Gardening & Plants Calculators
Plan and grow a better garden, work out plant spacing and seed counts, fill a raised bed, dial in fertilizer and watering, time your planting to the last frost, and balance a compost pile. Every tool uses exact maths or a sourced horticulture guideline and runs entirely in your browser.
- Plant Spacing Calculator Enter your bed size and plant spacing to see how many plants fit, in a square grid or a space-saving triangular layout.
- Seed & Row Spacing Calculator Enter your row length and seed spacing to get the number of seeds per row, and for a whole bed if you add the bed width and row spacing.
- Raised Bed Soil Calculator Enter your raised bed's length, width and depth to get the volume of soil to buy, in litres, cubic feet and yards, and the number of bags.
- Fertilizer Calculator (Nitrogen Rate) Enter your target nitrogen rate, your area and the fertilizer's %N, and get how much product to apply.
- Garden Watering Calculator Enter your bed size and the depth of water you want to apply, and get the volume in litres and gallons.
- Planting Date Calculator (from Last Frost) Pick a vegetable and enter your average last spring frost date to get the dates to start seeds indoors, transplant and direct-sow.
- Grow Light DLI Calculator Enter your grow light's intensity
- Compost Ratio Calculator (C:N) Add the materials in your compost pile and their proportions, and see the blended carbon-to-nitrogen ratio, with guidance to balance it.
- Growing Degree Days (GDD) Calculator Enter the daily high and low and a base temperature to get the growing degree days, and multiply by the number of similar days for an accumulated total.
- Pond Volume & Liner Calculator Enter the length, width and average depth to get the pond volume in litres and gallons, and the liner dimensions to buy.
- Spray & Pesticide Mix Calculator Enter your sprayer volume and the product's label rate to get how much concentrate to add.
Frequently asked questions
Are these gardening calculators accurate?
The maths is exact, plant-spacing geometry, fertilizer nitrogen rates, watering volumes and the DLI equation. The reference data (compost C:N ratios, frost-relative planting offsets, light targets) is from extension-service and horticulture sources cited on each tool page, and is presented as general guidance that varies by region and variety.
Do they work in metric and imperial?
Yes, beds, spacing and water toggle between metres/centimetres and feet/inches, and results show litres and gallons, cubic metres and cubic yards.
Do I need my local frost date?
For the planting-date calculator, yes, enter your average last spring frost date (from a regional extension service or frost-date lookup) and it works out the sowing and transplant dates. The other tools need no location data.
Is my data uploaded?
No. Every tool runs entirely in your browser, nothing is sent to a server, and they work offline.