Example with symbolic prices and a stated density
Suppose the verified loose density for the quoted material is 1.6 t/m³ and the required loose quantity is 10 m³. The equivalent mass is 16 t. A quote of R per tonne therefore costs 16R for material, equivalent to 1.6R per m³. Compare 16R + delivery A with 10S + delivery B when the second quote is S per loose m³. No local market price is assumed.
Confirm that the offers describe the same material
Record the product, grading, moisture or delivery condition where relevant, and whether the quote is for a loose or compacted quantity. Different aggregate products are not made equivalent simply by converting their units. Confirm the specification before comparing price.
A supplier may quote a truckload, tonne, cubic metre or bag. Ask what each sale unit contains and whether the quantity is measured, nominal or capacity based. A 'load' without a stated usable quantity is not yet a comparable unit rate.
Use the matching bulk density
Mass in tonnes = volume in m³ × bulk density in tonnes/m³. For the reverse conversion, divide mass by density. The bulk density must describe the same material condition as the volume. Solid particle density would ignore the voids within a loose pile and is the wrong input.
If a measured supplier value is unavailable, leave the comparison as a sensitivity scenario and label it unresolved. Do not present an assumed density as a verified conversion or a universal property of sand, gravel or road base. Moisture and handling can affect the delivered basis.
Normalize the rate, then calculate the order
If quote A is R monetary units per tonne and the matching verified density is d tonnes/m³, its material-only rate is R × d per m³. Compare that with quote B's rate for the same cubic-metre basis. Keep the monetary currency identical or use a stated conversion date and method.
Apply the actual order quantity and package rules next. Minimum loads, full bags and delivery increments may change the payable quantity. A lower normalized unit rate can still produce a higher total when minimum orders or fixed delivery charges differ.
Do not confuse loose supply and compacted design volume
An in-place base layer measured as area × compacted depth gives compacted volume. A loose-delivered quote needs the appropriate verified relation to that volume. Converting directly with a loose density without resolving compaction mixes two different conditions.
Keep preparation, installation, compaction and disposal separate from material supply unless the offer includes them. Save quote dates, validity, density evidence, quantity basis and delivery scope. Compare an actual project total that another buyer can reproduce, not just the smallest number in the rate column.
Do it in order
- Align product specification, condition, currency and quote date.
- Convert between tonnes and cubic metres using the corresponding documented bulk density.
- Apply purchase rounding, minimum orders and delivery charges to compare total payable amounts.
Planning boundary
This is a unit and scope comparison. It does not verify material suitability, supplier density or local market prices.
Sources checked
Is a tonne the same as a cubic metre?
No. A tonne measures mass and a cubic metre measures volume. Their relationship requires the matching material density.
Can I compare one quote for compacted m³ and one for loose m³ directly?
No. Resolve the volume-condition relationship first, then compare quantities and rates on the same basis.