Seeding Rate Calculator
Select a crop to auto-fill typical seed weight and target population
Equivalent: 141.7 g TKW
Desired final plant stand (plants per acre)
From seed tag. Lab germination under ideal conditions.
Additional % of viable seeds that fail to emerge in field. Typically 5–15%. Emergence loss is added on top of germination loss.
Used to calculate seeds per row foot for planter calibration
Enter Your Seed and Field Data
Select a crop type, enter your target plant population, seed weight, and germination rate to calculate your optimal seeding rate in lbs/acre, kg/ha, seeds/acre, and more.
How to Use This Calculator
Select Your Crop and Unit System
Choose your crop from the dropdown to auto-fill typical seed weight (TKW or seeds per pound) and target plant population. Select Imperial (lbs/acre) or Metric (kg/ha) depending on how your seed is sold and how you manage records. You can switch seed weight entry between seeds per pound and Thousand Kernel Weight (TKW in grams) — both give the same result.
Enter Germination Rate and Field Emergence Loss
Find the germination percentage on your seed tag and enter it in the Germination Rate field. This is the lab-tested germination under ideal conditions. Then enter an estimated Field Emergence Loss — typically 5–15% — representing additional seeds that germinate but fail to establish in field conditions. Entering your germination rate will auto-suggest 10% emergence loss as a starting point.
Enter Field Area and Row Spacing
Enter your total field area in acres or hectares to calculate how many total pounds or kilograms of seed to order. Enter your row spacing (in inches or cm) to get seeds per row foot — the practical output used to set planter population. Optionally enter your seed price and price unit to calculate total seed cost for the field.
Review Results and Calibrate Your Planter
The seeding rate is shown in lbs/acre, kg/ha, seeds/acre, and bu/acre. The stacked bar chart shows the fate of every 100 seeds sown — how many reach the stand, how many fail to emerge, and how many never germinate. Use seeds per row foot to calibrate your planter. Export the results as CSV for your field records or print them for reference in the cab.
Frequently Asked Questions
What is the difference between germination rate and emergence rate?
Germination rate (from your seed tag) is the percentage of seeds that sprout under ideal lab conditions — controlled temperature, moisture, and substrate. Field emergence rate is lower because seeds must also push through soil, survive temperature extremes, pathogen pressure, and imperfect seed-to-soil contact. As a rule of thumb, field emergence is typically 5–15 percentage points below lab germination. In ideal seedbed conditions (warm, moist, good tilth), the gap may be only 5%. In cold, wet, or crusted soils, the gap can be 20–30%. Always use the combined loss — germination loss plus field emergence loss — when calculating seeding rates. This calculator separates them so you can see how each factor affects your final seeding rate.
What is Thousand Kernel Weight (TKW) and how is it used?
Thousand Kernel Weight (TKW), also called Thousand Seed Weight (TSW), is the weight in grams of exactly 1,000 seeds. It is the standard metric for seed size used in Canadian and European agronomy. TKW and seeds per pound are interconvertible: seeds per lb = 453,592 ÷ TKW (grams). For example, wheat with a TKW of 35 g has approximately 453,592 ÷ 35 = 12,960 seeds per pound. Canola with a TKW of 4.5 g has approximately 100,800 seeds per pound. TKW varies significantly within a crop species — large-seeded soybean varieties have TKW of 150–200 g while small-seeded lines may be 100–130 g. Always use your specific seed lot's actual TKW when precision matters.
How does seeding method affect the required seeding rate?
Different seeding methods distribute seed with different levels of uniformity. A precision planter (corn or soybean row unit) places each seed individually at a precise spacing and depth, achieving near-100% placement efficiency — no seeding method adjustment needed. A standard grain drill distributes seed through fluted rollers and hoses with somewhat less precision — apply a 5% upward adjustment. An air seeder (commonly used for canola and wheat in the Northern Plains and Canada) has further seed distribution challenges — use 8% more. Broadcast seeding (surface spreading without incorporation) loses the most seed to poor seed-to-soil contact and requires 15–20% more seed. Always incorporate broadcast seeding with tillage or use rain to improve contact.
What is seeds per row foot and how do I use it for planter calibration?
Seeds per row foot (or seeds per linear foot of row) is calculated as: target plants per acre × row spacing in feet ÷ 43,560. At 32,000 plants/acre and 30-inch rows (2.5 feet), seeds per row foot = 32,000 × 2.5 ÷ 43,560 = 1.84 seeds per foot. To calibrate your corn planter, mark a measured length of row (e.g., 17 feet 5 inches = 1/1000 acre at 30-inch rows), plant a test strip, pick up the seeds, and count. If you expect 32 seeds per 1000-acre strip and count 30, your population is low; adjust your planter drive or controller accordingly. This is the most direct and reliable calibration method, superior to relying solely on a controller's theoretical population setting.
How do I calculate my total seed order for a field?
Once you have the seeding rate in lbs/acre, multiply by the total field area in acres to get total pounds of seed needed. For example, 1.5 lbs/acre × 100 acres = 150 lbs of seed. Convert to bags: 150 lbs ÷ 50 lbs/bag = 3 bags. In metric: kg/ha × ha = total kg ÷ 1,000 = tonnes. This calculator does this automatically when you enter a field area. Always order 5–10% more than the theoretical minimum to allow for planter calibration runs, field corners and headlands, re-planting of poor emergence areas, and any metering inefficiency. Running out of seed mid-field is a costly operational disruption.
What target plant populations are recommended for major crops?
Target populations vary widely by crop and region. Corn: 28,000–36,000 plants/acre (7–9 plants/m²) — higher in short-season, irrigated, or high-input environments. Soybeans: 100,000–160,000 plants/acre (25–40/m²). Winter wheat: 1.0–1.5 million plants/acre (250–375/m²) — lower for early planting, higher for late planting. Canola: 50–80 plants/m² at emergence (not seeds/m² — emergence rate is variable). Corn seeded late (after optimal window): increase by 5–10% to compensate for lower individual plant yield. These are guidance values; consult your local extension office or seed company agronomist for variety-specific and region-specific recommendations.