How to use this calculator
- Choose sod or seed. The arithmetic is completely different: sod is an area divided by a piece size, seed is an area multiplied by a rate.
- Measure the lawn. Lawns are almost never rectangles. Split the area into as many rectangles as it takes — around the drive, behind the garage, the strip along the fence — and add a section for each. Curved edges: measure the widest and narrowest points and average them.
- For sod, check what your supplier’s pallet holds. Growers ship 450 or 500 square feet. Over four pallets that difference is 200 square feet, which is a whole extra pallet you either need or do not.
The formula
sod: area to cover = measured area × (1 + waste %)
pieces = area to cover ÷ sq ft per piece, rounded up
seed: pounds = (area ÷ 1,000) × rate (lb per 1,000 sq ft)
Worked example — a 2,400 sq ft lawn:
As sod, on 450 sq ft pallets with 10% for cuts:
- Area to cover: 2,400 × 1.10 = 2,640 sq ft
- Pallets: 2,640 ÷ 450 = 5.87, so 6 pallets
As turf-type tall fescue seed at 6–8 lb per 1,000 sq ft:
- 2,400 ÷ 1,000 = 2.4 thousand square feet
- 2.4 × 6 = 14.4 lb, 2.4 × 8 = 19.2 lb → buy 20 lb
The cost difference between those two lines is usually a factor of ten or more. That is the real decision this page exists to inform.
Seeding rates
| Grass | lb per 1,000 sq ft |
|---|---|
| Kentucky bluegrass | 2–3 |
| Perennial ryegrass | 4–5 |
| Turf-type tall fescue | 6–8 |
| Fine fescues | 4–5 |
| Overseeding an existing lawn (perennial rye) | 4–6 |
These are Penn State Extension’s figures from Table 1 of their lawn establishment guidance, chosen to give roughly 1,000 to 2,000 seedlings per 1,000 sq ft. Southern extension services sometimes publish slightly lower rates for tall fescue, and the bag will carry its own recommendation — follow the bag when they disagree.
Two things the table does not say:
- More seed is not a better lawn. Over-seeding a new lawn produces dense, spindly seedlings that compete with each other and thin out badly in the first dry spell.
- Rates are for bare soil. Overseeding an existing lawn uses less, because you are filling gaps rather than establishing a stand.
Sod: sizes and how much extra
A standard roll covers about 10 square feet. A pallet holds 450 to 500 square feet depending on the grower.
Order 5 to 10 percent extra. Sod gets cut to fit around beds, paths, trees and curves, and the offcuts are usually too small or too odd-shaped to use anywhere else. The reason to be less stingy here than with other materials is that sod is perishable: it is a living crop, harvested to order, and it starts declining the moment it is cut. Running short means a second delivery days later, from a different cut, in a slightly different colour, laid next to grass that has already begun to yellow at the edges.
Plan to lay it the day it arrives, and water it the same day.
Ground preparation matters more than the sod
This is the part that determines whether the lawn is still good in three years.
Sod laid on compacted, unamended ground roots shallowly and thins within a season or two. It looks perfect for about six weeks. The usual target is four to six inches of decent topsoil, graded smooth and lightly firmed — enough to walk on without leaving deep prints, not rolled solid.
If you need to work out how much soil that is, the topsoil calculator does the same arithmetic for soil depth.
The same applies to seed, with an added complication: seed needs consistent moisture for weeks while it germinates and establishes. If you cannot water reliably during that window, sod is the more realistic choice even though it costs more.
Sod or seed?
Sod gives you a finished lawn the day it is laid and holds soil immediately, which matters on any slope. It costs several times what seed does, and it must be laid promptly.
Seed is far cheaper and gives you more choice of cultivar, but it needs weeks of watering, it gives weeds an opening while the grass is thin, and on a slope the first heavy rain can take the seed with it.
On a slope, or anywhere erosion is a real risk, sod usually wins regardless of the price difference.
Timing
For cool-season grasses — bluegrass, ryegrass, the fescues — late summer into early autumn is the best window. The soil is still warm enough for fast germination, the air is cooling, and annual weeds are past their most aggressive phase. Spring is the second-best option, and summer seeding of cool-season grass mostly wastes seed.
Sod can go down whenever the ground is not frozen, provided you can keep it watered.
This is an estimate. Pallet coverage varies by grower and seeding rates vary by region and cultivar. Confirm the pallet size with your supplier and the rate on the seed bag before you order.