Grass seed calculator for turf (lb per 1,000 ft², bulk or PLS)
Seeding rates are written per 1,000 ft², but seed is sold by the bag. A seed calculator turns a seeding rate into pounds of seed and bags for your area, and, when the rate is in pure live seed (PLS), adjusts for the purity and germination on the seed tag.
Free to use. No sign-up, no email.
Results
- Seed needed
- 74.3 lb
- Bags needed (rounded up)
- 3
- Bulk seed rate
- 3.72 lb/1,000 ft²
- Pure live seed in the bag
- 80.8 %
Always follow the product label.
The formula behind the seed calculator
Pure live seed
PLS % = purity % × germination % ÷ 100
Bulk rate from a PLS rate
bulk lb per 1,000 ft² = PLS lb per 1,000 ft² ÷ (PLS % ÷ 100)
Seed and bags
seed = rate × area (ft²) ÷ 1,000 · bags = seed ÷ bag size, rounded up
Where the numbers come from
- Pure live seed (PLS): PLS % = germination % × purity % ÷ 100. University of Wisconsin–Madison Extension, “Pure Live Seed”
- Seed tag minimums used in the example: 95 % purity and 85 % germination give 80.75 % PLS (creeping bentgrass row). UMass Extension Turf Program, “Seeding Rate Considerations”, Table 1
- Pound, foot and acre: 1 lb = 453.59237 g, 1 ft = 0.3048 m, 1 acre = 43,560 ft² (all exact). NIST Handbook 44 (2024), Appendix C
Worked example (the calculator opens with these numbers)
- Example inputs (not a recommended rate): 3 lb PLS per 1,000 ft², seed tag 95 % purity and 85 % germination, 20,000 ft², 25 lb bags.
- PLS: 95 × 85 ÷ 100 = 80.75 %.
- Bulk rate: 3 ÷ 0.8075 = 3.72 lb per 1,000 ft².
- Seed needed: 3.7152 × 20 = 74.3 lb.
- Bags: 74.3 ÷ 25 = 2.97, so 3 bags.
The 95 % and 85 % are the creeping bentgrass minimums in the UMass table, which gives 80.75 % PLS — the same result.
Questions about the seed calculator
What is pure live seed (PLS)?
Pure live seed is the share of a bag that is the seed you want and will germinate: purity percent times germination percent, divided by 100.
Should I enter a bulk rate or a PLS rate?
Enter the seeding rate the way your recommendation gives it. If the rate is in pure live seed, choose PLS and enter purity and germination from the seed tag; the seed calculator then works out the bulk seed to buy.
What seeding rate should I use?
The seed calculator does not choose a rate. Use the rate on the seed label or from your extension service or agronomist for your grass and situation.
Get this for your actual course
Atlas maps every green, tee and fairway with its area, so seeding and renovation plans start from your own ground. Areas are approximate.
Questions? info@aetherisintel.com