Grass Seeding Rate Calculator
Kentucky Bluegrass (2-3 lbs/1k sq ft)
Tall Fescue (6-8 lbs/1k sq ft)
Perennial Ryegrass (5-9 lbs/1k sq ft)
Fine Fescue (3-5 lbs/1k sq ft)
Bermuda Grass (1-2 lbs/1k sq ft)
Zoysia Grass (1-2 lbs/1k sq ft)
Bahia Grass (6-10 lbs/1k sq ft)
Centipede Grass (0.25-0.5 lbs/1k sq ft)
Buffalo Grass (2-3 lbs/1k sq ft)
New Lawn (Bare Soil)
Overseeding Existing Lawn
Calculation Results
Recommended Rate:
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Total Seed Required:
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Bags to Buy:
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Estimated Cost:
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How to Calculate Grass Seed Requirements
Calculating the correct amount of grass seed is critical for establishing a lush, healthy lawn. Applying too little seed results in a thin lawn that is susceptible to weed invasion, while applying too much seed causes competition between seedlings for light and nutrients, often leading to damping-off disease or weak root systems.
1. Determine Your Lawn Area
Before you can calculate the seed needed, you must know the square footage of your yard. To do this, measure the length and width of the area you intend to seed. Multiply the length by the width to get the area in square feet.
Formula: Length (ft) × Width (ft) = Area (sq ft)
2. Choose Your Project Type: New vs. Overseeding
The seeding rate changes significantly depending on whether you are planting a brand new lawn on bare soil or overseeding an existing thin lawn.
- New Lawn: Requires the full recommended seeding rate to ensure complete coverage.
- Overseeding: Typically requires 50% (half) of the new lawn rate because you are filling in gaps rather than covering bare earth.
3. Identify Grass Species Rates
Different grass species have vastly different seed sizes and growth habits, which dictate how many pounds are needed per 1,000 square feet.
| Grass Type | New Lawn Rate (lbs/1k sq ft) | Overseeding Rate (lbs/1k sq ft) |
|---|---|---|
| Kentucky Bluegrass | 2 – 3 lbs | 1 – 1.5 lbs |
| Tall Fescue | 6 – 8 lbs | 3 – 4 lbs |
| Perennial Ryegrass | 7 – 9 lbs | 3.5 – 4.5 lbs |
| Bermuda Grass | 1 – 2 lbs | 0.5 – 1 lbs |
| Centipede Grass | 0.25 – 0.5 lbs | 0.125 – 0.25 lbs |
4. The Calculation Formula
Once you have your area and your specific grass rate, the math is straightforward:
Total Seed (lbs) = (Lawn Area ÷ 1,000) × Seeding Rate
For example, if you are overseeding a 5,000 sq ft lawn with Tall Fescue (using a rate of 4 lbs per 1,000 sq ft):
(5,000 ÷ 1,000) × 4 = 20 lbs of seed needed.
Tips for Success
- Account for Waste: It is often wise to buy 10-15% more seed than calculated to account for birds, washout from rain, or uneven spreading.
- Check the Label: Always check the seed bag label for "Pure Live Seed" (PLS) percentage. If a bag has a lot of inert matter or weed seed, you may need to increase your rate.
- Spreader Settings: Calibrate your broadcast or drop spreader according to the seed manufacturer's recommendations to ensure you are applying the calculated rate accurately.