Seed Rate Calculator
Select a crop to auto-fill typical seed weight and target population values
Enter seeds per pound from your seed lot, or switch to TKW (Thousand Kernel Weight in grams)
Desired final plant stand after germination and emergence losses
From the seed tag — the % of seeds expected to germinate under lab conditions
Additional % of viable seeds that fail to emerge above soil surface (typically 5–15%)
% of pure live seed in the lot — 100 minus any weed seed or inert material
Broadcast seeding requires ~17.5% more seed; precision drill uses no extra adjustment
Optional — enter to calculate total seed needed and seed cost
Optional — used to calculate seeds per row foot for planter calibration
Optional — enter seed price to calculate total field seed cost
Enter Your Planting Parameters
Select a crop, enter your target plant population and seed quality values, then see your required seeding rate in lbs/acre, kg/ha, and total seed needed.
How to Use the Seed Rate Calculator
Select Your Crop and Enter Seed Quality
Choose your crop from the dropdown to auto-fill typical seed weight and target population values. Then update the germination percentage from your seed tag and adjust the field emergence loss — typically 5–10% for good conditions, 10–15% for challenging early-season soils.
Enter Your Target Plant Population
Input the desired plant population in plants per acre. This is your agronomic target — the number of plants per acre you want established at the end of the growing season. Crop presets provide typical ranges; adjust for your variety, row spacing, and management goals.
Add Field Area and Row Spacing (Optional)
Enter your total field acreage to calculate how many pounds or kilograms of seed to purchase. If you plant in rows, enter your row spacing in inches to get seeds per row foot — the value used to calibrate your planter monitor or seed tube counter.
Review Results and Export
Your required seeding rate appears in lbs/acre, kg/ha, seeds/acre, and bu/acre (for applicable grain crops). The seed fate chart shows exactly where seed losses occur. Use Export CSV to save results for record-keeping, or Print Results for a field-ready copy.
Frequently Asked Questions
What is the difference between germination rate and emergence rate?
Germination rate, shown on the seed tag, is a laboratory measurement of what percentage of seeds begin the germination process under ideal temperature and moisture conditions. Emergence rate (or emergence percentage) is what happens in the field — the fraction of planted seeds that successfully establish above the soil surface as viable seedlings. Field emergence is always lower than laboratory germination because of soil temperature extremes, soil crusting, seed furrow closure problems, seed corn maggots, Pythium damping-off, and other real-world stresses. Our calculator separates these two values. The field emergence loss input represents the additional percentage loss beyond what the germination number already accounts for, so a 90% germination seed with 10% field emergence loss results in roughly 81% actual stand establishment.
What is Thousand Kernel Weight (TKW) and why use it instead of seeds per pound?
Thousand Kernel Weight is the mass in grams of exactly 1,000 seeds from a seed lot. It is used widely in metric countries and by pulse crop agronomists because it directly measures seed size variation between varieties and growing seasons. A large-seeded chickpea variety might have a TKW of 500g while a small-seeded type might be 250g — both are chickpeas but require very different seeding rates. TKW converts to seeds per pound using the formula: seeds/lb = 453,592 ÷ TKW. Measuring TKW from your actual seed lot is more accurate than using a variety average, since growing conditions affect kernel size. Our calculator accepts either input format and converts automatically.
How much does seeding method affect the required seeding rate?
Seeding method matters because different application methods achieve different levels of seed placement uniformity. Precision drilling places each seed at a consistent depth and spacing, achieving close to the theoretical stand — so no rate adjustment is needed. Standard drill seeding introduces some seed clustering and depth variability, requiring about a 5% rate increase. Broadcast seeding, whether aerial or ground-spread, results in the highest variability in seed placement, depth, and coverage, requiring a 15–20% rate increase (our calculator uses 17.5%). Transplanting — moving established seedlings into the field — also requires no extra seed adjustment. Note that broadcast seeding also results in less uniform stands and is generally used only for small seeds like canola, pasture grasses, or cover crops.
What seeds per row foot should I target for corn at 30-inch rows?
For corn planted in 30-inch rows targeting 32,000 plants per acre, the calculation is: seeds per row foot = target plants/acre × (row spacing in feet ÷ 43,560). At 30 inches, row spacing in feet = 30 ÷ 12 = 2.5 ft, so seeds per row foot = 32,000 × 2.5 ÷ 43,560 = approximately 1.84 seeds per foot of row. Most precision planters target between 1.5 and 2.5 seeds per row foot for corn, depending on target population and row spacing. For soybeans at 100,000 plants per acre in 15-inch rows, seeds per row foot would be around 2.87. Our calculator computes this automatically when you enter row spacing.
How do I use the reverse plant stand calculator?
Switch to the 'Achieved Plant Stand' mode using the tabs above the input card. Enter the seeding rate you actually applied (lbs/acre), your seed's germination percentage, the field emergence loss you observed or expect, and the seeds per pound for your seed lot. The calculator estimates how many plants per acre you should achieve as a result. This is useful after planting to predict whether a stand count will meet your minimum acceptable threshold before deciding whether to replant. It is also useful when evaluating historical records — for instance, if you know you planted 45 lbs/acre of wheat at 14,000 seeds/lb with 88% germination and 8% emergence loss, this mode tells you the expected stand.
What seeding rate should I use for canola?
Canola is one of the most challenging crops to calibrate because its tiny seeds — TKW typically 3–6 grams, with 80,000–150,000 seeds per pound — mean that small errors in seeder calibration translate to large population errors. Target populations for canola range from 1,000 to 1,700 plants per square metre (roughly 4,000,000 to 7,000,000 plants per acre). Typical seeding rates run from 3 to 7 lbs/acre (3.4 to 7.8 kg/ha) depending on seed size. Because canola is especially sensitive to seeding depth, soil temperature at planting, and seedbed moisture, emergence losses of 20–40% are common, meaning seeding rates must be increased substantially above the minimum theoretical rate. Use our calculator with a realistic emergence loss of 25–35% for canola to protect your stand.