Garden calculators
& useful tools.
Measure what you have. Explore what might work. Each tool has its own instructions, examples and a clear explanation of what the result can tell you.
Design a border that has room to grow.
Three planting directions, a scaled plan, mature footprints and a flowering calendar. Swap plants, move them into place, then print your planting list.
Open the garden border planner ↗Plant spacing calculator
Estimate plant numbers from bed length, width and spacing. Use metric or imperial measurements and see what the square-grid estimate leaves out.
Open toolRaised bed soil calculator
Calculate raised-bed fill in litres and cubic metres, plus the number of soil bags. Enter inside dimensions and the depth you intend to fill.
Open toolRainwater harvesting calculator
Estimate rainwater from a connected roof area and rainfall event. Compare collection losses, tank space, water stored and overflow in litres.
Open toolAquarium water change calculator
Model nitrate dilution through repeated partial water changes. Include nitrate in replacement water and compare concentrations over six changes.
Open toolSeed starting calculator
Work backwards from your planned planting date to sowing and hardening dates. Use your local freeze reference and the growing interval on the seed packet.
Open toolHydrangea pruning tool
Choose an identified hydrangea group to find its pruning approach. Compare old wood, new wood, reblooming and climbing types before cutting.
Open toolGreenhouse temperature log
Record greenhouse and outdoor overnight minima, chart your readings and export CSV. A free temperature log saved in your browser, with no account.
Open toolPut the calculation in context.
Tools work best alongside the garden, plant or aquarium you are actually planning. Follow the related guide on each page for the choices the inputs cannot make for you. Everything runs in your browser without an account; the temperature log can save your own readings locally and export them as CSV.
Explore the guides →