Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.

Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.

Automotive Calculators

Overall Gear Ratio Calculator

2026-09-27 6 min

Total reduction from transmission gear × final drive (× transfer case) — the number behind RPM and wheel torque.

Overall Ratio: 5.59 :1
Torque Multiplication: 5.59 ×; Before efficiency losses

Calculator

Transmission Gear(:1)

Final Drive(:1)

Transfer Case(:1) Help

1.00 in high range

Results update live as you type

Live statistics

Overall Ratio

5.59 :1

Torque Multiplication

5.59 ×

Before efficiency losses

Results

Optimal

Overall Ratio

5.59:1

Torque Multiplication

5.59×

Before efficiency losses

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

Visualizations

Results overview

5.6Overall Ratio

5.6Torque Multiplication

Overall Ratio vs. Transmission Gear

Overall Ratio

5.6:1

120

Formula

Reductions in series multiply — every ratio the power flows through compounds into one total.

Overall = transmission × final × transfer

Variables

Symbol	Name	Unit	Description
trans	Gear ratio	:1	Selected transmission gear
final	Final drive	:1	Axle ratio
transfer	Transfer case	:1	1.00 high / ~2–4 low

Explanation

First gear overall (e.g. 3 × 3.73 ≈ 11) vs overdrive (≈ 2) shows why launch torque dwarfs cruise torque.

Step-by-Step Calculation

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

Step 1

Record the inputs.

Transmission Gear:1.5 :1

Final Drive:3.73 :1

Transfer Case:1 :1

Result: 3 inputs ready

Step 2

Apply the formula.

Overall = transmission × final × transfer

Result: Primary result = 5.59 :1

Step 3

Read every derived output.

Overall Ratio:5.59 :1

Torque Multiplication:5.59 ×

Result: Overall Ratio = 5.59 :1

Final Answer

5.59

Worked Examples

See how the calculator works with different scenarios.

Scenario

1.50 gear × 3.73 axle.

Inputs

Trans:1.50

Final:3.73

Transfer:1.00

Calculation

1.50 × 3.73 = 5.60

Result

5.60:1 overall.

Interpretation

Each lb-ft at the crank becomes ~5.6 at the wheels (minus loss).

Understanding Your Result

Your Result: Overall Ratio: 5.59 :1

What This Means

Combined torque multiplication from crankshaft to wheels in the selected gear.

Why It Matters

Overall ratio feeds wheel torque, RPM-at-speed and shift-point math directly.

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

Gears in series multiply: the overall ratio is the whole powertrain reduced to one number.

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)

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

Practical Tips

•Start from the default values — they describe a typical combination
•Use the sensitivity chart to see which input moves the result most
•Keep units consistent (all inches or all mm, never mixed)

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.

Do I include the transfer case?

Yes in 4WD: multiply by the range ratio (1.00 high, ~2.72 low are common).

What overall ratio launches hardest?

First gear overall (often 10–13:1) — traction, not torque, becomes the limit.

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Related Guides

Deepen your understanding with these educational resources.

Automotive Guides

Build planning, measurement protocol and validation how-tos

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.

EPA — FuelEconomy.gov DOE — Fuel-Efficient Driving Tips NHTSA — Driving Safety & Efficiency SAE International — Fuel Economy Standards Consumer Reports — MPG Truth IRS — Standard Mileage Rates

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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Page Information

Last Updated:

2026-09-27

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.