Backyard calculators that show their working
Soil, seed, sod, pool chemicals and holiday turkey timings, worked out in seconds. Every tool explains the formula and links its sources, so you can trust the answer.
- Raised Bed Soil Calculator
- Seed Starting Calculator
- Mulch, Compost & Topsoil Calculator
- Plant Spacing Calculator
- Compost C:N Ratio Calculator
- Rain Barrel Calculator
- Grow Light DLI Calculator
- Lawn Fertilizer Calculator
- Grass Seed Calculator
- Sod Calculator
- Sprinkler Run Time Calculator
- Pool Volume Calculator
- Pool Chlorine Calculator
- Hot Tub Chlorine & Bromine Calculator
- Pool Salt Calculator
- Pool Drain & Refill Calculator
- Turkey Thawing & Cooking Time Calculator
- Meat Per Person Calculator
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- 18 free calculators
- Formulas and sources shown
- US and metric units
- Runs in your browser
In season now
Handy tools for this time of year.
- Raised Bed Soil CalculatorSoil, compost and mix amounts for one or many beds, in bags or bulk.
- Seed Starting CalculatorWhen to sow indoors, direct sow and transplant, counted from your last frost date.
- Mulch, Compost & Topsoil CalculatorCubic yards, cubic feet, litres and bags for any area and depth.
- Plant Spacing CalculatorHow many plants fit a bed or area, in a square or staggered grid.
- Compost C:N Ratio CalculatorBalance greens and browns for a compost pile that heats up and doesn’t smell.
- Rain Barrel CalculatorHow much rainwater your roof collects and how many barrels or water butts to fill.
- Grow Light DLI CalculatorDaily light integral from PPFD and hours, or the PPFD a plant needs.
- Lawn Fertilizer CalculatorHow much product to spread for a target amount of nitrogen.
- Grass Seed CalculatorSeed needed for a new lawn or overseeding, by grass type and area.
- Sod CalculatorSquare feet, rolls or slabs and pallets of sod or turf for any lawn shape.
- Sprinkler Run Time CalculatorMeasure your sprinkler with a can test and see how long to water each week.
- Pool Volume CalculatorGallons or litres in rectangular, round, oval and kidney pools, including sloped floors.
- Pool Chlorine CalculatorHow much liquid chlorine, bleach or granules raises free chlorine, and the level to aim for.
- Hot Tub Chlorine & Bromine CalculatorSmall-volume doses in grams, ounces and millilitres for spas and hot tubs.
- Pool Salt CalculatorBags of salt to bring a saltwater pool up to its target level.
- Pool Drain & Refill CalculatorHow much water to replace to lower stabilizer (CYA), calcium hardness, salt or TDS.
- Turkey Thawing & Cooking Time CalculatorWhen to start thawing and when it goes in the oven, worked back from your dinner time.
- Meat Per Person CalculatorHow much raw brisket, pulled pork, chicken, turkey, ham, burgers or hot dogs to buy for a party or cookout.
- Raised Bed Soil CalculatorSoil, compost and mix amounts for one or many beds, in bags or bulk.
- Seed Starting CalculatorWhen to sow indoors, direct sow and transplant, counted from your last frost date.
- Mulch, Compost & Topsoil CalculatorCubic yards, cubic feet, litres and bags for any area and depth.
- Plant Spacing CalculatorHow many plants fit a bed or area, in a square or staggered grid.
- Compost C:N Ratio CalculatorBalance greens and browns for a compost pile that heats up and doesn’t smell.
- Rain Barrel CalculatorHow much rainwater your roof collects and how many barrels or water butts to fill.
- Grow Light DLI CalculatorDaily light integral from PPFD and hours, or the PPFD a plant needs.
- Lawn Fertilizer CalculatorHow much product to spread for a target amount of nitrogen.
- Grass Seed CalculatorSeed needed for a new lawn or overseeding, by grass type and area.
- Sod CalculatorSquare feet, rolls or slabs and pallets of sod or turf for any lawn shape.
- Sprinkler Run Time CalculatorMeasure your sprinkler with a can test and see how long to water each week.
Pool & hot tub
Pool volume, chlorine, salt, water replacement and hot tub chemical amounts.
- Pool Volume CalculatorGallons or litres in rectangular, round, oval and kidney pools, including sloped floors.
- Pool Chlorine CalculatorHow much liquid chlorine, bleach or granules raises free chlorine, and the level to aim for.
- Hot Tub Chlorine & Bromine CalculatorSmall-volume doses in grams, ounces and millilitres for spas and hot tubs.
- Pool Salt CalculatorBags of salt to bring a saltwater pool up to its target level.
- Pool Drain & Refill CalculatorHow much water to replace to lower stabilizer (CYA), calcium hardness, salt or TDS.
BBQ & holiday cooking
Turkey and party planners: thawing, cooking times and how much meat to buy.