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Seed Rate Calculator

Seeding rate (kg/ha) from population, seed weight, germination & purity.

Introduction

Seed Rate Calculator — Seeding rate (kg/ha) from population, seed weight, germination & purity. Enter Desired plants per m², 1000-seed weight (g), Germination (%), Purity (%) to get an instant, accurate result.

Formula

Seed rate (kg/ha) = (desired plants/m² × 1000-seed weight in grams) / (100 × germination% × purity%). This is the standard agronomic seeding-rate formula used by extension services.

Step-by-step

  1. Enter the Desired plants per m².
  2. Enter the 1000-seed weight (g).
  3. Enter the Germination (%).
  4. Enter the Purity (%).
  5. Click Calculate to see your result instantly.

Real-world example

Example: With Desired plants per m² = 20, 1000-seed weight (g) = 30, Germination (%) = 90, Purity (%) = 98, the Seed Rate Calculator gives Seed Rate Kg Ha: 6.8027.

Frequently Asked Questions

Why do germination and purity reduce the seed rate?
They increase it, not reduce it — dividing by germination and purity fractions accounts for seeds that will not sprout or are inert material, so more seed must be sown to reach the target plant stand.
Where do I find 1000-seed weight?
It is usually printed on the seed bag tag or seed test certificate; it varies noticeably by crop and even by seed lot.
What inputs does the Seed Rate Calculator need?
You'll need to provide: Desired plants per m², 1000-seed weight (g), Germination (%), Purity (%). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Seed Rate Calculator?
The Seed Rate Calculator applies the formula exactly as calculated — Seed rate (kg/ha) = (desired plants/m² × 1000-seed weight in grams) / (100 × germination% × purity%). This is the standard agronomic seeding-rate formula used by extension services. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Seed Rate Calculator free to use?
Yes, the Seed Rate Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Seed Rate Calculator

The Seed Rate Calculator uses a real, verifiable formula — Seed rate (kg/ha) = (desired plants/m² × 1000-seed weight in grams) / (100 × germination% × purity%). This is the standard agronomic seeding-rate formula used by extension services. — so results are accurate every time, not an approximation.