Home Improvement Calculators
Plan your next DIY or renovation project with free home improvement calculators for paint, flooring, tiles, wallpaper, carpet, decking, fencing, garden soil, mulch, pavers and insulation.
Whether you are repainting a bedroom, laying laminate in the living room or building a new deck, the hardest part is knowing how much to buy. Our home improvement calculators take your room or garden measurements and tell you how many litres of paint, boxes of flooring, rolls of wallpaper, bags of mulch or fence panels you need.
Every DIY calculator here is built around how products are actually sold: paint by the litre or gallon, flooring by the pack, wallpaper by the roll and soil by the cubic metre or bag. That means fewer trips back to the store and less money spent on leftovers. For structural work such as slabs, walls and stairs, see our construction calculators.
Paint and wallpaper calculators
Paint coverage depends on the wall area, the number of coats and the paint’s spread rate. Wallpaper depends on roll size and pattern repeat. These tools take all of that into account.
Paint Coverage Calculator
Find how much paint you need from surface area, number of coats and the coverage rate on the tin.
Wall Paint Calculator
Enter room dimensions, doors and windows to get litres or gallons of wall and ceiling paint.
Wallpaper Calculator
Count wallpaper rolls for a room or feature wall, allowing for roll width, length and pattern repeat.
Flooring and tiling calculators
Flooring is sold by the pack or square metre, and tiling needs grout and adhesive as well as tiles. Measure once and get every quantity you need.
Flooring Calculator
Calculate floor area for one or more rooms and the number of packs to buy, with a cutting allowance.
Laminate Calculator
Work out laminate packs, underlay and trims from room size and pack coverage.
Vinyl Flooring Calculator
Estimate sheet vinyl, LVT or vinyl plank flooring, including roll width for sheet vinyl.
Carpet Calculator
Find how much carpet and underlay you need based on room size and standard roll widths.
Tile Grout Calculator
Calculate grout in kg from tile size, joint width, joint depth and area to be tiled.
Tile Adhesive Calculator
Estimate tile adhesive bags from area and bed thickness for floor and wall tiles.
Skirting Board Calculator
Measure the room perimeter minus doorways to get the lengths of skirting or baseboard to buy.
Garden and outdoor calculators
Garden materials are bought in bags, bulk bags or loose loads. These calculators convert your bed or lawn size and depth into the right amount.
Decking Calculator
Plan deck boards, joists and screws for a deck of any size and board width.
Fence Calculator
Count fence posts, panels or pickets, rails and postcrete for a fence line of any length.
Garden Soil Calculator
Find how much topsoil or compost to buy for raised beds, borders and new lawns.
Mulch Calculator
Calculate mulch or bark chippings in bags or cubic metres from bed area and depth.
Lawn Area Calculator
Measure lawn area for turf, grass seed and fertiliser, including irregular shapes.
Paver Calculator
Count block pavers or patio slabs and estimate sand bedding and sub-base for a patio or path.
Driveway Gravel Calculator
Estimate tonnes of driveway gravel and sub-base for a new or resurfaced driveway.
Room and interior calculators
Room Area Calculator
Calculate floor area, wall area and room volume in square metres or square feet, including L-shaped rooms.
Insulation Calculator
Estimate rolls or boards of loft, wall or floor insulation for the area and thickness you need.
Blind Size Calculator
Work out the right blind width and drop for inside-recess and outside-recess fitting.
How to measure for home improvement projects
- Measure each wall or floor separately. Split L-shaped or irregular rooms into rectangles and add the areas together.
- Deduct openings. Subtract doors, windows and built-in units from wall areas when estimating paint or wallpaper.
- Check the product label. Use the coverage per litre, pack size or roll size printed on the product for the most accurate result.
- Allow for waste. Add around 10% for flooring and tiles laid straight, and 15% or more for diagonal or herringbone patterns.
Save money on DIY materials
Overbuying is one of the most common hidden costs in home renovation. A reliable home renovation calculator lets you compare products with different coverage rates or pack sizes, see the real cost per square metre and plan your budget before you shop. Pair these tools with our business and finance calculators, such as the discount and savings goal calculators, to plan the spend.
More home and garden calculators
Drywall Calculator
Estimate drywall sheets, joint compound and screws for a room.
Epoxy Resin Calculator
Work out how much resin and hardener a pour or coating needs.
Sod Calculator
Find how many sod rolls or pallets cover your lawn area.
Square Footage Calculator
Measure the area of rooms and shapes in square feet and square metres.
Frequently asked questions
How much paint do I need for a room?
Add up the wall area (perimeter × wall height), subtract doors and windows, multiply by the number of coats and divide by the coverage on the tin. Many emulsions cover around 10–13 m² per litre per coat, but always check your product. The Wall Paint Calculator does the maths for you.
How much extra flooring should I buy?
Add about 10% for straight-laid flooring to cover cuts and offcuts, and 15% or more for diagonal layouts, herringbone or rooms with many corners.
How deep should mulch be?
A layer of about 5–7.5 cm (2–3 inches) is common for suppressing weeds and holding moisture in beds and borders. The Mulch Calculator converts area and depth into bags or bulk volume.
Can I use these calculators for irregular rooms?
Yes. Divide the space into rectangles, calculate each one and add them up. The Room Area Calculator supports L-shaped rooms directly.
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Planning a project we don’t cover yet?
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