About this calculator
The Seed Rate Calculator is a practical tool that is meant to assist farmers, agronomists, and researchers in the determination of the required number of seeds that should be used during planting.
How to Use the Calculator
Using the calculator is simple and straightforward:
- Enter the target plant population (plants per square meter).
- Input the thousand grain weight (TGW), usually available from seed packaging or lab measurements.
- Provide the germination percentage (as indicated on seed labels or from a germination test).
- Estimate expected field losses (due to pests, soil conditions, or mechanical issues).
- Enter the area to be planted (in hectares).
Once these values are entered, the calculator instantly provides:
- The sowing rate in kilograms per hectare (kg/ha).
- The total seed tonnage required for the specified area.
- The number of seeds sown per square meter.
- The total number of seeds per hectare and overall.
- The adjusted effective germination percentage after field losses.
Example: Suppose you want to plant wheat with these values; Target plant population: 250 plants/m²,TGW: 45 g,Germination: 90%,Field Losses: 10%,Area: 5 hectares. The calculator would output: Sowing rate: ~138.89 kg/ha,Seed tonnage needed: ~0.63 tonnes,Seeds sown: ~308 seeds/m², Seeds per hectare: ~3,080,000, Total seeds needed: ~15.4 million, Effective germination: ~81%
Is higher seeding always better?
a higher seed rate would insure against low germination or losses in the field, but has its own actual disadvantages. Excessive numbers in the plants will fight over the light, water, and nutrients; this may lead to slender stems, increase the disease, lodging (crop falling over), decrease in the quality of grain and in most cases there is no direct increase or even a decrease in final yield per hectare. It also causes seed cost to go up and may compel you to add more fertiliser and crop-protection.
Do all crops use the same seed rate formula?
Though the same basic math is used in the majority of seed rate calculations, not all crops apply the same formula in practice. This shared calculation changes considerably by the parameters, adjustments and practical choices, based on crop biology, sowing technique and objectives of production.