Home & DIY Calculators
Plan a project before you buy. These calculators turn the size of your space into the amount of material you need, from gravel and mulch to deck stain, air conditioner capacity, wire size and generator watts. Each one shows its formula, a worked example and the mistakes that cost people money, so you order the right amount the first time.
Tons and cubic yards for paths and drivewaysMulch Calculator
Cubic yards and bags of mulch for bedsDeck Stain Calculator
Gallons of stain for any deckBTU Calculator
Air conditioner size for any roomWire Gauge Calculator
Copper AWG by amps, distance and voltage dropGenerator Size Calculator
Watts needed with surge and headroom
Which Home & DIY calculator do I need?
| Calculator | Question it answers | What you enter | What you get |
|---|---|---|---|
| Gravel | How much gravel for a path, patio base or driveway? | Area shape and size, depth, material | Cubic yards, tons, bags and cost |
| Mulch | How much mulch for a garden bed or tree ring? | Bed shape and size, depth, bag size | Cubic yards, bags and cost |
| Deck stain | How many gallons of stain or sealer? | Deck, railing and stairs, coats, coverage | Gallons to buy, including waste |
| BTU | What size air conditioner for a room? | Room size, ceiling height, sun, people | BTU per hour, tons and unit size |
| Wire gauge | What wire size for this load and distance? | Amps, voltage, length, copper or aluminum | AWG size and voltage drop |
| Generator size | How many watts do I need? | Appliance running and starting watts | Generator watts, kVA and amps |
How to measure before you calculate
- Sketch the area. Draw it on paper and split odd shapes into rectangles, circles and triangles. Calculate each one and add them up.
- Measure depth after settling. Gravel, mulch and soil compact over time, so plan for the final depth you want.
- Measure twice. A small error in length or width becomes a large error in volume once you multiply by depth.
- Check the label. Coverage, density and wattage printed on the product beat any general figure.
Why your estimate may differ from what you buy
A calculator gives the amount your measurements need. Real jobs add waste, uneven ground, moisture in the material and supplier minimums. Bulk materials are often sold by the cubic yard or the ton, bags come in different sizes, and paint and stain cans are sold in set volumes. Round up to the next available size and keep a small allowance for waste and mistakes.
Units that cause mistakes
- A cubic yard is 27 cubic feet, a cube 3 feet on each side.
- A short ton is 2,000 pounds. A metric ton is 1,000 kilograms, about 2,205 pounds.
- Cubic yards measure volume and tons measure weight, so the same cubic yard of different materials weighs different amounts.
- Depth is usually measured in inches while length and width are in feet. Convert depth by dividing by 12.
Safety and the limits of an estimate
The electrical tools, wire gauge and generator size, follow published standards such as the NEC ampacity tables, but they cannot see your local code, conduit, temperature or equipment ratings. Have a licensed electrician check any installation. Never run a generator indoors or in a garage, because it produces carbon monoxide.
Frequently asked questions
How much extra material should I order?
Many projects add a small allowance for waste and settling. Base layers that are compacted, such as under a driveway, often need more. Ask your supplier what they recommend for your product.
What is the difference between tons and cubic yards?
A ton is a weight and a cubic yard is a volume. To convert, you need the density of the material, which is why the gravel calculator lets you choose or enter one.
Can I use these calculators for commercial jobs?
They are good for planning, but large or regulated jobs should be checked against the plans, local codes and a professional estimate.