Seed Germination Rate Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026Seed Germination Rate Calculator
Testing germination rate on a small sample batch before planting your entire seed supply is a common and worthwhile practice - it tells you exactly how many extra seeds to sow to reliably hit a target number of successful plants.
Germination Rate% = (Seeds Germinated / Seeds Planted) x 100
Example
17 seeds germinated out of 20 test seeds planted:
Germination Rate = (17 / 20) x 100 = 85.0% (good germination rate)
Reading Your Rate
| Germination Rate | Assessment |
|---|---|
| 90%+ | Excellent - fresh, high-quality seed |
| 70-89% | Good germination rate |
| 50-69% | Moderate - consider fresher seed or improved conditions |
| Below 50% | Poor - seed may be old or conditions unfavorable |
Why Seed Age Matters
Seed viability naturally declines over time, and improper storage (particularly exposure to heat and humidity) accelerates this decline significantly - this is exactly why older saved or leftover seed typically tests at a lower germination rate than fresh seed of the same variety, and why a quick germination test before a full planting session can save you from a disappointing, sparsely-filled garden bed.