Seed Rate & Plant Population Calculator
Enter your field size and spacing to find out how many plants your field will hold and how much seed to buy, adjusted for germination losses.
Seed rate calculator form
YOUR SEED & PLANT ESTIMATE
Breakdown
- Based on your row and plant spacing across the whole field.
- Total seeds needed already includes extra seed for expected germination losses.
Assumptions: This estimate assumes uniform spacing and 100% field usability. Actual seed needs vary with soil type, planting method, seed quality and local recommendations — confirm with your local agricultural extension officer where possible.
How this calculator works
The calculator first works out your plot’s area, then figures out how many plants fit into that area based on your row and plant spacing, then converts that plant count into a seed weight using your germination rate and 1000-seed weight.
Worked example
Example only — not a universal recommendation.
A 2-hectare maize field, planted at 75 cm between rows and 25 cm between plants, with 90% germination and a 1000-seed weight of 300 g:
Plants per m² = 10,000 ÷ (75 × 25) = 5.3 | Field area = 20,000 m² | Plant population ≈ 106,700 plants
Total seeds needed = 106,700 ÷ 0.90 ≈ 118,600 seeds | Seed required ≈ 35.6 kg (about 17.8 kg/ha)
Frequently asked questions
What is 1000-seed weight and where do I find it?
It’s the weight, in grams, of 1,000 seeds of that variety — a standard way seed companies describe seed size. It’s usually printed on the seed bag label; if not, ask your seed supplier.
Why does the calculator ask for germination rate?
Not every seed sown will emerge as a plant. Buying only enough seed for your exact target population, with no allowance for germination failure, usually leaves your field under-planted.
Can I use this for any crop?
Yes — the formula works for any crop planted in rows. Just enter the spacing and seed details for your specific crop and variety.
Does this tool store my data?
No. All calculations happen in your browser. Nothing you enter is sent anywhere or saved.