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Exchange ratio: bags per tonne of fertilizer

See how many bags of grain buy one tonne of fertilizer. The lower the number, the cheaper the fertilizer relative to the grain.

Pre-sizing and estimating tool: the results do not replace a design, calculation, or report signed by a qualified professional, nor verification against the applicable standards.

Preliminary estimateRevision 12/11/2026
Prices

Use cash prices from your local market. The ratio shows how many bags buy one tonne of fertilizer.

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—Grain bags per tonne of fertilizer
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Exchange ratio by fertilizer price

Bags per tonne when the fertilizer price rises or falls; the highlighted bar is the price you entered.

Tap the chart to see the values.

Exchange ratio by bag price

Bags per tonne at each grain price, with the fertilizer price you entered; the dot is your price.

Tap the chart to see the values.

What if the data changes?

Drag the controls to simulate data different from what you entered (from 30% less to 30% more) and watch the result change instantly.

Tap the chart to see the values.

Bags per tonne by fertilizer and bag price

Grain bags needed to buy one tonne of fertilizer, for combinations of fertilizer and bag prices around the values you entered.

Step by step with your numbers

The calculation done in steps, with the values you entered.

    The calculation memo gathers this page's inputs, results, equations, assumptions, and references, with fields for project, responsible person, and review. The full report also includes the charts and interpretations, in color. In the print window, choose Save as PDF.

    How to use the exchange ratio

    Enter the fertilizer price per tonne and the grain bag price in your market. The calculator shows how many bags buy a tonne of fertilizer and how much fertilizer one bag pays for.

    Worked example

    Fertilizer at R$ 3,000/t and soybeans at R$ 120/bag.

    Ratio = 3,000 ÷ 120 = 25 bags per tonne. One bag buys 120 ÷ 3,000 × 1,000 = 40 kg of fertilizer.

    How to interpret

    • Compare the number with the same month in previous years, not with a fixed value.
    • If the ratio worsens, review the dose with the soil analysis and the recommendation before cutting fertilization.
    • For the fertilizer cost per hectare, use the lowest-cost NPK formulation.

    Method, assumptions, and references

    Equations used

    Exchange ratio (bags/t) = fertilizer price (R$/t) ÷ bag price (R$/60 kg bag)
    Fertilizer bought per bag (kg) = Bag price ÷ Fertilizer price (R$/kg) = Bag price × 1,000 ÷ Fertilizer price (R$/t)

    Assumptions and limits

    • Cash prices in the same market, excluding freight, volume discounts and grain grading differences.
    • The exchange ratio measures purchasing power in grain, not the final cost of the input on the farm.

    Standards and technical documents

    • CNA. Inputs: periodic reports on prices and exchange ratios in the field (periodic publication; see the latest edition).

    Frequently asked questions

    Is the exchange ratio the same as the price in reais?

    No. It measures how many bags of grain you need to sell to buy a tonne of fertilizer. This puts the effect of grain and fertilizer prices into a single measure.

    What is a good exchange ratio?

    There is no fixed number. Compare with your region's historical average and with last year's: the more bags per tonne, the more grain you need to sell to buy the same fertilizer.

    Why does the number change so much from year to year?

    Because fertilizer and grain prices change at different rates. In years when fertilizer rises more than grain, the ratio gets worse.

    Does this calculator tell me whether I should buy fertilizer now?

    No. It shows the purchasing power of grain against fertilizer. The buying decision also depends on stock, payment terms, and the technical recommendation.