Winter Wheat Seed Rate Calculator

Winter Wheat Seed Rate Calculator

Calculate the precise pounds per acre needed based on your target stand and seed characteristics.

Typically 1.2 to 1.6 million for winter wheat.

Check your seed lot tag. Crucial for accuracy.

Combines germination rate and expected field loss. Typically 80-90% for good conditions.

Required Seeding Rate:

0 lbs/acre

Seeding Metrics:

• Total Seeds Dropped per Acre: 0
• Seeds per Square Foot: 0
• Approx. Seeds/Foot (7.5″ spacing): 0

function calculateWheatSeedRate() { // 1. Get inputs var targetMillionsStr = document.getElementById('ww_target_millions').value; var tgwStr = document.getElementById('ww_tgw').value; var establishmentStr = document.getElementById('ww_establishment').value; // 2. Validate inputs if (targetMillionsStr === "" || tgwStr === "" || establishmentStr === "") { alert("Please fill in all fields."); return; } var targetMillions = parseFloat(targetMillionsStr); var tgw = parseFloat(tgwStr); var establishmentPercent = parseFloat(establishmentStr); if (isNaN(targetMillions) || isNaN(tgw) || isNaN(establishmentPercent) || targetMillions <= 0 || tgw <= 0 || establishmentPercent <= 0) { alert("Please enter valid positive numbers."); return; } // 3. Calculation Logic (Agronomy standard) // Convert millions to actual target plants var targetPlantsPerAcre = targetMillions * 1000000; // Convert establishment percentage to decimal var establishmentDecimal = establishmentPercent / 100; // Calculate total seeds needed to drop to achieve target stand var totalSeedsNeeded = targetPlantsPerAcre / establishmentDecimal; // Calculate seeds per pound based on TGW // There are 453.592 grams in a pound. var seedsPerPound = 453592 / tgw; // Final calculation for lbs per acre var requiredLbsPerAcre = totalSeedsNeeded / seedsPerPound; // Secondary metrics var seedsPerSqFt = totalSeedsNeeded / 43560; // 43560 sq ft in an acre // Seeds per row foot for standard 7.5 inch spacing. // In one acre (43560 sq ft), with 7.5" (0.625 ft) spacing, there are 43560 / 0.625 = 69696 linear feet of row. var linearFeetPerRow = 43560 / (7.5 / 12); var seedsPerRowFoot = totalSeedsNeeded / linearFeetPerRow; // 4. Display Results document.getElementById('ww_final_lbs_acre').innerText = requiredLbsPerAcre.toFixed(1); document.getElementById('ww_seeds_dropped').innerText = totalSeedsNeeded.toLocaleString(undefined, {maximumFractionDigits: 0}); document.getElementById('ww_seeds_sqft').innerText = seedsPerSqFt.toFixed(1); document.getElementById('ww_seeds_rowfoot').innerText = seedsPerRowFoot.toFixed(1); document.getElementById('ww_result_area').style.display = 'block'; }

Moving Beyond "Bu/Acre": The Importance of Precision Seeding in Winter Wheat

For generations, many winter wheat producers have relied on a fixed seeding rate by weight—commonly planting "two bushels per acre" or a flat "120 lbs per acre" regardless of the variety or seed lot. While convenient, this approach ignores a critical biological reality: seed size varies significantly.

Planting by weight without accounting for seed size can lead to stands that are either too thin (reducing yield potential and encouraging weeds) or too dense (increasing disease pressure and lodging risk). Modern agronomy emphasizes planting toward a specific Target Plant Population.

This calculator helps you determine the exact pounds per acre required to achieve your desired final stand, adjusting for the specific characteristics of the seed you are planting this season.

Understanding the Input Variables

• Target Final Stand (Millions/Acre): This is your goal for the number of live, productive plants remaining after winter. For many regions, a target between 1.3 and 1.5 million plants per acre is standard for optimum yield, though this varies by planting date and region. Later planting dates often require higher targets.
• Thousand Grain Weight (TGW): This is the most critical variable changing year-to-year. It is the weight, in grams, of 1,000 seeds. A low TGW (e.g., 28g) means small seeds, so you need fewer pounds to get the same number of plants. A high TGW (e.g., 42g) means large seeds, requiring significantly more pounds per acre. You must find this number on your seed tag or get a sample weighed.
• Expected Establishment Rate (%): Not every seed dropped will become a harvestable plant. This percentage accounts for germination rate (on the tag) minus field losses due to seeding depth, soil crusting, pests, and winter kill. If your tag says 95% germination, and you expect 10% field loss, your establishment rate is roughly 85%.

Example Scenario: The Impact of Seed Size

Consider two farmers aiming for the same target of 1.4 million plants per acre with an 85% establishment rate.

Farmer A (Small Seed): Their seed has a TGW of 30g. Using the calculator, they need to plant roughly 109 lbs/acre.

Farmer B (Large Seed): Their seed has a TGW of 40g. To achieve the exact same stand count as Farmer A, they must plant approximately 145 lbs/acre.

If Farmer B used Farmer A's rate of 109 lbs/acre, their final stand would be significantly lower than the target, potentially costing yield. Precision seeding ensures every field gets the right start.