Buy enough seed without guessing.

Turn bed dimensions and final plant spacing into a seed allowance, then adjust for germination and packet size.

Crop presetBed length (m)Bed width (m)Final spacing (cm)Expected germination (%)Extra seed buffer (%)Seeds per packet

PLANTING POSITIONS80020 rows × 40 positions

SEEDS TO ALLOW103685% germination + 10% buffer

PACKETS TO BUY3at 500 seeds / packet

FORMULApositions ÷ germination rate × safety buffer

This estimates seed allowance from final plant spacing. Tiny seeds that are broadcast or sown thickly and later thinned can need a different sowing density. Seed packet counts vary by supplier, so enter the packet quantity you are actually considering.

HOW IT WORKS

Start from the plants you want to finish with.

The calculator first estimates planting positions from bed length, width and spacing. It then allows extra seed for less-than-perfect germination and an optional safety buffer before converting the total into packet quantities.

It is best suited to crops planted at known final spacing. Broadcast sowing, dense baby-leaf production and crops routinely oversown then thinned can use much more seed than a final-spacing model suggests.