Updated
March 27, 2026
Reviewed against the current calculator logic, structured content, and internal linking used on BuildCostLab.
Paint quantity tool
Paint Calculator
Estimate paint quantities, tin mixes, and rough material cost for walls, ceilings, and single surfaces.
Methodology
Planning-first estimate
Use this calculator to build a rough material estimate, then confirm it against product coverage data, site conditions, and supplier pack sizes before you order.
Trust
How we publish
See the calculator methodology and editorial policy for the standards behind these pages.
Assumptions
Assumes reasonably flat surfaces, standard coverage rates, and a practical order estimate rather than a bare formula result.
Common mistakes
Common misses include forgetting extra coats, underestimating textured surface loss, and rounding down tin sizes too aggressively.
Best use cases
Useful for repainting rooms, checking ceilings, and estimating feature walls before buying tins.
How to get a better estimate
Measure carefully, apply realistic waste, and sense-check the result against how the product is actually sold.
Before you buy
Round to whole buying units and compare product coverage before buying solely on sticker price.
UK and US note
Unit wording and supplier pack conventions differ between markets, but the estimating logic still starts with geometry, waste, and whole-unit ordering.
Final buying check
Before placing an order, compare product coverage, pack size, delivery cost, and whether buying one extra unit is safer than risking a shortfall.
Explore this topic cluster
Open the full Paint Estimating hub to move from quick estimate to deeper guidance.
How much paint do I need for a room?
Measure the walls or perimeter, apply height and coats, and then add a sensible waste margin.
Should I buy extra paint?
Most buyers round up for cut-ins, touch-ups, and small coverage differences between coats.