Off-roaders often choose a winch rated at 1.5 times the vehicle’s gross weight. The real pull needed depends on how badly the vehicle is stuck – a car on a paved road rolls easily, while one bogged in mud to the axles needs a pull equal to its own weight. Each layer of rope on the drum also reduces the winch’s pulling power.
How to use the Winch Size Calculator
- Vehicle gross weight
- Ground conditions
- Slope angle
- Extra resistance from damage (e.g. locked wheels)
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the vehicle weight, choose the ground conditions and slope, and add any resistance from damage (for example a locked wheel).
Tips
- Use your own measured figures – fuel economy, speed and prices vary a lot with driving style, traffic, load and season.
- Pick the unit in each field’s menu (miles or kilometres, mpg or L/100 km); the calculator converts everything for you.
- Fill up to the brim twice and divide the distance by the fuel added to measure real fuel economy.
- For vehicle modifications, treat results as a starting point and confirm with the parts maker or a professional mechanic.
Common mistakes to avoid
- Mixing US and imperial (UK) gallons – a UK gallon is about 20% bigger.
- Using the advertised fuel economy instead of real-world figures.
- Forgetting tolls, parking and wear and tear when comparing driving with public transport.
Inputs explained
| Field | What to enter |
|---|---|
| Vehicle gross weight | Units: lb, kg, g, oz |
| Ground conditions | Choose one: Paved road (factor 25), Gravel (5), Wet grass (4), Shingle (3) … |
| Slope angle | Units: ° |
| Extra resistance from damage (e.g. locked wheels) | Units: lb, kg, g, oz |
What each result means
- Rolling / bogging resistance = [Vehicle gross weight]÷[Ground conditions]
- Required line pull = [Rolling ÷ bogging resistance] + [Gradient resistance] + [Extra resistance from damage (e.g. locked wheels)]
- Recommended winch rating = max(1.5×[Required line pull], 1.5×[Vehicle gross weight])
Example values
How the main result changes when Vehicle gross weight changes and everything else stays at the example values above:
| Vehicle gross weight (lb) | Recommended winch rating (lb) |
|---|---|
| 2,500 | 3,750 |
| 3,750 | 5,625 |
| 5,000 | 7,500 |
| 6,250 | 9,375 |
| 7,500 | 11,250 |
| 10,000 | 15,000 |
Formula
Rolling resistance = weight ÷ ground factor (road 25 … bogged to the bonnet 0.33)Gradient resistance = 0 (< 15°), ¼ W (15–30°), ½ W (30–45°), W (> 45°)Required pull = rolling + gradient + damage; recommended winch ≥ 1.5 × required (and ≥ 1.5 × vehicle weight)Worked example
Inputs — Vehicle gross weight: 5,000 lb; Ground conditions: Mud, sand or soft clay (2); Slope angle: 20 °; Extra resistance from damage (e.g. locked wheels): 0 lb.
Results — Rolling / bogging resistance = 2,500 lb; Gradient resistance = 1,250 lb; Required line pull = 3,750 lb; Recommended winch rating = 7,500 lb.
Frequently asked questions
What size winch do I need?
A common rule is at least 1.5 × the vehicle's gross weight – a 5,000 lb truck needs a 7,500 lb winch or larger.
Why does the rating drop as rope winds on?
The drum diameter grows with each layer, reducing pulling force by about 10% per layer.
How can I double my pulling power?
Use a snatch block to make a double-line pull, which roughly doubles the force (at half the speed).
What formula does the Winch Size Calculator use?
Rolling resistance = weight ÷ ground factor (road 25 … bogged to the bonnet 0.33).