28 gardening tools, grouped by task
Gardens are mostly a question of volume and spacing: how much soil fills a bed, how many plants fill a run, how much water a roof will actually collect. These sections group the calculations by the job in hand rather than by season.
Every calculator in this section now carries a full explanation: what it works out, the method, a worked example, the mistakes people make, and where the honest answer is fewer plants, less material or a different approach entirely. Where the law applies — nesting birds, protected trees, invasive aquatic plants, permeable surfacing — the page says so.
Start here
If you are not sure where to begin, these tools answer the questions readers ask most often in this section.
Soil, compost and mulch 6 tools
Bulk volumes for beds, borders and bins, where ordering short is the usual mistake.
Planting, spacing and lawns 6 tools
How many plants a space will take at a sensible mature spacing, and how much seed or feed a lawn needs.
Water, ponds and rainwater 5 tools
Liner sizes, pump flow, stocking and the amount of rain a roof will realistically collect.
Hard landscaping and surfaces 3 tools
Loose materials and surface treatments for paths, drives and decking.
Light, heat and power 3 tools
Aspect, frost protection and the running cost of outdoor lighting.
Waste and plant problems 3 tools
Sizing the clear-up after a big cut back, and working out what is damaging a plant.
Common questions
How accurate are the soil and compost volumes?
The geometry is exact — a bed 2 m by 1 m filled to 300 mm needs 0.6 cubic metres. The uncertainty is in the material, not the maths. Bagged compost is sold by volume but settles by roughly 10–20% once watered and trodden, and topsoil delivered loose bulks up compared with the same soil in the ground. Order a little over rather than exactly.
Should I use bags or a bulk bag?
Compare on volume rather than price per bag. A standard bulk bag holds somewhere near 0.7–0.9 cubic metres depending on the supplier, which is usually far cheaper per litre than sacks once you need more than about ten of them. The calculators give you a cubic-metre figure precisely so the comparison is straightforward.
Why do plant spacing tools give fewer plants than I expected?
Because they space for the mature size rather than the size in the pot. Close planting looks better in the first season and worse in every season after, as plants compete for light, water and airflow. Where you genuinely want quick cover — a hedge, for instance — the spacing figure is editable so you can plant tighter with your eyes open.
Do the rainwater figures account for losses?
Yes, at a simplified level. Not all rain that lands on a roof reaches the butt: some evaporates, some is lost to initial wetting of the surface and some overflows during heavy downpours. The tool applies a collection efficiency you can adjust, and the default is deliberately conservative.
Are these tools written for the UK climate?
Mostly. Rainfall, frost protection, growing seasons and lawn feeding rates assume UK conditions. The underlying arithmetic works anywhere, but you would need to substitute local rainfall and temperature figures for the results to mean much elsewhere.
Is anything I enter saved?
No. Every garden calculator runs entirely in your browser and nothing you type is transmitted or retained as a calculator record.
Related subjects
Questions rarely sit inside a single subject. These sections cover the calculations most often needed alongside garden planning.