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Lawn Feed Calculator — How Much Lawn Feed Do I Need?
Calculate the right amount of lawn feed, weed and feed, or seasonal fertiliser for your lawn area. UK application rates.
Length of your lawn
Width of your lawn
Enter your supplier price for a cost estimate
How We Calculate This
Our lawn feed calculator multiplies your lawn area by the standard application rate to work out how much product you need, then converts this to the number of boxes or bags required.
The formula
Lawn area = Length × Width
Product needed (g) = Area (m²) × Application rate (g/m²)
Boxes = Area ÷ Box coverage (rounded up)
Application rates
- Spring feed: ~35 g/m² (high nitrogen N:P:K)
- Summer feed: ~35 g/m² (balanced N:P:K)
- Autumn feed: ~35 g/m² (high potassium N:P:K)
- Weed & Feed: ~35 g/m² (combined herbicide + feed)
Standard box sizes
- Small box: 3.5 kg — covers approx. 100 m²
- Large box: 7 kg — covers approx. 200 m²
Always check the specific product instructions as rates and coverage may vary between manufacturers. Our calculator uses 35 g/m² — the most common UK branded rate (Westland SafeLawn, Miracle-Gro EverGreen Spring & Summer and Autumn all apply at 35 g/m² by hand or spreader). UK guidance gives a 25–35 g/m² range, so confirm against your product label before ordering.
Frequently Asked Questions
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Last updated: February 2026
Verified against UK standards · estimates only, confirm with your supplier.