Home & DIY Calculators (US & UK Units)
Work out exactly how much material to buy before you start a project. Every calculator works in US units (feet, inches, pounds, gallons) and UK metric units (metres, millimetres, kilograms, litres), and explains the maths behind the answer.
Concrete & landscaping
Interior
- Paint Calculator Gallons or litres of paint for walls and ceilings.
- Square Footage Calculator Area of rooms and plots in ft², m², yd² and acres.
- Flooring Calculator Boxes of laminate, vinyl or wood flooring, with waste.
- Tile Calculator Floor and wall tiles, including grout joints and waste.
- Drywall & Plasterboard Calculator Sheets of drywall or plasterboard for walls and ceilings.
Exterior
Planning a project: measure once, buy once
Most DIY overspend comes from two mistakes: buying too little and paying for a second delivery, or buying far too much and being unable to return it. A few habits avoid both.
- Measure in the unit you will buy in. US stores sell concrete by the pound and the cubic yard, paint by the gallon and flooring by the square foot. UK merchants sell by the kilogram, tonne, litre and square metre. Switch the calculator to match your store and the answer will line up with the shelf.
- Add the right waste allowance. Around 5–10% for concrete, gravel and straight-laid flooring, and 15% or more for diagonal tiling or herringbone patterns, where more pieces are cut.
- Round up to whole packs. Every calculator here rounds up to whole bags, boxes, tins or sheets, because that is what you actually have to buy.
- Check the label. Coverage and yield vary between brands. If your product lists a different figure, use it — most calculators let you change the coverage or pack size.
Every calculator shows the formula it uses and a worked example in both US and UK units, so you can check the numbers yourself.