What is the Canola Seed Rate Calculator?
This tool estimates how much canola (oilseed rape) seed you should plant per hectare to reach a target plant stand. Because canola seed size and field losses vary widely, sowing a fixed weight per acre often gives too thin or too thick a stand. Working back from a target plant density gives a far more reliable result. The calculator is universal and works in any country — outputs are given in both kg/ha and lb/acre.
How to use it
Enter four values: the thousand seed weight (TSW) in grams from your seed lot label or a quick bench count, your target plant density in plants per square metre (commonly 40–80 for canola), the expected emergence percentage, and the seedling survival percentage. The calculator returns the seeding rate plus the total seeds you need per square metre.
The formula
First combine the two loss factors into an effective establishment fraction \(E\):
$$E = \frac{\text{Emergence}}{100} \times \frac{\text{Survival}}{100}$$Then convert the target density into a weight of seed, where TSW is the weight of 1000 seeds in grams:
$$\text{Rate}_{kg/ha} = \frac{\text{Target}}{E} \times \frac{\text{TSW}}{1000} \times 10$$The factor of 10 converts grams per square metre to kilograms per hectare (a hectare is 10,000 m², and 1000 g = 1 kg).
Worked example
Suppose TSW = 4.5 g, target = 70 plants/m², emergence = 60% and survival = 100%. Establishment is:
$$E = 0.60 \times 1.00 = 0.60$$Seeds needed per m²:
$$\frac{70}{0.60} = 116.67\ \text{seeds/m}^2$$Seeding rate:
$$116.67 \times \frac{4.5}{1000} \times 10 = 5.25\ \text{kg/ha}$$That is about \(5.25 \times 0.892 \approx 4.68\) lb/acre.
FAQ
What target density should I use? Many agronomists aim for 50–80 plants/m² for canola; check local recommendations for your variety and region.
Where do I find TSW? It is usually printed on the seed bag; otherwise count out 200 seeds, weigh them, and multiply by 5.
What emergence should I assume? Canola field emergence is often only 50–70% of seeds sown, so do not assume 100%.
