Formula
Seed in grams is the area times the sowing rate.
Boxes are that weight divided by the grams in one box, rounded up.
Worked example
40 m² at 30 g/m² is 1200 g (1.20 kg).
At 1000 g a box that is 1.2 boxes, rounded up to 2.
Assumptions
New lawn starts at 30 g per square metre. Overseeding starts at 15 g per square metre. Both are labels to check, not a variety recommendation.
The box starts at 1 kg.
Checked
Checked 10 November 2026. Bunnings lists Garden Basics lawn seed in 1 kg bags. The 30 g/m² and 15 g/m² rates were not those box rates. A Munns 1.1 kg kikuyu bag prints its own coverage, which is different.