Interior & Decorating Calculators

Free calculators for UK interior and decorating jobs — paint, wallpaper, wall and floor tiles, plasterboard and skim, coving and electrical cable sizing. Each tool factors in coverage rates, pattern repeats, grout joints and cutting waste for an accurate materials list.

Interiors
Paint Calculator
Walls, ceiling and woodwork. 8 paint types, interactive wall selector, tin optimiser, mist-coat guide and woodwork trim.
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Interiors
Wallpaper Calculator
Roll count accounting for pattern-match type and repeat length.
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Interiors
Wall & Floor Tile Calculator
Tile count for any room, factoring in grout joints and cutting waste.
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Interiors
Plaster & Board Calculator
Plasterboard sheets and skim-plaster bags for walls and ceilings.
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Interiors
Coving Calculator
Exact coving lengths (2m or 3m), adhesive bags or tubs, joints and cutting wastage.
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Interiors
Electrical Cable Size Calculator
Minimum cable cross-section for safe power delivery over any run length.
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How these calculators work

Interior jobs are decided by coverage rates and waste, not floor area. The paint calculator works per coat by paint type and includes mist-coat guidance for new plaster; wallpaper accounts for pattern repeat and match type; and tiling factors in grout joints and cutting waste rather than assuming perfect coverage. The electrical cable sizing tool follows BS 7671 to give the minimum safe cross-section for a given load and run length.