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

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 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.
Preparing the surface — filling, sanding, stripping and the making good that a refurbishment spends more hours on than the painting.
18 calculators
Work out how much block filler an open-textured masonry wall drinks on the first coat, against the data sheet's smooth-substrate rate.
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.
Estimate how many gallons or litres of deck stain or sealer you need to cover your deck.
Estimate how many gallons or litres of exterior paint you need, accounting for rougher-surface coverage rates.
Dust sheets, masking tape and floor protection for a room — counted from the edges and the floor, because tape follows lines and sheeting follows area.
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.
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.
How many containers it takes to blend your tins into one consistent colour, and where the changeover has to fall when they will not all fit in one.
Estimate how much paint you need for a room based on its dimensions, doors, windows, and number of coats.
How many coats it takes to paint light over dark, how much paint that comes to, and how many finish coats a white or tinted primer saves.
How much white or tinting black to add for a stated proportion, what the batch becomes, and why lightening and darkening differ so much in scale.
The volumes of two paints for a chosen ratio, the reduced parts to write on the lid, and a sample batch at that ratio, so the mix can be made again.
Estimate how many gallons or litres of primer you need before painting, using primer's lower coverage rate.
The colourant a batch needs for a stated tint load, scaled from any formula to any batch size, and whether the base you are using can actually carry it.
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.
Sachets of wallpaper paste for a number of rolls, and the water that goes with them — counted the way paste is actually sold.
Estimate how many gallons or litres of stain you need for a wood fence, based on length, height, and sides.
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.