SumsibleMEASURE · ESTIMATE · PLAN
QUANTITY WORKSHEET / 08

Grass seed calculator

Estimate seed weight and bags from your label rate, for new lawns or overseeding.

How to use this calculator
  1. Measure the lawn sections or enter their known area; exclude paths and other surfaces that will not receive seed.
  2. Choose new lawn or overseeding. Enter the corresponding bag-label rate in lb per 1,000 ft² or g per m²; switching use clears the previous rate.
  3. Enter the exact bag weight. Extra allowance means reserve stock to purchase, not a higher application rate. Save the seed separately from soil.
Material quantity calculator

Your measurements

Units

Example values are loaded. Replace them with your measurements and product details.

Measurement method
Deduct a door, window or rectangle

Adds width × height × count to this area’s exclusions, per identical copy. Do not deduct it twice.

MATERIAL & ALLOWANCES

Label use
My bag lists coverage instead of a rate

Check the net bag weight above, then enter the area that this exact bag covers for the selected new-lawn or overseeding use. This fills application rate = bag weight ÷ coverage.

Use the rate on your chosen seed label. No grass selection, growing conditions, spreader settings or application advice is provided.

Buy seed using the rate for your actual project

A grass seed bag can state different coverage for bare ground and for an existing lawn. This worksheet uses the application rate you enter for the selected use. It does not choose a grass species or assume that a front-of-bag coverage applies to new planting.

The label rate converts measured area to product weight. A separate allowance adds reserve stock to buy; it does not instruct you to spread that extra seed. Compatible saved areas combine their unrounded weight before whole-bag rounding and stock deduction.

Area = sum((measured footprint − exclusions) × copies) Seed weight = area × label application rate Purchase requirement = seed weight × (1 + extra allowance / 100) Bags = round up(purchase requirement / net bag weight)

Understand the inputs

Label use
Select new lawn / bare area or overseeding. Changing this selection clears the rate so an earlier value cannot silently become the rate for a different job.
Application rate
US: pounds per 1,000 square feet. Metric: grams per square meter. If the label gives bag coverage instead, rate = bag weight ÷ stated coverage; multiply by 1,000 for lb per 1,000 ft². Use coverage for the selected use.
Bag weight
The weight to which that label rate applies. Do not substitute pure-seed weight for a coated or blended product’s stated purchase weight.
Extra purchase allowance
Optional reserve to buy, not a planting recommendation. The example is zero. Rates, package sizes and allowances remain your inputs.

Example: a front lawn and a narrow side strip

A 30 ft × 20 ft lawn and a 10 ft × 20 ft strip total 800 ft². Suppose the selected product’s label calls for 4 lb per 1,000 ft² for the intended use. The calculated need is 3.2 lb. With no extra allowance and a 3 lb bag, the purchase count is two bags, leaving 2.8 lb of package capacity after that estimated use. This rate and bag size are illustrative, not a recommended product or dose.

Common estimating mistakes

  • Using the larger overseeding coverage figure for a bare area.
  • Entering pounds per acre in a field labeled pounds per 1,000 square feet.
  • Treating the extra bag caused by rounding as a direction to spread more seed.
  • Combining different species, blends, coatings, lots or label rates under an incomplete product name.

What this estimate leaves out

No selection of species, season, climate, soil preparation, irrigation, fertilizer, chemical treatment, spreader setting or germination outcome is provided. Keep those decisions with the product instructions and qualified local guidance. The calculation assumes a uniform entered rate within each estimate.

Product information & references

US manufacturer instructions distinguish new-lawn and overseeding coverage. Use the current label for your chosen product, not the examples in this worksheet.