What this planner works out
You measure the lawn as one or more areas: rectangles, circles or an area you measured yourself. Beds, paths or a patio inside the lawn are added as areas to leave out, and the planner subtracts them. Then you add what you plan to buy, each one optional:
- Grass seed, either from the seed rate on the label (weight per area) and the pack weight, or from the area one pack covers.
- Turf (sod) rolls, from the roll size: length × width, or the area of one roll. A pallet size is optional.
- Lawn feed, from the area one bag covers per application and the number of applications you plan.
For each product you get the exact quantity, the quantity with your allowance, the packs, rolls or bags to buy, the purchase quantity, the leftover and the cost if you entered a price. Every figure comes from you and the label; nothing is built in.
How the lawn area is measured
- Rectangle: length × width.
- Circle: π × diameter² ÷ 4. A round lawn 4 m across is π × 4 × 4 ÷ 4 = 12.57 m².
- Area you measured: the area as you typed it.
Lawn areas are added up, then the areas left out are subtracted. A lawn of 10 × 8 m and 6 × 5 m with a 2 × 3 m bed and a 4 m² path left out is 80 + 30 − 6 − 4 = 100 m². If the areas left out are as large as the lawn, there is no result until you check them.
Measuring an odd-shaped lawn, step by step
- Sketch the lawn from above and mark the beds, paths, a patio or anything else inside it that will not get seed or turf.
- Split the lawn into rectangles and circles that do not overlap, the same way an L-shaped room is split in how to measure a room. A strip along a curved edge can be a narrow rectangle.
- Measure each part: the length and width of each rectangle, and for a circle the distance across its middle.
- Measure every area to leave out in the same way: beds, paths and the patio.
- Enter the parts and the areas left out, and check that the total looks right against your sketch.
For example, a lawn of 40 × 25 ft with a 15 × 10 ft strip beside it, a round bed 6 ft across and a 3 × 20 ft path:
- Lawn: 40 × 25 + 15 × 10 = 1,000 + 150 = 1,150 ft²
- Left out: the bed π × 6 × 6 ÷ 4 = 28.27 ft² and the path 3 × 20 = 60 ft²
- Net lawn: 1,150 − 28.27 − 60 = 1,061.73 ft²
- Seed at a label rate of 4 lb per 1,000 ft²: 4.25 lb, so 2 packs of 3 lb with 1.75 lb left over
- Or turf in rolls of 10 ft² with a 5 % allowance: 1,114.81 ft², so 112 rolls
Worked example: seed by the label rate
A new lawn of 40 m² and a label rate of 35 g/m² need 40 × 35 = 1,400 g, or 1.4 kg. In 1 kg packs that is 1.4, rounded up to 2 packs, with 600 g left over.
In US units: a lawn of 50 × 30 ft is 1,500 ft². With a 20 × 10 ft patio left out, 1,300 ft² remain. At a label rate of 4 lb per 1,000 ft² that is 1,300 × 4 ÷ 1,000 = 5.2 lb, so 2 packs of 3 lb, with 0.8 lb left over.
Worked example: seed by the coverage per pack
Many bags say what they cover instead of a rate, and often give one figure for a new lawn and a higher one for overseeding. Choose the job and enter the figure for it. A 5,000 ft² lawn and a bag that covers up to 2,800 ft² need 5,000 ÷ 2,800 = 1.79 bags, so 2 bags. If the same bag says 5,600 ft² for overseeding and that is your job, 5,000 ÷ 5,600 = 0.89, so 1 bag.
Worked example: turf rolls and pallets
The 1,300 ft² lawn above with a 5 % allowance is 1,300 × 1.05 = 1,365 ft². Rolls of 2 × 5 ft cover 10 ft² each: 1,365 ÷ 10 = 136.5, so 137 rolls. With 50 rolls on a pallet, that is 2 pallets and 37 loose rolls, or 3 pallets with 13 rolls spare. The planner shows both and never rounds the rolls down; ask your supplier how they sell part pallets.
Turf is cut to order, so running short can mean a second delivery days later. A few spare rolls cost less than a few too few. The planner has no recommended allowance: choose your own with that in mind.
Worked example: feed over two applications
A 12,000 ft² lawn fed twice is 12,000 × 2 = 24,000 ft² of cover. With bags that cover 5,000 ft² per application, 24,000 ÷ 5,000 = 4.8, so 5 bags. The two applications are added up before rounding: rounding each one on its own would give 3 + 3 = 6 bags.
Worked example: two bag sizes
Say the 5,000 ft² bag costs 20 and a 15,000 ft² bag of the same product costs 45. For the 24,000 ft² above, the small bags alone are 5 × 20 = 100 and the large bags alone are 2 × 45 = 90. Mixed, 1 large bag and 2 small bags cover 25,000 ft² for 85. The planner shows this as the lowest total among the sizes and prices you entered, next to each single size, so you can also choose fewer bags instead. It compares sizes of one product only.
Allowance, already bought and the shopping list
The project allowance is your own extra on top of the exact quantity; 0 means none. A product can have its own, for example 5 % for turf and none for feed. It is added before the packs are rounded up, as how pack rounding works explains. Enter what you already have under “Already bought”, and the shopping list shows what is still to buy. Download the list as CSV, download the plan as a PDF or print it, and keep a JSON backup of your projects. Projects stay in your browser; they are saved on this device only if you tick “Keep my projects on this device”.
Common mistakes
- Using the overseeding figure for a new lawn. The bag in the coverage example covers 5,600 ft² when you overseed but 2,800 ft² on a new lawn. A new 5,000 ft² lawn planned with the overseeding figure gets 1 bag instead of 2: half the seed its label asks for.
- Typing the radius of a circle as its diameter. The planner asks for the distance across. The round lawn 4 m across, typed as 2 m, comes to 3.14 m² instead of 12.57 m²: a quarter of the real area.
- Leaving the beds in. If the bed and the path are not left out, the lawn in the step-by-step example is 1,150 ft² instead of 1,061.73 ft², and the turf order grows from 112 to 121 rolls.
Limits
This is a quantity estimate from your own measurements and the figures on the label. It does not choose a grass species, a seed rate or a feed, and gives no advice on soil, timing, watering or weather. Feed is planned from the coverage on the bag only, never from the fertilizer analysis. Apply feed at the rate on the label, and follow the label and local rules; some areas restrict lawn fertilizer, for example near water. For topsoil or top-dressing under the lawn, use the mulch, soil and gravel calculator.