Whether you’re righting a rolled vehicle or dragging one out of mud, the pull required depends on very different physics, this calculator handles both scenarios and applies an appropriate safety margin to the result.
How to use this winch size calculator
- Choose what you’re doing: Right a Rolled-Over Vehicle, or Drag or Recover a Stuck Load.
- Select a Vehicle Type for a quick-fill weight, or enter a custom weight.
- For righting: enter the Centre of Gravity Offset and Vehicle Height.
- For dragging: enter Damaged/Stuck Wheels, Surface Condition, and Slope Angle.
- Select your Safety Margin and read the Minimum Winch Rating.
Righting a rolled vehicle
Righting a rolled vehicle needs a pull strong enough to lever the vehicle back onto its wheels, using its centre of gravity as a pivot point. The closer the anchor height is to the vehicle’s own height, the less force is needed, which is why this calculator asks for both the centre of gravity offset (horizontal distance from the pivot edge to the centre of gravity) and the vehicle’s overall height (the lever arm the winch line pulls against).
Righting Pull ≈ (Vehicle Weight × Centre of Gravity Offset) ÷ Vehicle Height
Dragging or recovering a stuck load
Dragging a stuck load combines three separate resistances: damaged-wheel drag (how many of the vehicle’s wheels are stuck or non-rolling), rolling resistance from the surface condition, and gradient resistance if you’re pulling up or down a slope. Surface conditions range from a factor of 25 for hard road down to as low as 0.33 for a vehicle bogged to the bonnet, reflecting how dramatically ground conditions affect the pull required.
Recovery Pull ≈ (Vehicle Weight ÷ Ground Factor) × (Damaged Wheels ÷ Total Wheels adjustment) ± Gradient Resistance (from Slope Angle)
Why the safety margin matters so much here
A common industry rule of thumb is to size the winch at 1.5× the pull you calculate, since surface conditions vary in practice, and the first few seconds of a pull need extra force to overcome static friction, higher than the steady-state pull needed once the load is already moving. This calculator lets you choose no margin, a standard 1.33×, the recommended 1.5×, or an extra-cautious 2× margin depending on how much buffer you want.
Frequently asked questions
Why does anchor height matter when righting a rolled vehicle?
The closer the anchor point’s height is to the vehicle’s own height, the more mechanical advantage the lever arm provides, meaning less winch force is needed to lever the vehicle back onto its wheels.
Why is a safety margin recommended on top of the calculated pull?
Surface conditions vary in practice, and the initial moment of a pull needs extra force to overcome static friction, higher than the steady pull needed once the load starts moving. A 1.5× safety margin is the common industry recommendation to account for this.
Why does ground condition change the required pull so dramatically?
Rolling resistance varies enormously by surface, a hard road offers very little resistance (factor 25) while a vehicle bogged to the bonnet in mud offers extreme resistance (factor as low as 0.33), directly multiplying the pull force needed for recovery.
