Grass seed calculator
Work out how much seed product to buy using the rate printed on your chosen mix. Keep new-lawn seeding and overseeding separate so a single default rate does not overstate or understate the order.
The interactive calculator requires JavaScript. The formula and worked example below are available without it. No sign-up is required.
How to use this calculator
- Measure only the lawn being seeded; exclude the house, driveway, and planting beds.
- Find the product label rate for overseeding or starting a new lawn.
- Enter the bag weight to see the number of whole bags and total product purchased.
The formula
Pounds of seed product = square feet ÷ 1,000 × label rate in pounds per 1,000 square feet. Bag count = pounds needed ÷ bag weight, rounded up.
Worked example
A 5,000 sq ft lawn at an example label rate of 4 lb per 1,000 sq ft needs 20 lb of product, or two 10-lb bags. The rate is illustrative; use your own product and task instructions.
The seed label sets the rate
Turfgrass species, mixtures, and coatings vary. University of Minnesota Extension explains how to read seed composition and choose a mix. This calculator uses your label rate rather than guessing the right species or rate for a Cincinnati yard.
New lawn or thin lawn?
A bare seedbed and an established lawn with thin spots are different jobs. Check that the application rate is for the work you are doing. Do not count intact areas that you do not intend to seed.
Prepare before buying extra seed
Quantity is only part of the plan. Review soil contact, timing, moisture, and the cause of bare areas. For a Greater Cincinnati property, discuss the site and seasonal conditions before scheduling aeration or overseeding.
Common questions
How much grass seed do I need for an acre?
An acre is 43,560 square feet. Multiply the label rate per 1,000 square feet by 43.56. The acres option performs that conversion for you.
Does this correct for coated seed?
No. Use the bag’s product application rate and product weight together. Do not combine a pure-seed rate with coated-product weight unless the label supplies a conversion.
Will buying more seed make the lawn fill in faster?
Do not exceed the label rate based on this calculator. It is a quantity tool, not a recommendation to increase application rates.
Sources & method
Calculations use the formulas shown above. These references inform the planning guidance; they do not endorse this tool. References checked on .
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