Seed Quantity Calculator

Target Number of Plantsafter thinning

Seeds per Hole / Stationfor direct sow

Expected Germination Ratecheck seed packet

Succession Plantingshow many rounds?

Safety Buffer

Seeds to Buy

Total seeds needed—

Seeds per planting round—

Holes / stations—

Expected germination—

Related Calculators

How Many Seeds Do You Need?

The formula accounts for germination failure, thinning (where you plant 2–3 seeds per spot and remove extras), and a buffer for pest/weather losses.

The formula

Seeds needed = (Target plants × Seeds per hole × Safety buffer) ÷ Germination rate

Typical germination rates

Crop	Typical Rate	Viable Years
Tomatoes	75–90%	4–5 years
Peppers	55–80%	2–3 years
Carrots	55–75%	2–3 years
Lettuce	80–90%	2–3 years
Onions	70–80%	1–2 years
Beans	80–95%	3 years
Corn	75–90%	2–3 years
Parsnips	60–70%	1 year

Do a germination test: Before planting, place 10 seeds on a damp paper towel, fold it up, and put in a warm spot for 5–10 days. Count how many sprout — that's your germination rate.