Pick whichever tool fits what you're working on. All calculators are free, use 2026 UK data, and work on any device.
Lawn Care
Grass Seed Calculator
New lawn, overseeding, different seed types — enter your measurements and it does the maths. No more guessing bags at the garden centre.
Calculate now →Lawn Feed Calculator
Too much feed burns grass. Too little wastes money. Gets you the right amount for your lawn size and product.
Calculate now →Fertiliser Calculator
Work out the right amount of fertiliser for your garden beds, borders and containers based on NPK ratios.
Calculate now →Soil, Mulch & Compost
Topsoil Calculator
Calculate how much topsoil you need for raised beds, borders, lawns and garden beds. Shows litres, bags and bulk bags.
Calculate now →Mulch Calculator
Calculate how much mulch you need for beds, borders and paths. Supports bark, wood chip and decorative gravel.
Calculate now →Compost Calculator
Work out how much compost you need for raised beds, pots and borders. Includes green/brown ratio guidance.
Calculate now →Gravel Calculator
Calculate how much gravel, pea shingle or decorative stone you need for driveways, paths and garden areas. Shows tonnes and bags.
Calculate now →Paving Calculator
Work out how many paving slabs you need for your patio, path or driveway. Supports all standard UK slab sizes.
Calculate now →Turf Calculator
Calculate how many rolls of turf you need for your lawn. Shows rolls, cost estimate, and topsoil needed for preparation.
Calculate now →Concrete Calculator
Calculate how much concrete you need for slabs, paths, shed bases and fence posts. Shows postcrete and ready-mix bag counts.
Calculate now →Decking Calculator
Work out how many decking boards, joists and screws you need. Covers softwood and composite in standard UK sizes.
Calculate now →Fencing Calculator
Calculate how many fence panels, posts and bags of Postcrete you need. Covers lap, closeboard and feather edge panels.
Calculate now →Sub-Base Calculator
Calculate MOT Type 1, crusher run or scalpings for driveways, patios, paths and shed bases. Shows tonnes and bulk bags.
Calculate now →Tarmac Calculator
Calculate tarmac or asphalt for driveways, paths and car parks. Shows tonnes, hot-mix loads and cost estimate.
Calculate now →Bark Chippings Calculator
Calculate bark chippings for paths, play areas, driveways and borders. Includes BS EN 1177 play bark safety depths.
Calculate now →Play Bark Calculator
Work out how much certified play bark you need for a safe playground. Auto-sets BS EN 1177 depth by equipment fall height.
Calculate now →Planning & Water
Planting Calendar
Find the best months to sow, plant and harvest vegetables and flowers in the UK. Region-adjusted timings.
View calendar →Frost Date Calculator
Find your last frost and first frost dates by UK postcode or region. Growing season length and monthly frost risk.
Find my frost dates →Water Butt Calculator
Work out the right water butt size based on your roof area and local rainfall. Save money on your water bill.
Calculate now →Raised Bed Calculator
Calculate how much soil you need for a raised bed. Rectangular or L-shaped, with results in litres, bags and cost.
Calculate now →Home Improvement Calculators
Got a building project too? Our sister site HomeCalc.uk has free calculators for roofing, bricks, concrete, decking, fencing, rendering, radiators and heat pumps.
Browse home improvement calculators →How to Choose the Right Calculator
Every garden project starts with one question: how much do I actually need? Buying too little means a second trip to the garden centre. Buying too much means bags of topsoil sitting in the rain for months. Our calculators take the guesswork out of it.
If you are working on your lawn, start with the Grass Seed Calculator for new lawns or overseeding, or the Lawn Feed Calculator to get spring feeding right. For beds and borders, the Compost Calculator and Mulch Calculator handle volume-to-bag conversions so you know exactly what to order.
For hard landscaping — driveways, patios, paths — pick the material calculator that matches your project. The Gravel Calculator works in tonnes and bags, the Paving Calculator supports all standard UK slab sizes, and the Concrete Calculator covers everything from shed bases to fence posts. If your project needs a compacted foundation layer, run the Sub-Base Calculator first.
Not sure when to plant? The Planting Calendar shows sowing, planting and harvesting windows month by month. Pair it with the Frost Date Calculator to find your local last frost date before putting tender plants outside.
Our Methodology
Every calculator on GardenCalc is built specifically for UK gardens. We use metric measurements (metres, litres, kilograms), British product sizes (25-litre bags, bulk bags, standard turf rolls) and coverage rates based on UK industry guidance. Where relevant, we reference British Standards — the Play Bark and Bark Chippings calculators, for example, include BS EN 1177 safety depth requirements.
All calculators include a wastage allowance (typically 5-10%) because real gardens have curves, corners and uneven ground. We regularly update our data tables and pricing benchmarks so the results stay accurate season to season. If you spot anything that looks off, let us know — we take accuracy seriously.
GardenCalc is and always will be completely free to use. No account required, no hidden upsells. Just open a calculator, enter your numbers, and get the answer you need.
Stop Guessing. Start Growing.
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