Units are converted before calculation
The calculation core uses metres, square metres, cubic metres, litres and kilograms. Inputs entered in imperial units are converted to the corresponding metric values before the formulas run. Results can then be presented in the selected measurement system.
An inch is 0.0254 metres and a foot is 0.3048 metres. Area and volume use squared and cubed conversion factors. A US liquid gallon is 3.785411784 litres; an Imperial gallon is a different unit and is not the gallon used by these tools. NIST conversion references are linked on the relevant calculator pages.
Coverage and waste are separate
Area calculations begin with the gross rectangle and subtract the excluded area. The tile, paint, concrete, flooring and brick tools then apply the entered allowance as a multiplier: 1 + percentage ÷ 100. This makes the addition visible instead of changing the original measurement.
Defaults are worked starting examples, not product recommendations. Use the chosen product’s coverage, dimensions or pack size and an allowance appropriate to the layout. Irregular shapes must be divided into suitable simpler sections.
Rounding follows the purchase quantity
Tile, brick and flooring pack counts round upward to complete units. Paint shows its calculated volume and a quantity rounded upward to the next 0.1 litre for transfer to a quotation. You still need to select the manufacturer’s available container sizes.
Displayed decimal precision is a presentation choice, not a claim about measurement accuracy. Small differences can arise when rounded display values are compared with a calculation that retains additional decimal places internally.
Glass weight uses an explicit density
The flat-glass calculation uses 2,500 kg/m³, equivalent to approximately 2.5 kg per square metre per millimetre of glass thickness. It treats each entered panel as a rectangle of uniform thickness. Frames, fittings, cavities and laminated interlayers are not included.
The result estimates mass. It does not evaluate glass strength, supporting hardware, installation suitability or a handling procedure.
Costs come from your inputs
Material cost is quantity multiplied by unit rate. The material discount reduces that subtotal, and the entered tax percentage applies to the discounted material amount. Labour and transport are added afterward, without an additional tax or discount calculation. Enter those service amounts inclusive of any applicable service taxes.
The quotation builder uses the same simple calculation order for its material line-item subtotal. For different tax rates, exemptions or another pricing arrangement, use an itemisation and calculation that matches the actual requirements. A currency selector labels amounts and does not provide exchange-rate conversion.
Check assumptions before relying on a result
We check the calculation core against worked examples and boundary cases, including unit conversions and whole-unit rounding. Those checks establish the intended arithmetic; they cannot verify a user’s site dimensions, product choice or applicable local requirements.
Before placing an order, review the measurements, exclusions, product data, allowance and supplier purchase increments. Read the formula and example on the calculator page if a result differs from what you expected.