A quality 10 kg bag of granular lawn fertiliser costs around $70 in Australia. At a typical 25 g per m², that bag feeds about 400 m², so fertilising an average 100 m² backyard costs roughly $18 per feed, or about $50–$55 a year with three feeds. The calculator below works it out for your lawn size and fertiliser, including how many kilograms to spread each time.
Lawn Fertiliser Calculator
How much fertiliser your lawn needs, and what it costs per feed and per year
Rates are from Australian product labels. Spreader settings differ by brand, so use the setting printed on your bag or calibrate on a measured 10 m² strip. Water in straight after spreading, and don’t fertilise when it’s over 30°C.
How much fertiliser per square metre?
Most granular lawn fertilisers in Australia are applied at 10–30 g per m². The exact figure is on the bag, and it varies with how concentrated the product is:
| Product | NPK | Label rate | Per 100 m² |
|---|---|---|---|
| Lawn Solutions Premium (buffalo, couch, kikuyu) | 16-0.7-4 | 25 g/m² | 2.5 kg |
| Lawn Solutions Premium (zoysia) | 16-0.7-4 | 15 g/m² | 1.5 kg |
| Lawn Solutions Premium (Sir Grange) | 16-0.7-4 | 10 g/m² | 1 kg |
| Scotts Lawn Builder All Lawn Types | 32-0-8 | 14 g/m² | 1.4 kg |
| Amgrow Buffalo Lawn Food | – | 25 g/m² | 2.5 kg |
| Amgrow Granular Lawn Food | – | 30 g/m² | 3 kg |
Higher-nitrogen products such as Scotts at 32% N go on at a lower rate, so a bag covers more ground. Per feed, most labels deliver about 4–5 g of nitrogen per m². If your fertiliser isn’t listed, choose “Other” in the calculator and enter the first number of its NPK. It works out a rate that delivers about 4 g of nitrogen per m². Use the bag’s label rate if it gives one.
Zoysia and Sir Grange need much less than buffalo or couch. Over-feeding them causes more thatch and mowing, not a better lawn.
What lawn fertiliser costs
The bag price matters less than the cost per feed, because concentrated products cover more ground per kilogram. As a guide:
- Premium granular, 10 kg: around $70, about $7 a kilogram (Lawn Solutions Premium at Bunnings, Oct 2026)
- Small 2.5–4 kg bags: handy for small lawns, but usually dearer per kilogram
- Liquid hose-on fertilisers: quick and easy, but they cost more per m² and don’t last as long as slow-release granules
Example costs (Lawn Solutions Premium at 25 g/m², $71 per 10 kg)
| Lawn size | Per feed | Cost per feed | Per year (3 feeds) |
|---|---|---|---|
| 50 m² | 1.25 kg | $8.88 | $26.63 |
| 100 m² | 2.5 kg | $17.75 | $53.25 |
| 200 m² | 5 kg | $35.50 | $106.50 |
| 400 m² | 10 kg | $71.00 | $213.00 |
A lawn-care contractor will charge for labour and travel on top of the product. Doing it yourself with a cheap push spreader pays for itself within a season or two.
When and how often to fertilise
- Spring: the most important feed, given as warm-season grasses wake up.
- Summer: an optional light feed for lawns that get a lot of use.
- Autumn: helps the lawn hold its colour and go into winter strong.
- Winter: generally skip it for warm-season grasses, because they’re dormant.
Two feeds a year (spring and autumn) keeps most home lawns healthy, and three gives a lusher look.
Spreading tips
- Use a spreader. Throwing by hand causes stripes and burnt patches.
- Split it in two. Set the spreader to half rate, go over the lawn once lengthways and once crossways.
- Calibrate if there’s no setting for your spreader. Mark out 10 m², spread the right amount for that area (for example 250 g at 25 g/m²), and adjust until it runs out just as you finish.
- Water it in straight away to wash the granules off the leaves. Avoid spreading in heat over 30°C.
- New turf: wait until after the first mow, then use half rate.
Frequently asked questions
How much is lawn fertiliser in Australia?
A 10 kg bag of premium granular lawn fertiliser is about $70. Smaller bags cost less but usually more per kilogram. For a 100 m² lawn, expect around $18 per feed.
How much fertiliser do I need for 100m² of lawn?
Usually 1.4–3 kg, depending on the product. At 25 g/m² it’s 2.5 kg.
How much lawn fertiliser per square metre?
Typically 10–30 g per m². Follow the rate on your bag.
How many square metres does a 10kg bag of fertiliser cover?
About 400 m² at 25 g/m², or about 700 m² at 14 g/m².
How often should I fertilise my lawn?
Two to three times a year for most Australian lawns: spring, autumn and optionally summer.
Do I need to water in lawn fertiliser?
Yes, straight after spreading, so the granules don’t burn the leaves.
What spreader setting should I use?
Use the setting printed on the fertiliser bag for your spreader brand. If there isn’t one, calibrate on a measured 10 m² area.
