Winch Size Calculator — Required Pull Capacity
Enter your vehicle weight, slope angle, terrain type and a safety factor to find the minimum winch pull rating you need for safe recovery. The breakdown shows how much of the requirement comes from slope gravity, terrain friction, and the safety margin.
Weight unit
kg
°
Terrain type
Includes slope force, terrain friction, and the safety factor — choose a winch rated at or above this value
- 1
Slope (gravity) force
2,000 × sin(20°) = 684 - 2
Terrain friction force
2,000 × 0.15 × cos(20°) = 282 - 3
Total raw pull
684 + 282 = 966 - 4
Required capacity (× safety factor)
966 × 1.5 = 1,449Industry standard minimum is 1.5× the raw pull to account for dynamic loads and cable friction.
How does this calculator work?
Required winch capacity = (W × sin θ + μ × W × cos θ) × safety_factor, where W is vehicle weight, θ is slope angle, and μ is the terrain friction coefficient (0.05 for paved, up to 0.60 for deep mud). Enter weight, slope, terrain, and safety factor; the calculator outputs the minimum rated pull capacity in kg and lb.
Formula
How this is calculated
When a vehicle is stuck or needs to be recovered on an incline, the winch must overcome two forces: the component of gravity pulling the vehicle down the slope (W × sin θ, where W is the vehicle weight and θ is the slope angle) and the rolling/terrain resistance opposing motion (μ × W × cos θ, where μ is the terrain friction coefficient). The sum of these forces is the minimum pull force needed in ideal conditions.
In practice, wire rope experiences added friction over fairleads and pulleys, loads shift, and conditions worsen mid-recovery. For this reason the industry standard is to multiply the raw pull requirement by a safety factor of 1.5× at minimum — meaning the winch's rated line pull should be at least 1.5 times the computed force. More demanding recoveries (deep mud, multiple bends, damaged terrain) may warrant 2× or higher.
Terrain resistance coefficients used here are representative values: paved flat (μ ≈ 0.05), grass/gravel (μ ≈ 0.10), dirt track (μ ≈ 0.15), soft sand (μ ≈ 0.25), moderate mud (μ ≈ 0.40), deep mud (μ ≈ 0.60). These are estimates drawn from automotive engineering references and should be treated as planning guides. Always oversize a winch rather than undersize it — operating near the rated limit heats the motor and reduces cable life.
Frequently asked questions
A 1.5× factor accounts for dynamic loads (jerking, cable stretch rebound), increased friction from cable layers on the drum as it winds in, and practical uncertainties in terrain conditions. On especially difficult recoveries — multiple pulley redirections, deep bog, heavy load — professionals often specify 2× or more.
A single snatch block roughly doubles the mechanical advantage, allowing a smaller-rated winch to handle a heavier pull — but the anchor and mounting must be rated for the combined load. This calculator gives the direct-pull requirement; if you plan to rig a pulley, you can select a winch rated at approximately half the calculated value (adjust for pulley efficiency loss of ~10–15 %).
Rated line pull is typically specified with only one layer of cable on the drum. As you wind in cable, additional layers reduce pull capacity because of the increased drum radius — some winches lose 25–40 % of rated capacity by the inner layers. Factor this in if you expect to spool most of the cable.
Also known as
TG we-Calculate Editorial Team. (2026). Winch Size Calculator — Required Pull Capacity [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/winch-size-calculator
TG we-Calculate Editorial Team. "Winch Size Calculator — Required Pull Capacity." TG we-Calculate. 2026. https://we-calculate.com/calculator/winch-size-calculator.
TG we-Calculate Editorial Team, "Winch Size Calculator — Required Pull Capacity," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/winch-size-calculator
@misc{wecalculate_winch_size_calculator, title = {Winch Size Calculator — Required Pull Capacity}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/winch-size-calculator}}, year = {2026}, note = {TG we-Calculate} }
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