Seed Starting Calculator
How many seeds to sow to end up with the plants you want.
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How it works
Seeds to sow = plants wanted ÷ (germination rate × survival rate), rounded up. The germination rate is printed on most seed packets, and old seed usually germinates worse. Example: with the default values, 20 plants at 80% germination and 90% survival need 28 seeds.
FAQ
Is this calculator free?
Yes. No signup is needed and nothing you enter is stored.
Is the result exact?
Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.
Do my numbers leave my device?
No. The calculation runs in your browser.