Concrete

Cement, sand & ballast calculator

Estimate cement, sand and ballast quantities from a chosen mix ratio, volume, allowance and whole bag rounding.

Transparent formulaFormula v1.0 · selected wet volume × waste allowance × dry-volume factor ÷ chosen mix parts

01Enter your measurements

Enter measurements, then review the audit trail before you buy.

Units

Concrete mix quantity

Start with the wet mix volume you want to make. The tool splits a chosen ratio; it does not choose a mix for you.

Wet mix volume m³Waste allowance %Extra material for cuts, breakage or handling. Enter 8 for 8% extra; use 0 for none.Cement : sand : ballast partsCement bag size kgSand / ballast bulk bag m³

Advanced planning assumptions

These visible assumptions affect the estimate. Change them only if you have product-specific values.

Dry-volume factor Planning factor applied to the allowance-adjusted wet volume.Cement density assumption kg/m³Visible planning input used to convert cement volume to kilograms.

02Materials estimate

Enter measurements to calculate.

Calculated requirement → waste allowance → recommended order → purchasable units

Calculated wet requirement—

Waste allowance—

Recommended wet volume—

Dry-volume planning amount—

Cement bags—

Sand bulk bags—

Ballast bulk bags—

Formula v1.0 · selected wet volume × waste allowance × dry-volume factor ÷ chosen mix parts · Round purchasable units up to a whole pack, bag or unit where selected.

No account or cloud storage — a saved draft stays in this browser.

Project / reference optional Notes for a merchant optional

Early access

Check supplier pricing

Supplier pricing is being prepared. Create the list first, then use it to ask a local merchant for price, stock, delivery and lead time. No contact details or measurements are sent.

Next steps

Product options · Not connected

Buy what you need

Product options are not connected. Use the calculated list with the product details you choose.

Compare merchants · Not connected

Compare merchants

Merchant prices, availability and comparison data are not connected.

Professional quote option · Not connected

Get professional quotes

Quote routing is not available. Create a quote-ready materials list to discuss with a merchant.

Scope boundary: Mix-quantity estimate only — it does not choose a mix or determine specialist project decisions.

Check the path

Your calculation audit

Every total is shown as a short sequence so you can see what was measured, deducted, adjusted and rounded.

01
Awaiting valid measurementsComplete the fields above to reveal the formula path.
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Measure clearly

Simple guidance

Enter the wet mix volume you want to make, select the parts ratio you intend to use and review the visible dry-volume factor. The tool divides that planning quantity between cement, sand and ballast, then rounds the purchase units you selected.

Measure the finished surface or internal clear dimensions. Keep a note of any deduction you make.

Worked example

Follow the same logic

For 0.6 m³ of wet mix, a 10% allowance gives 0.66 m³. With a visible 1.54 dry-volume factor and a selected 1:2:4 ratio, the plan estimates about 209 kg of cement and rounds to nine 25 kg bags, plus one 0.85 m³ bulk bag each of sand and ballast.

Planning tipWrite down the product factor or pack size you used, so a later change is easy to trace.

Before you buy

Three quick checks

01
Enter the wet volume you have independently chosen to make.
02
Keep the dry-volume factor, mix parts and cement-density assumption visible.
03
Confirm bag and bulk-bag sizes with the merchant before buying.

Quick answers

Useful to know

Does this select a mix for my project?

No. Choose the mix independently. This tool only turns the ratio and material-volume inputs you provide into an approximate purchase list.

Why is there a dry-volume factor?

The selected factor makes that planning assumption visible before the parts ratio is split. You can change it when you have a product-specific value.

Review record

Transparent calculation method

Last reviewed: 2026-10-17. Formula version: v1.0. Classification: mix-quantity estimate; does not choose a mix for a project.

Formula source: src/calculator-core.mjs#cementSandBallastPlan. The dry-volume factor, density, parts ratio and bag sizes are visible planning assumptions that the visitor can change.

Read methodology