Tile & Grout Calculator

Tiling Guide

Waste Allowance by Pattern

Straight grid pattern: 10% waste allowance. Offset / brick bond (each row shifted by half a tile): 10–12% waste — the offset cuts increase edge waste slightly. Diagonal / 45° pattern: 15–20% waste — cutting tiles to fit a diagonal layout produces significantly more offcuts. Herringbone: 15–20% waste. For complex shapes or rooms with multiple features (bays, alcoves, columns): add an additional 5%. Always buy tiles from the same batch (same batch number on box) — colours and sizes vary between pr

Grout and Adhesive Calculations

Grout quantity depends on tile size, gap width, and tile depth. A rough guide: for 300×300mm tiles with 3mm gaps, approximately 0.5–0.8kg grout per m². For larger tiles (600×600mm): approximately 0.3–0.5kg per m². Tile adhesive: standard coverage is 3–4kg per m² for standard adhesive (notched trowel application). For large-format tiles (over 600mm), use flexible adhesive and back-butter the tile as well. Always apply adhesive in one direction with a notched trowel — this ensures consistent cover

Surface Preparation

Tiling over paint: remove all loose paint, sand to rough up, prime with a tile primer (PVA + water will not bond adequately). Tiling over plasterboard: use waterproof tile backer boards in wet areas (shower, bath), not standard plasterboard — moisture causes the plasterboard to swell and the tiles to lift. Over existing tiles: possible if tiles are fully adhered, level, and sound — check by tapping (hollow sound = loose). Use a tile primer and flexible adhesive. Over floors: must be solid, level

Setting Out and Starting Point

Never start tiling from a corner — corners are never truly square, causing tiles to splay out visibly. Find the centre of the wall or floor using chalk lines, set out from the centre, and adjust so that cut tiles at the edges are equal width (and ideally over half a tile wide). For floors, 'dry lay' tiles across the room first to check your layout visually before committing adhesive. Use tile spacers consistently — even 1mm variation in gaps is visible. Diagonal patterns start from the exact roo