liminfoSeed Rate Calculator
Free web tool: Seed Rate Calculator
Seeding Rate
2.88 lbs/acre
Total Seed Needed
287.9 lbs
Seeds per acre
37,427
Seeds needed = Target Population / (Germination Rate {'\u00D7'} Survival Rate). Seeding Rate = Seeds needed / Seeds per weight unit.
About Seed Rate Calculator
The Seed Rate Calculator helps farmers, agronomists, and gardeners determine how much seed to plant per unit area to achieve a target plant population. You input the field area (in acres or hectares), seeds per pound or kilogram of the seed variety, the desired plant population density per area unit, germination rate (%), and survival rate (%). The tool then calculates the adjusted seeding rate in weight per area, the total seed weight needed for the entire field, and the actual seeds per area required to hit your population target.
The core formula adjusts for seed quality losses: Seeds Needed Per Area = Target Population ÷ (Germination Rate × Survival Rate). This accounts for seeds that fail to germinate and seedlings that die before establishment. For example, to achieve 32,000 plants per acre with 95% germination and 90% survival, you need approximately 37,427 seeds per acre — significantly more than your target population.
This calculator supports both imperial (acres, pounds) and metric (hectares, kilograms) units. It is applicable to a wide range of crops including corn, soybeans, wheat, cotton, canola, sorghum, and cover crops. Agronomists use seed rate calculations as a fundamental step in crop planning, as proper stand establishment directly affects yield potential and input efficiency.
Key Features
- Calculates seeding rate in lbs or kg per acre or hectare
- Adjusts for germination rate to account for non-germinating seeds
- Adjusts for survival rate to account for seedling mortality before establishment
- Computes total seed weight needed for the entire field area
- Shows seeds per area unit required to hit population target
- Supports both imperial (acres, lbs) and metric (hectares, kg) unit systems
- Input seeds per pound or per kilogram to match your seed bag specifications
- Formula: Seeds Needed = Target Population ÷ (Germination Rate × Survival Rate)
Frequently Asked Questions
What is a seeding rate and why does it matter?
Seeding rate is the amount of seed planted per unit area, expressed in weight (e.g., lbs/acre or kg/ha). It matters because planting too little seed results in thin stands with low yield potential, while planting too much wastes expensive seed and can cause over-competition. Optimal seeding rates maximize both stand establishment and economic return.
How does germination rate affect the seed calculation?
Germination rate is the percentage of seeds that will sprout under ideal conditions, usually printed on the seed bag label. If your germination rate is 95%, only 95 out of 100 seeds will germinate. The calculator divides the target population by the germination rate to compensate for non-germinating seeds.
What is survival rate and how is it different from germination rate?
Survival rate accounts for seedlings that germinate but die before they are counted as established plants — due to soil crusting, pest damage, disease, or drought stress. Germination rate applies at the seed stage, survival rate applies after germination. Both reduce the effective stand from the seeds planted.
How do I find the seeds per pound or kg for my crop?
Seeds per unit weight is typically printed on the seed bag or available from the seed supplier. It varies widely by crop and variety: corn averages about 1,400–1,600 seeds/lb, soybeans about 2,800 seeds/lb, wheat about 13,000–16,000 seeds/lb, and canola about 150,000–200,000 seeds/kg.
What target plant population should I use for corn or soybeans?
Target populations vary by crop, region, and soil type. Common targets are 32,000–34,000 plants per acre for corn in high-yield environments, and 100,000–140,000 plants per acre for soybeans. Consult your local extension service or seed company agronomist for regionally appropriate recommendations.
Can I use this calculator for small garden plots?
Yes. You can enter small area values like 0.01 acres (about 436 sq ft) or 0.001 hectares. The calculator scales linearly, so seeding rate per unit area remains constant regardless of field size. Just make sure to match your weight units (lb or kg) with your seed bag specifications.
What if my germination rate and survival rate together reduce effective stand too much?
If (germination × survival) is low — say 0.90 × 0.80 = 0.72 — you need to plant 39% more seeds than your target population. The calculator computes this automatically. In practice, if effective stand efficiency is below 70%, consider using higher-quality seed or improving field conditions before planting.
How does the total seed weight calculation work?
Total seed weight = (Seeds Per Area Required) ÷ (Seeds Per Weight Unit) × Field Area. The seeds per area required is already adjusted for germination and survival. Dividing by seeds per unit weight converts seed count to weight, then multiplying by field area gives the total weight needed for the entire field.