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Lawn calculator: how much sod or grass seed you need
Calculate how many sod rolls or how much grass seed you need to cover a garden area. Choose the mode based on how you'll plant, adjust the coverage per roll or the seeding rate to match your product, and add a waste margin for edges and irregular shapes.
Last reviewed: September 2026 · How we calculate
Input data
Adjust to your supplier's roll or sod size.
Common range: 25-50 g/m² depending on grass type.
Results
Enter your data and press Calculate.
Results are estimates. Always check the manufacturer's or supplier's specifications before buying.
Unit converter
How to calculate the lawn you need
The calculation changes based on the method: with sod rolls (already-grown grass, ready to lay), you divide the total area by each roll's coverage. With seed, you multiply the area by a seeding rate (grams of seed per m²). Both cases add a waste margin for edges, corners, and irregular ground shapes.
Formula
Area with waste = Area × (1 + Waste ÷ 100)
Sod mode: Rolls = Area with waste ÷ Coverage per roll (rounded up)
Seed mode: Seed = Area with waste × Seeding rate
Worked example (sod rolls)
A 10 × 8 m (33 × 26 ft) garden, rolls covering 1 m² each, and 10% waste — the calculator's defaults:
| Area | 10 × 8 = 80 m² |
|---|---|
| Area with 10% waste | 80 × 1.10 = 88 m² |
| Rolls needed | 88 ÷ 1 = 88 rolls |
In seed mode, that same 88 m² area at a rate of 35 g/m² needs 3.08 kg (6.8 lb) of seed (88 × 35 ÷ 1000). Switch the "Planting method" selector to see both calculations.
Sod vs. seed: which fits your project
| Sod rolls | Instant lawn, usable in days; more expensive per m² and needs to be laid soon after delivery |
|---|---|
| Seed | Much cheaper per m²; takes 4-8 weeks to establish and needs constant watering while germinating |
Sod is the usual choice for small areas, erosion-prone slopes, or when you need the lawn ready right away (before an event, for example). Seed makes sense on large areas where sod's cost per m² would be high, and when you have time to wait for germination.
Preparing the soil before planting
Both sod and seed perform better on well-prepared soil: leveled, free of large rocks, loosened in the top 10-15 cm (4-6 in), with topsoil or compost worked in. If your ground needs fill or substrate improvement before planting, the soil/substrate calculator gives you the exact volume you need.
Common mistakes when calculating a lawn
- Not adding waste on irregular ground. Gardens with curves, plant islands, or non-rectangular shapes generate more trim waste than it seems.
- Using the generic roll coverage without checking the supplier. Sod size varies a lot between nurseries — confirm the real dimensions before buying.
- Seeding without preparing the soil. Seed on compacted ground germinates poorly no matter how much you buy.
- Buying all the sod before the ground is ready. Sod deteriorates fast if not laid within 24-48 hours of delivery; coordinate the purchase with soil prep.
Frequently asked questions
Which gives more coverage for the money, sod or seed?
Seed is much cheaper per m², but takes weeks to establish. Sod costs more but gives a usable lawn almost immediately.
How big is a standard sod roll?
It varies by supplier — some sell 1 m² rolls, others longer, narrower strips. The 1 m² default is a starting point; adjust it to your nursery's actual size.
What seeding rate should I use?
It depends on the grass type: most common lawns use 25 to 50 g/m². Check the seed bag, which usually states the recommended rate.
Do I need to prepare the soil before planting?
Yes, in both cases. Level it, remove rocks, and loosen the top few centimeters; add compost if the soil is poor. Poorly prepared soil reduces the yield of either method.
How much waste should I allow?
10% covers normal edges and trim on a reasonably regular plot. Increase the margin if your garden has many curves or plant islands.