Paint Calculator
Work out exactly how many litres and tins of paint you need for any room. Accounts for doors, windows and multiple coats. Covers emulsion, gloss and specialist paints with UK brand coverage rates.
Calculate Paint →Stop guessing and start calculating. Our free tools help you work out exactly how much material you need for any building or home improvement project, saving you money and reducing waste.
Work out exactly how many litres and tins of paint you need for any room. Accounts for doors, windows and multiple coats. Covers emulsion, gloss and specialist paints with UK brand coverage rates.
Calculate Paint →Calculate the number of wallpaper rolls needed for your room, with pattern repeat allowances. Uses standard UK roll sizes (10.05m x 0.53m) and accounts for doors, windows and pattern waste.
Calculate Wallpaper →Find out how many paving slabs, how much sand and sub-base you need for your patio or path. Includes joint spacing, MOT Type 1 sub-base quantities and cement for pointing.
Calculate Paving →Calculate how many tonnes and bulk bags of gravel you need for driveways, paths and garden features. Covers decorative, pea gravel, slate and MOT with UK supplier sizing.
Calculate Gravel →Work out how much concrete you need in cubic metres, ready-mix bags or individual cement, sand and aggregate quantities. Covers slabs, footings and posts with UK Building Regs guidance.
Calculate Concrete →Estimate how many bags of plaster you need and the cost for your project. Supports bonding coat, multi-finish, one-coat and Thistle plaster types with accurate UK coverage rates.
Calculate Plaster →Calculate decking boards, joists, fixings and estimated cost for your garden deck. Covers both softwood and composite decking with UK joist spacing requirements and Building Regs guidance.
Calculate Decking →Work out how many fence panels, posts, postcrete bags and gravel boards you need. Includes UK boundary law guidance, planning permission heights and concrete post requirements.
Calculate Fencing →Calculate how many bricks and how much mortar you need for a wall. Uses standard UK brick sizes (215x102.5x65mm) and covers stretcher, Flemish and English bond patterns.
Calculate Bricks →Find out how much insulation you need and the thickness required to meet UK Building Regs Part L. Covers mineral wool, PIR boards and EPS for loft, wall and floor applications.
Calculate Insulation →Every year, UK homeowners waste millions of pounds on excess building materials. Whether you are painting a bedroom, laying a patio or building a garden fence, ordering the wrong amount of materials leads to wasted money, wasted time and unnecessary trips to the builders' merchant.
According to research by WRAP (the Waste and Resources Action Programme), the UK construction industry generates approximately 62 million tonnes of waste annually, with a significant portion coming from over-ordering materials. While much of this comes from commercial projects, domestic DIY contributes substantially to the problem. The average UK household spends over £1,200 per year on home improvements, and poor material estimation can add 15-25% to that cost.
When you guess how much material you need, you face two costly outcomes. Under-ordering means additional delivery charges, project delays and potential colour batch differences. A second delivery of 20kg bags of concrete or an extra pallet of paving slabs can easily cost £30-£80 in delivery alone. Over-ordering means paying for materials you do not use, storing heavy leftovers and arranging skip hire for disposal. Neither outcome is ideal, and both are entirely avoidable with proper calculation.
Consider a typical patio project using 450x450mm paving slabs. Getting the quantity wrong by just 10% on a 20m² patio means buying 10 extra slabs at roughly £3-£8 each, plus excess sand and cement. For larger projects like fencing a garden boundary or re-rendering an exterior wall, miscalculations of 10-15% can cost hundreds of pounds.
Our free DIY calculators are built using real UK material specifications and industry-standard formulas. Each calculator accounts for the specific characteristics of the materials involved:
Every calculator includes a sensible waste allowance, typically 5-10% for most materials. This covers cutting waste, breakage and minor estimation differences that are inherent in any building project.
To get the most accurate results from our calculators, follow these simple guidelines:
Once you have your quantities, you can source materials from a range of UK suppliers. For general DIY materials, B&Q and Wickes offer good availability and competitive pricing with home delivery. For trade-quality materials, Jewson, Travis Perkins and Buildbase typically offer better prices on bulk orders. Screwfix is excellent for fixings, tools and smaller quantities of building materials. Many independent builders' merchants also offer competitive pricing and local delivery, so it is always worth getting multiple quotes for larger projects.
Many DIY projects in the UK require compliance with Building Regulations, even when planning permission is not needed. Our calculators reference current regulations where relevant, including Part L (energy efficiency) for insulation, foundation depth requirements for structures, and height restrictions for fences and walls. Always check with your local authority if you are unsure whether your project needs Building Regulations approval.
We keep our calculators updated to reflect current material prices, UK Building Regulations and supplier availability. All calculations are performed instantly in your browser, your data is never stored and every tool is completely free to use.