Grass Seed Calculator
Seed pounds, bags to buy, and rate used from lawn area, grass type, and job.
What it does
Grass seed rates track seed size: big tall fescue seed sows near 7 lb per 1,000 ft2 while tiny bermuda needs only about 1.5. Overseeding into existing turf halves whatever the bare ground rate would be.
The tool above takes lawn area with grass type and job in either system. It returns seed weight with bags to buy and the rate used beside them.
The default of 5,000 ft2 of tall fescue new lawn at 7 lb/M needs 35 lb: four 10 lb bags. The metric mirror of 465 m2 needs 15.9 kg: four 5 kg bags. Overseeding bluegrass on the same lawn needs just 5 lb.
The rates follow university extension lawn guidance with a second extension program matching each figure. Both place tall fescue near 6 to 8, bluegrass near 2, fine fescue near 4.5, ryegrass near 8, and bermuda near 1.5 lb per 1,000 ft2.
How to use
- Pick imperial (ft2, lb) or metric (m2, kg).
- Measure the lawn area edge to edge.
- Pick the grass type actually sown.
- Pick new lawn or overseed for the rate.
- Read pounds first, then round bags up.
Formula
- rate
- Pounds per 1,000 ft2 (lb/M) for the species.
- 1/2
- Overseed factor into existing turf.
- bags
- Whole bags rounded up, one production run.
Metric converts area to ft2 first (x 10.7639), then runs one path, so systems agree. Bag labels and local extension advice beat every estimate when they differ.
Worked example
Example: 5,000 ft2 tall fescue, new lawn
Imperial defaults: fescue, new, 5000 ft2.
- Rate: tall fescue new lawn is 7 lb/M.
- Units: 5,000 / 1,000 = 5.
- Seed: 5 x 7 = 35 lb.
- Bags: 35 / 10 = 3.5, round up to 4 x 10 lb bags.
- Tool shows 35 lb, 4 x 10 lb bags, 7 lb per 1,000 ft2 (new).
Reference table
| Grass | Rate | 5,000 ft2 needs |
|---|---|---|
| Turf-type tall fescue | 7 lb/M | 35 lb |
| Kentucky bluegrass | 2 lb/M | 10 lb |
| Fine fescue | 4.5 lb/M | 22.5 lb |
| Perennial ryegrass | 8 lb/M | 40 lb |
| Bermudagrass hulled | 1.5 lb/M | 7.5 lb |
Limits
- Planning rates only; bag labels and local advice win.
- Blends need each share weighed separately.
- Coated seed covers fewer seeds per pound.
- Shade, slope, and irrigation shift real results.
Common mistakes
- Sowing one rate for every species.
- Full rating an overseed job and crowding seedlings.
- Skipping soil prep and blaming the seed.
- Buying bags across production runs with color drift.
- Seeding warm grasses into cold soil windows.
Try it yourself
Quick checks. Answers sit tucked under each question.
5,000 ft2 KBG overseed?
Rate 1 lb/M: 5 lb, 1 x 10 lb bag.
Metric 465 m2 fescue new?
5,005 ft2 equivalent: 15.9 kg, 4 x 5 kg bags.
Why so little bermuda?
Two million seeds per pound against fescue near a quarter million.
Questions
How much seed per 1,000 sq ft?
Tall fescue 6 to 8 lb, bluegrass near 2, fine fescue 4.5, ryegrass near 8, bermuda near 1.5.
New lawn or overseed rate?
Overseed at half the new lawn rate into existing turf.
What does lb/M mean?
Pounds per 1,000 square feet (M is thousand in turf shorthand).
How many bags?
Seed pounds divided by bag size, rounded up. 35 lb is four 10 lb bags.
Can I mix species?
Yes in blends, but weigh each share by its own rate, not one average.
When to seed cool grasses?
Early fall in most regions: warm soil with cooling air and fewer weeds.