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Tractor power for the implement

What engine power the tractor needs to pull the implement at working speed.

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
Implement
Tractor

Draft force comes from the implement's technical sheet or from a test. In soft soil and with wheel slip, efficiency drops; in firm soil, it rises.

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—Required engine power
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Engine power by speed

Engine power in kW for different working speeds, with the force you entered.

Tap the chart to see the values.

Engine power by traction force

Engine power in kW for different required forces, with the speed you entered.

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.

Engine power (cv) by force and speed

Required engine power for combinations of traction force and speed, with the traction efficiency 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

    Enter the traction force the implement requires, in kN, and the working speed, in km/h. Also enter the tractor's traction and transmission efficiency. The calculator estimates the drawbar power and the engine power, in kW and cv.

    Hypothetical example

    Set that requires 15 kN of draft at 6 km/h, with an efficiency of 0.75.

    Drawbar power = 15 × 6 ÷ 3.6 = 25 kW. Motor power = 25 ÷ 0.75 = 33.3 kW, or about 45 cv.

    Precautions

    • For implements driven by the power take-off (PTO), the power is different: add the shaft power to the traction calculation.
    • The rated power of the tractor is the maximum; working at the limit shortens its useful life and fuel use is high.
    • Draft force is the most uncertain value in the calculation: use manufacturer data or a test.

    Method, assumptions, and references

    Equations used

    Drawbar power (kW) = traction force (kN) × speed (km/h) ÷ 3.6
    Engine power (kW) = drawbar power ÷ traction efficiency
    1 kW = 1.36 cv

    Assumptions and limits

    • Draft force is implement data (technical sheet or test); for a plow, it depends on width, depth and soil type.
    • Does not include PTO power for shaft-driven implements; if there is any, add it.
    • Constant efficiency; it varies with soil and wheel slip.

    Standards and technical documents

    • ASABE. ASAE D497.7: Agricultural machinery management data. St. Joseph: ASABE.

    Frequently asked questions

    Why not use the tractor's rated power?

    Rated power is the maximum. The implement uses only part of it, and the margin avoids working at the limit.

    How to estimate the draft force of a plow?

    From the specific soil draft multiplied by the cutting area of each body (width × depth). The plow's technical sheet usually gives this value.