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Winch Pull Calculator

2026-09-27 6 min

Required line pull for vehicle weight on a slope with mire resistance, plus a rigging margin.

Required Pull
3549 lb
With 25% Margin
4436 lb

Calculator

Vehicle Weight(lb)
lb
Slope Angle(deg) Help
deg

Uphill grade angle

Mire Coefficient Help

Rolling 0.05, mud ~0.5

Results update live as you type

Live statistics

Required Pull

3549 lb

With 25% Margin

4436 lb

Results

Optimal

Required Pull

3549lb

With 25% Margin

4436lb

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

3,549Required Pull
4,436With 25% Margin

Required Pull vs. Vehicle Weight

Required Pull

3,549lb
020,000

Formula

Adds the downhill weight component to mire drag on the slope, then pads for snatch and friction scatter.

Pull = W x (sin s + mire x cos s); with margin = pull x 1.25

Alternative Form

Grade term climbs with slope; mire term dominates in deep mud

Variables

SymbolNameUnitDescription
sSlope angledegConverted to radians for sin/cos
mMire coefficient0.05 rolling, 0.2 sand, 0.4-0.5 mud

Explanation

On flat mud the mire term rules; on steep rock the grade term rules — this covers both at once.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

Vehicle Weight:5500 lb
Slope Angle:15 deg
Mire Coefficient:0.4
Result: 3 inputs ready
Step 2

Apply the formula.

Pull = W x (sin s + mire x cos s); with margin = pull x 1.25
Result: Primary result = 3549 lb
Step 3

Read every derived output.

Required Pull:3549 lb
With 25% Margin:4436 lb
Result: Required Pull = 3549 lb
Final Answer
3549

Worked Examples

See how the calculator works with different scenarios.

Scenario

Mired rig on a moderate uphill.

Inputs

Weight:5,500 lb
Slope:15 deg
Mire:0.4

Calculation

Pull = 5,500 x (0.259 + 0.386) = 3,549 lb; margin = 4,436 lb

Result

Need ~4,400 lb of line pull.

Interpretation

A single-line 8,000-lb winch handles it; deep mud would not.

Understanding Your Result

Your Result: Required Pull: 3549 lb

Typical range: Flat rolling ~500 lb; muddy flat ~2,500 lb; muddy grade 4,000-8,000 lb.

What This Means

The steady pull the winch must sustain to move the vehicle.

Why It Matters

Separates recoverable single-line pulls from double-line jobs before you rig.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

  • •Double-check units on every input before trusting the result
  • •Compare against the worked example below to sanity-check magnitude
  • •Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

Stuck-vehicle pull is grade load plus ground drag.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

  1. Fill to first click at the same pump, record the odometer (Tank 0).
  2. Drive normally for 2–3 tanks; always refill to first click at the same pump.
  3. MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
  4. Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
  5. Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

  • •Double mire estimate in rutted clay
  • •Add 25% before comparing to winch rating
  • •Rig a snatch block when pull exceeds 60% of rating

Common Mistakes

Mixing units (inches with mm, psi with kPa)
Convert every input to the unit shown on its field before calculating.
Trusting a single output blindly
Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.
Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.
No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

What mire value should I use?
Hard ground 0.05, sand 0.2, soft mud 0.4-0.5. When unsure, use 0.5 — mire is the dominant term.
Does slope really matter?
Yes — a 15-degree grade alone adds ~26% of vehicle weight before any mud drag.

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG
Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km
Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe
Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE
Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance
Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag
Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling
Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II
On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

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