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Planting Calculators

Seed Quantity Calculator

Seeds needed for a planting area, allowing for germination rate and thinning.

Enter values

Results update as you type.

Result

Seeds to sow

90

Packets to buy
1
Expected germinating
72
Plants wanted
60
Spare seeds
10
Thinning allowance
15 seeds
Seed cost
$2.50

About the Seed Quantity Calculator

Seeds needed for a planting area, allowing for germination rate and thinning.

Also known as: how many seeds do i need, seed packet calculator, sowing quantity, vegetable seed calculator.

How to use this calculator

  1. Enter plants wanted, germination rate, sow extra for thinning, seeds per packet and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

seeds = plants wanted ÷ germination rate × (1 + thinning)

Worked example

Using the values pre-filled in the calculator above:

  • Plants wanted = 60
  • Germination rate = 80 %
  • Sow extra for thinning = 20 %
  • Seeds per packet = 100
  • Price per packet = 2.5

the calculator returns:

  • Seeds to sow: 90
  • Packets to buy: 1
  • Expected germinating: 72
  • Plants wanted: 60