BYTETOOLS

Grass Seed Calculator

Calculate grass seed from lawn area and grass type using published new-lawn and overseeding rates, plus the starter fertiliser to hit a target nitrogen rate.

4,800
Lawn area (sq ft)
445.9
Lawn area (m²)
4.80
Thousands of sq ft
33.6
Seed needed (lb)
15.24
Seed needed (kg)
34.2
Sowing rate (g per m²)
2
Seed bags to buy
$120.00
Estimated seed cost
26.7
Starter fertiliser (lb)
12.10
Starter fertiliser (kg)
1
Fertiliser bags to buy

Seed weight = (area ÷ 1,000 sq ft) × the seeding rate. The built-in rates are the midpoints of the ranges published by US turf extension programmes — 6 to 8 lb per 1,000 sq ft for a new tall fescue lawn, 2 to 3 for Kentucky bluegrass, 1 to 2 for hulled bermuda — halved to roughly a third for overseeding. Starter fertiliser = target lb of nitrogen ÷ the nitrogen percentage on the bag, so 1 lb N from an 18-24-12 takes 5.6 lb of product per 1,000 sq ft. Sowing much heavier than the label rate crowds the seedlings and invites disease. Estimates only — sow at the season your species actually germinates in.

What is the Grass Seed Calculator?

The ByteTools Grass Seed Calculator works out how much seed a lawn needs and how many bags that is. Enter the area, pick the grass type, say whether you are starting from bare soil or overseeding, and it applies the appropriate seeding rate per 1,000 square feet, then converts the result into pounds, kilograms, grams per square metre and bags.

  • New-lawn and overseeding rates for eight common grass types
  • Seed weight in pounds, kilograms and grams per square metre
  • Bag counts and cost from your own bag weight and price
  • Starter fertiliser from a target nitrogen rate and the bag's N percentage
  • Every rate editable, so the label on your bag always overrides the default
  • All calculated in your browser — nothing uploaded, no signup

How to use the Grass Seed Calculator

  1. 1

    Choose imperial or metric, then work from the lawn length and width or from a known area.

  2. 2

    Say whether this is a new lawn or an overseed, and pick the grass type.

  3. 3

    Check the seeding rate it fills in and edit it to match the rate printed on your seed bag.

  4. 4

    Enter the seed bag weight and price.

  5. 5

    Set the target nitrogen rate, the fertiliser's nitrogen percentage and its bag weight, then read the seed and fertiliser totals.

About the Grass Seed Calculator

The ByteTools Grass Seed Calculator works out how much seed a lawn needs and how many bags that is. Enter the area, pick the grass type, say whether you are starting from bare soil or overseeding, and it applies the appropriate seeding rate per 1,000 square feet, then converts the result into pounds, kilograms, grams per square metre and bags.

The built-in rates are the midpoints of the ranges published by US university turf extension programmes: 6 to 8 lb per 1,000 sq ft for a new tall fescue lawn, 2 to 3 for Kentucky bluegrass and 1 to 2 for hulled bermuda, with overseeding rates roughly a third to a half lower. Every rate is editable, so your own seed bag always wins.

It also sizes the starter fertiliser: pounds of product = target nitrogen ÷ the nitrogen percentage on the bag, so 1 lb of N from an 18-24-12 takes 5.6 lb of product per 1,000 sq ft. Everything runs locally in your browser with nothing uploaded. Estimates only — sow in the season your species actually germinates in.

Frequently asked questions

How much grass seed do I need per 1000 square feet?

It depends on the species. Tall fescue and perennial ryegrass want 6 to 8 lb per 1,000 sq ft for a new lawn, Kentucky bluegrass only 2 to 3, and hulled bermuda 1 to 2. Overseeding an existing lawn takes roughly half to two-thirds of the new-lawn rate.

How much grass seed do I need for 5000 square feet?

At 7 lb per 1,000 sq ft, a new tall fescue lawn of 5,000 sq ft needs 35 lb of seed — two 20 lb bags. The same area seeded with Kentucky bluegrass at 2.5 lb per 1,000 needs only 12.5 lb, because bluegrass seed is far smaller and spreads by rhizomes once established.

Can I use more seed to get a thicker lawn?

Not really, and heavy over-seeding backfires. Seedlings that germinate too close together compete for light, water and nutrients, grow thin and spindly, and are far more prone to damping-off disease. Stay near the label rate and put the extra effort into soil preparation and watering.

How much starter fertiliser do I need for a new lawn?

Aim for about 1 lb of actual nitrogen per 1,000 sq ft. Divide that by the nitrogen percentage on the bag: an 18-24-12 starter is 18% N, so you need 5.6 lb of product per 1,000 sq ft — 28 lb for a 5,000 sq ft lawn.

Is seeding cheaper than laying sod?

Substantially, usually by an order of magnitude on materials alone. The trade-off is time and risk: sod is an instant lawn you can walk on within weeks, while seed needs consistent watering for a month or more and can fail outright if the weather turns against it.

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