DIY projects blow their budgets in the materials aisle, not the tool aisle. Order too little and you lose a weekend to a second trip; order too much and you are storing bags of cement for a decade. These calculators turn your measurements into order quantities — including the waste allowance and bag sizes that catch people out.
They are organised by project, not by formula: tiling and flooring, bulk materials for the yard, lawn and garden, paint and paper, and the electrical jobs in the garage. Measure the space, pick the matching tool below, and shop with a number you can defend.
Which DIY calculator do you need?
Tiling a floor or shower? Start with the tile calculator for tile and box counts, then the grout calculator for the grout those joints will take. Pouring or spreading bulk material — the concrete calculator, gravel calculator and cubic yard calculator convert your dimensions into yards, tons and bags. For the garden, the mulch calculator, topsoil calculator and grass seed calculator cover beds and lawns. Decorating? The paint calculator subtracts doors and windows properly. And for wiring and power, use the LED resistor calculator, battery runtime calculator and generator size calculator.
Concrete, Gravel & Bulk Materials
Yards, tons and bags for pours, driveways, paths and beds — the heavy materials where guessing costs real money.
Gravel Calculator
How much gravel your driveway or path really needs.
Concrete Calculator
Cubic yards and bags for slabs, walls & footings.
Cubic Yard Calculator
Cubic yards, tons, bags & cost for mulch, gravel, soil & concrete.
Lawn & Garden
Seed, mulch, topsoil and planting dates — quantities for the green side of the fence, worked out from your bed sizes and frost dates.
Grass Seed Calculator
Pounds of seed for new lawns & overseeding, by grass type.
Mulch Calculator
How many bags or cubic yards of mulch your garden beds need.
Topsoil Calculator
Cubic yards and bags of topsoil for beds & lawns.
Seed Starting Calculator
When to start seeds indoors from your last frost date.
Tile, Paint & Wall Finishes
Tiles, grout, paint and wallpaper for the room you are redoing — with waste allowances and openings subtracted.
Tile Calculator
How many tiles (and boxes) your floor, shower, or wall really needs.
Grout Calculator
How much grout you need — lbs, kg and bag count.
Paint Calculator
How many gallons your room really needs — doors & windows subtracted.
Wallpaper Calculator
How many rolls you need — pattern repeat handled.
Electrical & Power
Resistor values for LEDs, how long a battery will run a load, and what size generator your essentials actually need.
LED Resistor Calculator
The right resistor for any LED — value, wattage, E12.
Battery Runtime Calculator
How long will your battery last? RV, solar & camping.
Generator Size Calculator
What size generator runs your house? Tick appliances, get watts.