Width (m): Measured or known width used by the calculation engine. Depth / thickness (m): Measured or known depth / thickness used by the calculation engine. Nominal mix ratio (cement : sand : aggregate): Presets follow IS 456 nominal mixes — pick the grade or the ratio you were given on site. Available choices include M5 — 1 : 5 : 10, M7.5 — 1 : 4 : 8, M10 — 1 : 3 : 6, M15 — 1 : 2 : 4.

How to sanity-check a Concrete Calculator result

Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Concrete volume (wet), because it is the first worked-example output shown by the live engine.

Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.

Next logical calculator

Continue with Cement Calculator

Cement Calculator is directly connected from Concrete Calculator as a source-defined continuation or comparison.

Open Cement Calculator

Standards, source trail and limitations

References show the method used. Check the current local edition, amendments and project specification before a regulated decision.

Formula

Wet volume = L × W × D
Dry volume = wet volume × 1.54
Cement volume = dry volume × 1 / (a + b + c); bags = cement volume × 1440 / 50
Sand = dry volume × b / Σ; Aggregate = dry volume × c / Σ

Engineering notes

Unit notes: 1 m³ = 35.315 cu ft; 1 brass = 100 cu ft = 2.832 m³. Sand is about 1,600 kg/m³ and 20 mm aggregate about 1,500 kg/m³, so 1 m³ of sand ≈ 1,600 kg and 1 brass of sand ≈ 4.53 tonnes.
Nominal mixes are written cement : sand : aggregate by volume. 1:2:4 is M15, 1:1.5:3 is M20 and 1:1:2 is M25 — the grade names and the ratios describe the same mix.

Cement, sand and aggregate per 1 m³ of concrete

Dry volume factor 1.54, cement 1440 kg/m³ (50 kg bags), sand 1600 kg/m³, 20 mm aggregate 1500 kg/m³. Multiply by your wet volume in m³.

Grade	Mix ratio	Cement (bags)	Cement (kg)	Sand (m³ / kg)	Aggregate (m³ / kg)
M5	1 : 5 : 10	2.77	138	0.481 / 770	0.963 / 1444
M7.5	1 : 4 : 8	3.41	171	0.474 / 758	0.948 / 1422
M10	1 : 3 : 6	4.44	222	0.462 / 739	0.924 / 1386
M15	1 : 2 : 4	6.34	317	0.440 / 704	0.880 / 1320
M20	1 : 1.5 : 3	8.06	403	0.420 / 672	0.840 / 1260
M25	1 : 1 : 2	11.09	554	0.385 / 616	0.770 / 1155

Worked example

1Slab 5 m × 4 m × 0.15 m → wet volume = 3.0 m³.
2Dry volume = 3.0 × 1.54 = 4.62 m³; for M20 (Σ = 5.5) cement = 4.62/5.5 = 0.84 m³.
3Cement = 0.84 × 1440 / 50 = 24.2 bags; sand = 1.26 m³; aggregate = 2.52 m³.

Assumptions

Bulking factor 1.54 for dry volume, cement bulk density 1440 kg/m³, 50 kg bags.
Nominal volumetric mixes to IS 456; design mixes must come from a mix design report.

Tips

Order ready-mix in 0.5 m³ steps and always include the wastage allowance.
One cubic metre of M20 concrete weighs about 2400 kg — check slab loading before pouring.

Warnings

Nominal mixes are permitted only up to M20 under IS 456. Above that, use a designed mix.
A water–cement ratio above 0.55 sharply reduces durability and strength.

Standards & references

IS 456:2000
IS 10262 (mix design)
IS 383 (aggregates)

Frequently asked questions

How many cement bags are in 1 m³ of M20 concrete?

About 8.06 bags of 50 kg, i.e. 403 kg of cement, based on a dry volume factor of 1.54 and a 1 : 1.5 : 3 mix.

Why multiply the wet volume by 1.54?

Because dry ingredients bulk up: voids in aggregate and sand are filled during mixing, so 1.54 m³ of dry material yields roughly 1 m³ of compacted concrete.

What water quantity do I need?

Water = w/c ratio × cement mass. At w/c 0.5 with 403 kg of cement you need about 202 litres per cubic metre.

What is a 1 : 2 : 4 concrete mix?

One part cement, two parts sand and four parts coarse aggregate by volume — the nominal M15 mix. Per cubic metre it needs about 6.34 bags of cement (317 kg), 0.44 m³ of sand and 0.88 m³ of aggregate.

Which mix ratio is M20 and M25?

M20 is 1 : 1.5 : 3 and M25 is 1 : 1 : 2 by volume. IS 456 allows nominal mixes only up to M20; M25 and above should come from a design mix.

How do I convert 1 m³ of sand or aggregate to kg?

Multiply by the bulk density: sand ≈ 1,600 kg/m³, so 1 m³ of sand is about 1,600 kg (1.6 tonne); 20 mm aggregate ≈ 1,500 kg/m³. One brass (100 cu ft = 2.832 m³) of sand is roughly 4.53 tonnes.

What inputs does the Concrete Calculator use?

It uses Length, Width, Depth / thickness, Nominal mix ratio (cement : sand : aggregate), Wastage allowance, and Water–cement ratio. Follow the unit printed for each field and choose any selectable option to match the real scenario.

What does the Concrete Calculator calculate?

It calculates Concrete volume (wet), Dry volume, Cement, Sand, Coarse aggregate, Water, and Concrete mass. With the displayed default inputs, Concrete volume (wet) is 3.15 m³.

Related calculators

Keep going with more construction tools.

Cement Calculator

Cement, sand and water quantities for plastering, flooring screed and masonry mortar — in bags, kilograms and cubic metres.

Brick Calculator

Estimate the number of bricks, mortar volume, cement bags and sand needed for any wall from its area and thickness.

Steel & Metal Weight Calculator

Calculate MS plate, TMT rod, pipe, flat, square bar and angle weight from dimensions, quantity, density, wastage and Indian ₹/kg rates.

Underground Water Tank Calculator

Work out how many litres an underground sump holds from its length, width and depth — and how many days it will last.

Sand Quantity Calculator

Find how much sand you need for concrete, plaster or masonry in cubic feet, cubic metres, tonnes and tractor loads.

Aggregate Quantity Calculator

Calculate the coarse aggregate (jelly / metal) needed for a concrete job in cubic feet, cubic metres and tonnes.