What this calculator does
The standard guidance is a winch rated at 1.5 times the vehicle gross weight. A 5,000 lb vehicle therefore wants a 7,500 lb winch, which in practice means buying the 8,000 lb model since that is what is sold.
The factor exists because the rated capacity is measured on the first layer of rope on the drum, and pulling capacity falls as rope stacks up. By the outer layer a winch may deliver only 60 to 70% of its rating, so a winch sized exactly to the vehicle weight will struggle precisely when it is fully spooled.
The formula
The vehicle gross weight is multiplied by the safety factor to give a recommended capacity. Use the gross vehicle weight rating rather than the kerb weight, since a loaded vehicle is what actually needs recovering, and add the weight of anything being towed before applying the factor.
| Term | Meaning |
|---|---|
| GVWR | Gross vehicle weight rating: the maximum loaded weight, which is the figure to size from. |
| Safety factor | A multiplier over the vehicle weight, conventionally 1.5. |
| First layer rating | Winch capacity is quoted for the innermost layer of rope, where the drum diameter is smallest and pull is greatest. |
| Snatch block | A pulley that doubles the effective pull by routing the line back to the vehicle, at the cost of halving line speed. |
The inputs explained
| Field | What to enter |
|---|---|
| Vehicle weight (GVWR) (lb) | Vehicle gross weight in pounds. Use the GVWR from the door placard rather than the kerb weight, and add any trailer or load. |
| Safety factor | Safety factor. 1.5 is the common recommendation. Use more for heavy mud, steep recovery or frequent winching. |
When to use it
Buying a winch for a vehicle
Winches are sold in fixed capacity steps, and the calculation identifies which step is the minimum sensible one.
Checking an existing winch
A winch inherited with a vehicle may have been sized for a lighter build, which matters once the vehicle is loaded.
Sizing for a trailer or heavy load
The factor applies to the whole weight being moved, so a towed load changes the answer substantially.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What winch capacity does each vehicle weight need?
A range of vehicle weights at the standard factor.
| Vehicle weight (GVWR) | Recommended winch capacity | In kilograms | Vehicle weight |
|---|---|---|---|
| 4,000 lb | 6,000 lb | 2,722 kg | 4,000 lb |
| 5,000 lb | 7,500 lb | 3,402 kg | 5,000 lb |
| 6,000 lb | 9,000 lb | 4,082 kg | 6,000 lb |
| 8,000 lb | 12,000 lb | 5,443 kg | 8,000 lb |
Questions
What size winch do I need?
At least 1.5 times your vehicle gross weight. For a 5,000 lb vehicle that is 7,500 lb, which means buying an 8,000 lb winch. Going larger costs more and adds weight to the front axle, but undersizing is the more common and more expensive mistake.
Why 1.5 times and not exactly the vehicle weight?
Because rated capacity applies only to the first layer of rope on the drum. As rope stacks up the effective drum diameter grows and pull drops, often to 60 or 70% of the rating on the outer layer. The factor covers that, plus the extra resistance of mud, a slope or a partly buried wheel.
Does a snatch block change the size I need?
It roughly doubles the effective pull, so a snatch block can rescue an undersized winch in a difficult recovery. It is not a substitute for correct sizing, since it halves line speed and needs a suitable anchor point, but it is worth carrying.
Should I use kerb weight or GVWR?
GVWR. A vehicle needing recovery is usually loaded, often with fuel, gear and passengers, and may be partly stuck in mud or sand that adds considerable resistance. Sizing from the empty weight understates the job.
For tire sizing on the same vehicle, see the tire size calculator. For running costs, see the cost per mile calculator.