DIY calculators that show their working

Work out the paint, tiles, concrete or timber to buy before you go to the DIY shop or builders’ merchant. Every calculator explains the maths and the assumptions behind it.

Walls and ceilings

Paint, wallpaper and plasterboard for a room.

Paint Calculator How many litres and tins of paint for walls and ceilings, allowing for doors, windows and coats.Wallpaper Calculator Rolls of wallpaper for a room or a single wall, allowing for the pattern repeat, doors and windows.Plasterboard Calculator Sheets of plasterboard for walls and ceilings, with an allowance for offcuts.

Floors and tiling

Room area in square metres, tiles and flooring packs.

Tile Calculator Tiles and boxes for a floor or wall, allowing for grout joints and cuts.Flooring Calculator Packs of laminate, vinyl or wood flooring for a room, plus underlay and skirting board.Square Metre Calculator Floor area of rooms of any shape in square metres, with square feet alongside.

Garden and concrete

Concrete bases, footings, mulch, topsoil and gravel.

Concrete Calculator Concrete for bases, footings and fence posts, in cubic metres and in bags.Topsoil, Mulch and Gravel Calculator Topsoil, bark mulch, compost or gravel for a bed or border, in bags, cubic metres or tonnes.

Timber, stairs and roofs

Timber quantities, staircase layout and roof pitch.

Timber Calculator Cubic metres, linear metres and cost of timber from its size in millimetres, length and price.Stair Calculator Number of steps, rise, going, pitch and string length, checked against Approved Document K.Roof Pitch Calculator Convert roof pitch between degrees, percent and rise over run, then work out rafter length and roof area.

More tools in US English

These tools are written for the United States, use US units and are only available in US English.

Feet and Inches Calculator ENAdd, subtract, multiply and divide feet-and-inches measurements with fractions of an inch, and convert them to metric.

How these calculators work

The formula is on the page

Each calculator explains how the result is worked out, with an example you can check by hand.

Figures come with a source

Coverage rates, product sizes and building regulations link to the page we checked and the date we checked it.

What you type stays on your device

Everything is calculated in your browser. There is no account to create and nothing you type is sent to us.