HesapHanem

Lawn Fertilizer Calculator

Find how much fertilizer you need.

Result

36.00 kg
2

How it is calculated

You give the lawn area in square metres, the application rate in grams of product per square metre and the bag size in kilograms. The tool multiplies area by rate and converts grams to kilograms: kg = area × rate ÷ 1000. It then divides by the bag size and rounds up to whole bags: bags = ceil(kg ÷ bag size), since you cannot buy part of a bag. If the rate or the bag size is left empty or at zero, the tool uses 30 g/m² and 25 kg. The rate is for the finished product, not for nitrogen alone, so take it from the label of your fertilizer and do not convert it by the nitrogen percentage. The calculator does not know your grass type, soil or season.

Worked example

A lawn of 1,200 m², a label rate of 30 g/m² and 25 kg bags. Fertilizer needed = 1,200 × 30 = 36,000 g, which is 36.00 kg. Bags = 36 ÷ 25 = 1.44, which rounds up to 2 bags. You will have 14 kg left over, which is useful for a second application or patching bare areas.

Try this example →

Common mistakes

  • Entering the lawn area in square feet or acres. The field is in square metres; 1,000 square feet is about 93 m².
  • Entering the label's nitrogen percentage or kilograms per hectare as the rate. The rate is grams of product per square metre, so 300 kg per hectare is 30 g/m².
  • Measuring the whole property rather than just the lawn. Paths, beds, patios and the house footprint should be taken out of the area.
  • Reading the bag count as the exact amount to spread. It is rounded up, so the real need can be well below the number of bags bought.
  • Spreading the full amount in one pass. The tool gives the total, but many labels split it into two light passes at right angles for even coverage.

About this calculator

This calculator works out how much fertilizer a lawn needs, converting your lawn's area in square meters and the product rate you want in grams per square meter into the kilograms to spread and the number of bags to buy. Blank rate or bag size default to 30 g/m² and 25 kg bags.

Homeowners use it before every feeding to avoid over-application, which can burn grass and run off into waterways, or under-application, which wastes the trip and leaves the lawn under-fed. Lawn care companies use the same math when bagging product for a specific yard size.

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Comments (1)

  • Editorial team

    Bags round up, so the bag size you type changes how much is left over. For 1,200 square metres at 30 g/m², that is 36 kg: two 25 kg bags leave 14 kg, while 10 kg bags need four and leave only 4 kg. Try your local pack sizes before you buy. Measure only the grass itself. Do you work in square feet or acres and want those units added here?

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