Renovation & Construction

Paint, stain and wallpaper

What a decorator orders, and the arithmetic behind the second coat.

  • 18Calculators
  • 18Work in imperial
  • 18Work in metric

What this covers

Walls, ceilings, woodwork and exteriors by coat; primer and block filler on a surface that will drink the first coat; decking and fence stain; wallpaper by roll and by drop; and the mixing work that comes before any of it — boxing tins together, tinting to a ratio, and lightening or darkening a batch that is not quite right.

What decides which one you need

What is underneath, which decides the coats far more than the colour does. Bare plaster, new board, a dark wall going light, or bare timber outdoors each take a different number of passes, and a spread rate printed on a tin is measured on a sealed surface rather than on any of those. Every page here asks what it is going onto and says which of its figures is the one that moves.

What this does not cover

Preparing the surface — filling, sanding, stripping and the making good that a refurbishment spends more hours on than the painting.

Every calculator in this family

18 calculators

Block Filler Coverage Calculator

Work out how much block filler an open-textured masonry wall drinks on the first coat, against the data sheet's smooth-substrate rate.

Imperial / Metric

Ceiling Paint Calculator

Work out the litres or gallons of paint a ceiling takes from its area, the number of coats and the spread rate on the tin.

Imperial / Metric

Deck Stain Calculator

Estimate how many gallons or litres of deck stain or sealer you need to cover your deck.

Imperial / Metric

Exterior Paint Calculator

Estimate how many gallons or litres of exterior paint you need, accounting for rougher-surface coverage rates.

Imperial / Metric

Metalwork and Railing Paint Calculator

Paint for railings, gates and structural steel from length and girth, the way metalwork is measured, because a balustrade has no area to read off.

Imperial / Metric

Mist Coat Calculator

Paint and water for a mist coat on new plaster — the thinned first coat, split into what you buy and what comes out of the tap.

Imperial / Metric

Paint Calculator

Estimate how much paint you need for a room based on its dimensions, doors, windows, and number of coats.

Imperial / Metric

Paint Primer Calculator

Estimate how many gallons or litres of primer you need before painting, using primer's lower coverage rate.

Imperial / Metric

Wallpaper Calculator

Rolls of wallpaper for a room: US double rolls by wall area, or any roll counted in drops from its length and width, the wall height and pattern repeat.

Imperial / Metric

Wallpaper Paste Calculator

Sachets of wallpaper paste for a number of rolls, and the water that goes with them — counted the way paste is actually sold.

Imperial / Metric

Wood Fence Stain Calculator

Estimate how many gallons or litres of stain you need for a wood fence, based on length, height, and sides.

Imperial / Metric

Woodwork Paint Calculator

Work out the paint for doors, door frames and skirting boards from their sizes and runs, the coats and the spread rate on the tin.

Imperial / Metric

All of Renovation & Construction