Interior Finish Calculators

Material estimates go wrong in two predictable places: forgetting to subtract openings, and forgetting to add waste. These tools do both. The paint calculator deducts doors and windows, accounts for the number of coats and gives coverage per litre or gallon; the tile calculator adds a cut allowance that rises for diagonal layouts, where offcuts pile up fastest.

Order to the figure these give you plus your own margin for error — running short mid-job means a second batch that may not match, which costs more than the extra box would have.