🚜 Tractor Horsepower Calculator
Determine the minimum and recommended tractor horsepower for your operation based on primary implement width, tillage depth, soil type, and target field speed.
1. Planting Population
Yield CatalystCalculate target plants per acre and seed bag metrics based on spatial planting profiles.
Understanding Seed Seeding Rates by Weight
For crops like wheat, barley, oats, and canola, seeding rates are often calculated by weight (lbs/acre or kg/ha) rather than seeds per acre. Thousand Kernel Weight (TKW) is the most accurate way to convert your target plant population into a bulk planting weight.
How It Works (Formula)
The formula multiplies your target population by the TKW, and then adjusts for germination and seed purity to ensure you plant enough viable seeds.
Formula: Seed Rate (lbs/ac) = (Target Population × TKW (g)) / (Germination % × Purity % × 453.6)
Input Guide
- Thousand Kernel Weight (TKW): The weight in grams of 1,000 seeds. Found on your seed tag.
- Seed Purity: The percentage of the bag that is actual seed (not chaff or weed seed).
- Target Plant Stand: How many plants you want to emerge per acre.
Example Calculation
Targeting 1,200,000 wheat plants/acre with a TKW of 35 grams, 95% germination, and 99% purity:
Base Weight = (1,200,000 * 35) / 453.6 = 92,592 grams = ~204 lbs/acre
Adjusting for 95% germination and 99% purity requires a final planting rate of ~217 lbs/acre.
About This Tool
Frequently Asked Questions
How do I know what HP tractor I need?
A general rule is to allow 5–10 HP per foot of tillage width depending on soil type and tillage depth.