Gardening Calculators

Healthy plants start with the right soil chemistry and organic matter balance. Too little fertilizer and growth stalls; too much and you burn roots or create nutrient runoff. The same goes for compost — the right carbon-to-nitrogen ratio determines whether your pile breaks down in weeks or sits inert for months. These calculators take the guesswork out of both.

What these tools cover

The compost calculator estimates how much finished compost you need to amend a garden bed to a target depth, and how much raw material (browns and greens) to combine to hit the ideal 25–30:1 carbon-to-nitrogen ratio. It covers raised beds, in-ground beds, and top-dressing applications. The fertilizer calculator works from your soil test results and target nutrient levels to tell you exactly how much of a given fertilizer product to apply per square foot or per acre — preventing both under- and over-application.

Getting the best results

For fertilizer calculations, a soil test from your local cooperative extension office is the most reliable input. Without one, you're estimating your starting point. For compost, weigh your materials rather than estimating by volume — density varies widely between straw, wood chips, kitchen scraps, and grass clippings.

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