🇮🇳 Performance Calculator

Gear Ratio Calculator

Calculate your final drive ratio from ring & pinion teeth, and find engine RPM at any cruising speed (km/h) for your tyre size and transmission gear.

Drivetrain

Use 1.00 for top-gear direct drive; enter your gear's ratio for others.

Tyre Size

Format: 195/55R16 - overall diameter computed automatically. Use our Tyre Size calculator to find yours.

Final Drive Ratio

3.73

ring ÷ pinion

RPM at 110 km/h

2,780

Ratio Type

Balanced

km/h per 1,000 RPM

25.2

Tyre Revs/km

450

The gear ratio formula.

Final Drive = Ring Teeth ÷ Pinion Teeth Tyre Diameter (mm) = Rim × 25.4 + 2 × (Width × Aspect / 100) RPM = (km/h × Final × Trans Gear × 1,000,000) ÷ (60π × Tyre Diameter(mm)) 1,000,000 ÷ 60π ≈ 5,305 - the unit constant converting km/h and mm to RPM

Numerically higher ratios (e.g. 4.10) give quicker acceleration and more towing grunt but higher cruising RPM and worse highway mileage. Lower ratios (e.g. 3.08) cruise calmer and more efficiently but feel lazier off the line.

Frequently asked questions.

What does a higher gear ratio do?

A numerically higher final drive (like 4.10 vs 3.55) multiplies torque to the wheels - quicker acceleration and better towing - at the cost of higher highway RPM and lower fuel economy (km/l).

Do bigger tyres change my effective gear ratio?

Yes. Larger-diameter tyres effectively lower your gearing (fewer wheel revolutions per km), reducing acceleration and throwing off your speedometer. Many people re-gear after a big tyre upgrade to compensate.

What gear ratio is best?

It depends on use. Daily drivers favour lower ratios (3.08-3.55) for quiet, efficient cruising; SUVs and performance builds favour higher ratios (3.73-4.56) for grunt and acceleration.