Calculate litres or US gallons, tins, flooring packs, tiles and boxes for one or multiple rooms. Choose Paint for walls and ceilings, Flooring for floor areas, or Tile for floors and walls; use the direct-area option when you have already measured the surface.
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Results
Ready when you are
Add at least one room/area to see totals.
Tip: Use whole room sizes; exact skirting/corners are handled by waste/cuts %. Round up products for safety.
How the calculator works
Paint: Walls area = perimeter × height minus openings. Ceiling is length × width. Multiply by coats, then divide by coverage (m² per litre). Tins round up.
Flooring: Area = length × width. Add waste %, divide by pack coverage, round up packs.
Tiles: Effective tile size = tile + spacing on both edges. Tile count = area ÷ effective tile area, add waste %, round up tiles/boxes.
Best Practices for Paint, Flooring & Tiling
Paint: prep smart for smoother coats
Surface prep first: Fill, sand, and dust off. Grease or gloss? Clean, then lightly sand to key the surface. Fresh plaster should be dry and mist-coated (diluted first coat) before full coats.
Primer matters: Use stain-blocking primer over knots, water marks, or marker. On bare wood, use appropriate wood primer; on shiny trim, an adhesion primer prevents peeling.
Right tools: Walls: medium-pile roller; ceilings: longer pile; doors/trim: quality synthetic brush. Extendable poles improve speed and posture.
Cut in + roll: Cut the edges, then roll while the cut line is still wet to avoid “picture framing.” Work one wall at a time.
Coats & coverage: Most emulsions cover ~10–12 m²/L (check the tin). Dark colours or drastic colour changes often need an extra coat or tinted primer.
Dry times & ventilation: Respect recoat times; high humidity slows curing. Keep rooms ventilated. Choose low-VOC paints for better indoor air quality.
Openings & ceilings: Subtract doors/windows from wall area; add the ceiling if you’re refreshing the room fully. Our calculator handles both.
Safety: Masking, dust extraction, eye protection, and stable ladders beat speed every time.
Flooring: stable base, tidy finish
Check flatness: Subfloors should be clean, dry, and level to the manufacturer’s tolerance. Use a straightedge; self-levelling compound can fix dips.
Moisture testing: Concrete must be dry enough for the floor type or a suitable DPM (damp-proof membrane) is required. Timber subfloors need to be sound and fixed.
Acclimatise boards: Many laminates/engineered boards need 24–48 hours in the room before fitting. Keep packs flat and sealed per instructions.
Underlay & expansion: Choose underlay for acoustic, thermal, and moisture needs. Leave expansion gaps (often 10–12 mm) around edges and fixed objects; use trims to cover.
Layout planning: Dry-lay the first few rows and aim to avoid slivers (<60 mm). Stagger end joints (e.g., by ≥300 mm) for strength and aesthetics.
Waste allowance: Straight planks typically need 5–10% extra; complex layouts or herringbone may need more. Our tool defaults to 10% but you can adjust.
Tiling: crisp lines, long-lasting installs
Substrate & waterproofing: Use tile-backer boards where possible; in wet zones (showers), tank the area. Flexible, cement-based adhesive is common for most substrates.
Plan the grid: Find the centre lines and dry-lay to avoid tiny cuts at edges. Use spacers matched to tile size and style (e.g., 2–3 mm for rectified porcelain; larger for rustic tiles).
Large-format tips: Back-butter tiles >300 mm for better coverage. Consider a levelling clip system to minimise lippage.
Movement joints: Honor building movement—leave perimeter gaps and use silicone (not grout) at changes of plane. Use expansion profiles on large runs per standards.
Cuts & edges: Plan trims (metal or PVC) at external corners and exposed edges. Allow extra waste (often 10–15%) for patterned layouts or heavy cutting.
Grout & sealing: Choose grout type for joint width and traffic. Seal natural stone and some grout types as specified; follow cure times before wet use.
Slopes & drains: Wet rooms need consistent falls toward the drain—confirm before tiling; don’t try to “tile in” large height corrections.
Eco & aftercare
Low-VOC choices: Select low-odour, low-VOC paints and adhesives where possible.
Dispose responsibly: Don’t pour leftover paint or adhesive down drains. Many councils offer paint recycling or special waste facilities.
Maintenance: Use felt pads under furniture on new floors, avoid steam mops if the manufacturer forbids them, and clean grout with pH-appropriate products.
Use the calculator above to size materials, then round up sensibly for colour matching and batch consistency. When in doubt, follow the manufacturer’s datasheet for the exact product you’re using.
📐 5 Fun Facts about Coverage
1
Rooms aren’t perfect boxes
Paint coverage is usually based on flat rectangles, but real walls have cornices, nibs, and alcoves. Adding 5–10% “fudge” often saves a last-minute tin run.
Real-world buffer
2
Ceilings eat more paint
Fresh plaster, high humidity, or ceilings with texture can drop coverage by 10–20% compared with the tin’s headline number.
Hidden soak
3
Board widths change waste
Wide flooring planks mean fewer seams and usually less waste; skinny planks or herringbone patterns can push waste well beyond the default 5–10%.
Pattern penalty
4
Grout lines shrink tiles
A 600×600 mm tile with a 3 mm grout line effectively covers about 603×603 mm. Tiny joints add up across a room and can change box counts.
Spacing math
5
Batch colours can drift
Paint and tile batches vary slightly. Buying a little extra up front improves colour match for touch-ups or replacements months later.
Match insurance
Measuring, allowances and worked examples
Measure rectangles separately and add alcoves; subtract fixed islands or cabinets. Allow 5–10% for straight flooring, 10% for straight tile, and 15–20% for diagonal or herringbone layouts. Paint commonly covers 10–14 m²/L per coat; porous or textured surfaces may cover less, so prefer the product label.
Bedroom paint
A 4 × 3 m room, 2.4 m high, with a 0.8 × 2 m door and 1.2 × 1.2 m window has 2(4 + 3) × 2.4 − 3.04 = 30.56 m² of wall. Two coats at 12 m²/L need 30.56 × 2 ÷ 12 = 5.09 L; buy three 2.5 L tins.
Irregular laminate floor
Rectangles of 4 × 3 m and 1.5 × 1 m total 13.5 m². With 10% waste that is 14.85 m²; ⌈14.85 ÷ 2.2⌉ = 7 packs, purchasing 15.4 m².
Bathroom wall tiles
A 3 × 2.4 m wall is 7.2 m². At 300 × 600 mm, 7.2 ÷ 0.18 = 40 tiles; 10% waste gives 44. At 8 per box, buy 6 boxes (48), leaving 4.
Coverage calculator FAQs
How much area does one litre of paint cover?
Typical interior paint covers 10–14 m²/L per coat (about 408–571 ft²/US gal). Use the product label.
Do two coats double the paint quantity?
Yes. Multiply paintable area by two before dividing by coverage.
Should I subtract doors and windows?
Subtract large openings. Small openings are often left in because cutting-in and surface variation use part of the saving.
How much flooring or tile waste should I add?
Use 5–10% for straight flooring, 10% for straight tile, and 15–20% for diagonal, patterned or herringbone layouts.
Do grout gaps count toward tile coverage?
No for purchasing: use tile face area. Spacing is useful for rows and columns only.
How are boxes calculated, and should I keep leftovers?
Divide the adjusted requirement by the contents of one box and round up. Keep matching leftovers for repairs.
