Soil Amendment Calculator — Improve Your Garden Soil
Calculate quantities of grit, sand, or organic matter to improve your soil.
Percentage of amendment in total mix
How We Calculate This
This calculator works out how much amendment material you need based on the area, working depth, and desired mix ratio.
Formula: Amendment Volume = Area × Depth × (Mix Ratio / 100)
Weight is calculated using typical densities: grit ~1,600 kg/m³, sand ~1,500 kg/m³, perlite ~100 kg/m³, compost ~500 kg/m³.
Frequently Asked Questions
Related Calculators
Raised Bed Soil Calculator
Calculate how much soil you need to fill a raised bed of any size.
Compost Bin Size Calculator
Work out the ideal compost bin size for your garden waste output.
Topsoil Calculator
Calculate topsoil volume needed in cubic metres, bulk bags, or tonnes.
Mulch Calculator
Work out how much mulch you need for beds, borders, and paths.
Potting Mix Calculator
Work out the right ratios of compost, perlite, and vermiculite for potting mix.
Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.