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Seed Rate Calculator

Works out how much seed to sow to end up with the plant population you want.

The plants you want standing, from your agronomist or seed supplier for this crop and sowing date.

g

On the seed label or certificate. Otherwise weigh 1,000 seeds.

%

On the seed label.

%

The share of germinating seeds that become plants. Falls with a poor seedbed or late sowing. Use your own records if you have them.

Seed rate
— kg/ha

Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.

Seed rate — lb/acre
Seeds to sow — per m²
Seed for the whole area —
Bags —

The formula

seeds per m² = target plants per m² ÷ (germination × establishment) kg/ha = seeds per m² × thousand seed weight (g) ÷ 100

Dividing by 100 turns grams per square metre per thousand seeds into kilograms per hectare.

What to watch out for

Seed lots differ in size, so setting the drill by plants wanted rather than a fixed weight per hectare stops large-seeded lots being under-sown. Do a calibration test on the drill, as seed flow differs by lot.

Frequently Asked Questions

What is thousand seed weight?

The weight in grams of 1,000 seeds. It varies by variety and season, so use the figure for your own lot.

How much seed for 250 plants per m²?

At a 45 g thousand seed weight, 95% germination and 80% establishment, 148.0 kg/ha.

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