Grass Seed Calculator

How much grass seed do you need?

Buying grass seed is a Goldilocks problem. Too little and your lawn comes in thin and patchy, leaving bare soil for weeds to colonize. Too much and the seedlings fight each other for water, light, and nutrients, which actually weakens the stand. This calculator uses the standard turf formula: pounds = area ÷ 1000 × seeding rate. Enter your square footage, pick your goal, and you get the exact amount to buy.

New lawn vs. overseeding rates

Seeding rates are given in pounds per 1,000 square feet and depend on what you're doing. A brand-new lawn from bare soil needs a heavier rate, roughly 5 to 8 lb per 1,000 sq ft, because every seed has to establish from scratch. Overseeding an existing lawn to thicken it up uses a lighter 3 to 4 lb, since the turf is already there and you're just filling gaps. The exact number within those ranges varies by grass type: fine fescue and ryegrass sow heavier than Kentucky bluegrass. Check your seed bag and nudge the rate field to match.

How to use it

1. Measure your lawn and enter the total area in square feet (length × width for a rectangle).
2. Choose New lawn or Overseed to load a typical seeding rate.
3. Fine-tune the rate to match your seed bag's label if you like.
4. Read the pounds needed, then use the rounded-up figure when you shop.

FAQ

How do I find my lawn's square footage?

For a rectangle, multiply length by width. For odd shapes, break the yard into rectangles and circles, calculate each, and add them up.

Which seeding rate should I pick?

Use the higher end of new-lawn rates for fast, dense cover on bare soil, and the lighter overseed rate when you're just thickening existing grass.

Should I round up when buying?

Yes. Seed is sold in whole-pound bags, and a small surplus covers spots you seed a little heavy or want to patch later.

Are these numbers exact?

These are planning estimates, not professional advice. Always follow the rate printed on your specific seed bag, since it's tuned to that variety.