Calculate how much lawn or vegetable seed you need for a given area.
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Use this calculator to turn the sowing rate on a seed bag into the mass of seed needed for a lawn, patch, or allotment. The same arithmetic applies to grass seed and vegetable seed when the bag rate is in grams per square metre.
The calculation is: seed mass = area × rate. Area can be entered in square metres (m²) or square feet (ft²); square feet are converted to square metres before multiplying. The rate is always in grams per square metre (g/m²). Seed mass is shown in grams (g), ounces (oz), or pounds (lb).
A new lawn is often sown at about 25–50 g/m²; overseeding uses less. This is the bag rate only: it does not add a waste margin, and it does not convert from seeds per packet unless you have already turned that into g/m².
Area: The patch you will sow, in m² or ft².
Rate (g/m²): The bag rate in grams per square metre.
Seed: Total mass of seed needed for the entered area.
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