Lawn & Garden calculators
Lawn and garden quantities with the rate shown beside the answer — seeding rates by grass type, fertilizer worked back from the nitrogen number on the bag, and plant spacing for both square and staggered layouts.
Lawn
- Grass Seed CalculatorPick your grass type and the calculator uses its actual seeding rate. Overseeding an existing lawn takes roughly
- Sod CalculatorSod is sold in several different piece sizes depending on where you are. Pick the one your supplier uses.
- Fertilizer CalculatorEnter the first number from the bag and the nitrogen rate you want. This works backwards to the pounds of produc
- Lawn Area CalculatorReal lawns are not rectangles. Break yours into shapes, add them up, and subtract what is not grass.
Planting
- Plant Spacing CalculatorEnter the bed size and spacing. This gives both layouts, because staggered planting fits about 15% more plants i
- Raised Bed Soil CalculatorEnter the bed size and pick a mix. This splits the total into the components you actually have to buy.
- Garden Soil CalculatorFor in-ground beds and borders. The settlement allowance covers screened soil consolidating once it is spread an
- Compost CalculatorCompost goes on far thinner than mulch. A quarter-inch lawn topdressing is a different order of magnitude from a
Cleanup
Reference
- Grass Seed Rate ChartEvery common lawn grass, its seeding rate new and overseeded, and when to sow it.
- Fertilizer Rate ChartHow many pounds of product to spread for 1 lb of actual nitrogen, for every common bag analysis.
- Plant Spacing ChartPlants per 100 square feet at every common spacing, both layouts, plus what spacing to use for what.
Why the rate is shown beside the answer
Every calculator here prints the rate, spacing or analysis it used, and the arithmetic that got from your measurements to the quantity. That is deliberate, because a garden quantity is only as good as the rate behind it and those rates vary enormously — tall fescue seeds at 9 lb per 1,000 ft² and Kentucky bluegrass at 2, a four-fold difference that a single "grass seed calculator" figure cannot capture.
The fertilizer page is the clearest case. Lawn feed is applied by nitrogen, not by product, so the pounds you spread depend on the first number on the bag: 4.17 lb of a 24-0-4 delivers the same nitrogen as 10 lb of a 10-10-10. Spreading the second figure of the first product would put down two and a half times the intended nitrogen and burn the lawn.
A correction to the previous version of this site
The earlier single-page version of these calculators, at gardenerscalculator.netlify.app, had a unit-conversion fault that made every area-based answer roughly 10.8 times too low. It converted the lawn area to square metres while leaving the bag coverage, plant spacing and application rate in imperial units, so a 600 ft² lawn needing 60 rolls of sod was told to buy 6, and a 10,000 ft² lawn needing 10 bags of seed was told to buy 1.
That is fixed. The arithmetic now runs entirely in one unit system with conversion at the input boundary only, and the test suite checks each of those four specific cases along with 60 others. If you used this site before September 2026 for sod, seed, fertilizer or plant counts, the numbers were wrong and these are right.
What these are not
Quantities for planning and buying. Not agronomic advice, not a soil test, and not a substitute for the label on the product you actually buy — rates vary by variety and formulation, and the bag is the authority.