Garden & Groundworks Calculators
Free UK calculators for common garden and groundworks projects — sharp sand for patios, artificial grass sub base, fence panels and soakaway drainage crates.
Sharp Sand Calculator
Calculate sharp sand in tonnes, kg and bags for patios, paving slabs, artificial grass and screeding.
Artificial Grass Sub Base Calculator
Calculate MOT Type 1, sharp sand, grano dust, weed membrane and pins for an artificial grass base.
Fence Panel Calculator
Calculate how many fence panels, posts, gravel boards and Postcrete bags you need for a garden fence.
Soakaway Crate Calculator
Estimate the number of soakaway crates needed for patios, driveways and garden drainage projects.
Planning a garden groundworks project
Most garden hard landscaping projects follow a similar sequence: excavate, install a compacted sub-base, add a laying course, then finish with slabs, artificial grass or gravel. Getting the material quantities right before you order saves costly return deliveries.
For artificial grass installations, the standard build-up is 75–100mm of compacted MOT Type 1 sub-base, a permeable weed membrane, then 20–25mm of sharp sand or grano dust as the laying course. Use the Artificial Grass Sub Base Calculator to calculate all materials in one go.
For garden fencing, measure the total run, divide by your panel width (typically 1.83m for standard 6ft panels), then add one post per panel plus one. The Fence Panel Calculator also works out gravel boards and Postcrete bags automatically.
For drainage projects, the Soakaway Crate Calculator estimates the number of polypropylene crates needed based on your drainage area, rainfall design event and soil type. Always consult a drainage professional for regulated or high-risk sites.