Seed Rate Calculator

Calculate optimal planting populations and seeding rates for corn, wheat, soybeans, and other field crops

Seed Rate Calculator

Calculate optimal seeding rates for agricultural crops with planting density and cost analysis

Seeding Parameters

Crop Selection

Field Area (hectares)

Enter the total area to be seeded

Seeding Equipment

Optional Adjustments:

Custom Target Population (plants/m²)

Leave empty to use crop default

Custom Germination Rate (%)

Leave empty to use crop default

Seeding Recommendations

134.5 kg/ha

Seeding Rate

Total Seed Required:

1344.5 kg

Estimated Cost:

$1613.45

Target Population:

400 plants/m²

Germination Rate:

85%

Equipment Adjustment:

100%

Crop Information:

Cereals

Temperate

15cm rows

2.5cm depth

Planting Window: September - November
Soil Type: Well-drained loam

Note: These are baseline recommendations. Adjust based on local conditions, seed quality, and farming practices.

Agricultural Disclaimer: These calculations provide general guidance based on typical crop requirements. Actual seeding rates should be adjusted based on local conditions, seed quality, field history, and consultation with agricultural professionals.

Recommended Seeding Rates by Crop (US Reference)

Crop	Target Plant Population	Seeding Rate	Row Spacing	Notes
Corn (grain)	28,00036,000 plants/acre	30,00038,000 seeds/acre	30"	Adjust for field productivity
Soybeans	100,000140,000 plants/acre	120,000180,000 seeds/acre	30" or 15"	Higher rates for narrow rows
Winter Wheat	900,0001,200,000 plants/acre	1.01.5 million seeds/acre	67"	1.21.8 bu/acre typical
Canola	200,000300,000 plants/acre	46 lbs/acre	1214"	~35 seeds/sq ft
Sunflower	20,00026,000 plants/acre	22,00030,000 seeds/acre	30"	Lower for dryland
Grain Sorghum	50,000100,000 plants/acre	56,000110,000 seeds/acre	30"	Wider range by region
Alfalfa	2025 plants/sq ft	1520 lbs/acre	618"	Pure stand
Forage Grasses	Varies	825 lbs/acre PLS	612"	Pure live seed (PLS) basis

Sources: Purdue, Iowa State, University of Nebraska Extension recommendations. Rates vary by region, soil type, and hybrid selection.

Seeding Rate Formula

Basic formula:
Seeding Rate = Target Population (Germination% Emergence%)

lbs/acre from seeds/acre:
lbs/acre = (Seeds/acre Seeds/lb)

Seeds per lb varies widely: corn ~1,4001,600, wheat ~12,00014,000, soybeans ~2,4003,200, canola ~120,000150,000.

Reading a Seed Tag

Every commercial seed bag includes: Lot Number (for traceability), Germination% (lab test result), Pure Seed% (labeled variety purity), Inert Matter%, Weed Seed%, Test Date (must be within 9 months for most crops). The germination test was conducted under ideal lab conditions expect 515% lower field emergence. Use the lower field estimate when calculating seeding rates for critical stands.

Frequently Asked Questions

How do I calculate the seed rate needed for a target plant population?

Formula: Seeding Rate (seeds/acre) = Target Plant Population (Germination Rate Field Emergence Factor). For example: target 30,000 corn plants/acre, seed germination 95%, field emergence 90%: 30,000 (0.95 0.90) = 30,000 0.855 = 35,088 seeds/acre. The field emergence factor (typically 8595%) accounts for soil conditions, planting depth, insects, and other field losses beyond laboratory germination tests.

What is the difference between seeding rate and target plant population?

Target plant population is the desired number of plants growing in the field at harvest. Seeding rate is the number of seeds planted per acre to achieve that population, accounting for germination rate and field emergence losses. Not every seed planted becomes a plant germination rates range from 8099% on seed tags, and additional losses of 515% occur in the field from soil conditions, pests, disease, and planting errors.

How does row spacing affect optimal seeding rates?

Narrower row spacing (15" vs 30" for soybeans) allows more light interception earlier in the season, which can support higher plant populations and often increases yield 25% in high-productivity environments. For corn, moving to 20" rows vs 30" allows more uniform plant distribution which reduces within-row competition at the same seeding rate. However, narrow rows require compatible equipment and may increase disease pressure at high populations.

What is Pure Live Seed (PLS) and why does it matter?

Pure Live Seed (PLS) is the percentage of a bag of forage or grass seed that consists of viable seeds of the labeled species. PLS% = (Purity% Germination%) 100. For example, a bag labeled 98% pure, 85% germination has 83.3% PLS. Seeding rates for forages and grasses are always stated on a PLS basis. If a recommendation calls for 10 lbs/acre PLS and your seed is 83.3% PLS, you need to plant 10 0.833 = 12 lbs of actual seed per acre.

How does planting date affect seeding rates?

Late planting often warrants higher seeding rates to compensate for reduced growing season. For corn planted after optimal date (typically June 1 in the US Corn Belt), increase seeding rate by 1,0002,000 seeds/acre per week of delay to maintain yield potential. Early-planted wheat may use lower rates (1.01.2 million seeds/acre) while later-planted wheat benefits from higher rates (1.41.8 million seeds/acre) to compensate for less fall tillering.