What Is a 1 to 5 Gear Ratio?

A 1 to 5 gear ratio usually means the output turns five times for every single turn of the input—so speed increases fivefold while torque drops to one-fifth. However, some engineers use ratio notation differently and might mean a fivefold reduction instead. To avoid confusion, state whether you mean a “speed increase (overdrive)” or a “reduction.”

Defining the Ratio

Gear ratio describes how rotational speed and torque change between an input and an output. Unfortunately, notation varies by industry and context. In speed terms, “1:5” is typically read as input:output speed, so one input revolution yields five output revolutions. In reduction terms, many designers prefer to say “5:1 reduction” for the opposite case—output turns five times slower than input while torque multiplies by five.

Two Common Conventions

When people say “1 to 5,” they may be referencing different, equally common conventions. Here’s how to decode them.

• Speed convention (input:output speed): 1:5 means the output spins five times for each input turn (speed increases by 5x, torque decreases by 5x). This is often called an overdrive.
• Reduction convention (torque/driven emphasis): Many practitioners would describe a fivefold slowdown as “5:1 reduction.” Sometimes people casually say “1:5” to describe the tooth-count ratio of a small driver to a large driven gear, but the standard phrasing is “5:1 reduction.”

The safest practice is to specify “1:5 speed increase (overdrive)” or “5:1 reduction,” rather than using a bare ratio that can be read either way.

What It Means for Speed and Torque

For simple external gear pairs, speed and torque trade off inversely. The output speed divided by input speed equals the input gear teeth divided by the output gear teeth. Conversely, the output torque divided by input torque equals the output gear teeth divided by the input gear teeth, ignoring losses. External gear pairs also reverse rotation direction; internal gear pairs do not.

Worked Examples

The following examples show how a “1 to 5” relationship appears in real setups and how to compute the outcomes.

1. Reduction example (commonly called 5:1 reduction): A 12‑tooth gear driving a 60‑tooth gear yields an output speed that is 12/60 = 1/5 of the input. Torque ideally multiplies by five. Many would call this a “5:1 reduction,” even though the speed ratio is 1:5.
2. Overdrive example (1:5 speed increase): A 60‑tooth gear driving a 12‑tooth gear yields an output speed that is 60/12 = 5 times the input. Torque ideally drops to one‑fifth. This aligns with “1 input turn gives 5 output turns.”
3. Belts or chains: Replace “tooth count” with pulley or sprocket diameter (or effective pitch diameter). The speed ratio equals driver diameter divided by driven diameter; torque ratio is the inverse.

Real systems have friction and inefficiency, so multiply ideal torque by efficiency (for gears, often 90–98% per mesh; for belts/chains, typically a bit lower).

How to Achieve a 1:5 Relationship in Practice

Engineers can realize a 1:5 relationship in one stage or across multiple stages, depending on space, load, and efficiency requirements.

• Single-stage gears: Choose tooth counts where input teeth / output teeth = 1/5 (for reduction) or 5/1 (for overdrive). Example: 12T to 60T (reduction) or 60T to 12T (overdrive), using the same module/DP and pressure angle.
• Belts/chains: Use pulley or sprocket diameters in a 1:5 or 5:1 ratio, ensuring proper center distance and wrap.
• Compound trains: Multiply stages to reach 1:5 (e.g., 1:√5 × 1:√5 ≈ 1:5). This reduces extreme tooth-size differences per stage, easing strength and packaging.
• Planetary gearboxes: Select a catalog unit with overall 5:1 reduction for a robust, compact solution; for a 1:5 speed increase, flip which side is driven if the design allows.

When sizing, verify allowable torque, radial loads, and shaft speeds. Check lubrication, alignment, and backlash targets before finalizing the design.

Where You’ll Encounter It

A 1:5 relationship appears across vehicles, machinery, and hobby projects, either as a speed increase or a reduction depending on the need.

• Robotics and automation: 5:1 reductions to boost joint torque while keeping speed reasonable.
• Vehicles and drivetrains: Overdrive pairs or accessory drives may use step-up ratios near 1:5 to spin pumps, blowers, or generators faster than the crank speed.
• Bicycles and e-mobility: Chainring-to-cog combinations can produce step-ups or reductions in the same spirit, though typical bike ratios are often between about 0.7:1 and 4:1.
• Test rigs and lab equipment: Step-up gearing to achieve higher spindle speeds from modest motor RPM.

The same numeric ratio can serve different goals: step-up for speed-critical devices, reduction for torque-demanding tasks.

Common Pitfalls and How to Avoid Them

Several misunderstandings recur when people talk about ratios like 1:5. Here are the big ones and how to steer clear.

• Ambiguous notation: Don’t say “1:5” alone—state “1:5 speed increase (overdrive)” or “5:1 reduction.”
• Ignoring direction: External gears invert rotation; internal gear stages do not. Belts/chains preserve direction.
• Forgetting efficiency: Expect less torque out than the ideal prediction; multiply by stage efficiencies.
• Overstressing small gears: Extreme tooth-count disparities can push the small gear past allowable contact and bending stress.
• Backlash and precision: High ratios can magnify backlash and compliance; choose tooth forms and preloads appropriately.

A little upfront clarity and sizing discipline prevents most ratio-related surprises.

Quick Reference

Keep these relationships in mind when interpreting or designing around “1 to 5.”

• Speed ratio (ω_out/ω_in) = teeth_in/teeth_out (for external gears); torque ratio (T_out/T_in) = teeth_out/teeth_in.
• 1:5 speed increase (overdrive): speed ×5, torque ×0.2 (ideal). Best to label as “1:5 overdrive.”
• 5:1 reduction: speed ×0.2, torque ×5 (ideal). Best to label as “5:1 reduction.”
• Overall ratio for multi-stage trains = product of stage ratios (considering direction changes per external mesh).

When documenting, pair the number with the intent—overdrive or reduction—to prevent misinterpretation across teams and vendors.

Summary

A 1 to 5 gear ratio typically means one input turn produces five output turns—five times the speed and one-fifth the torque—if you’re using the speed convention (overdrive). Many engineers instead describe the opposite case as a “5:1 reduction,” where output speed drops to one-fifth and torque multiplies by five. Because notation can be ambiguous, always specify whether you mean a speed increase (overdrive) or a reduction, and confirm with tooth counts or RPM values when communicating designs.

What is the 1 to 5 gear ratio?

A 1:5 gear ratio, or “gear reduction,” means the output gear makes five revolutions for every one revolution of the input gear. This is a speed-increasing ratio, creating more mechanical advantage and turning the output gear faster than the input. You can achieve a 1:5 ratio with gears having a 1:5 ratio of teeth, such as an 8-tooth input gear driving a 40-tooth output gear.
 
How it Works

• Input Gear: The driving gear, connected to the power source. 
• Output Gear: The driven gear, which rotates at a different speed and torque than the input gear. 
• Ratio Calculation: To find the gear ratio, divide the number of teeth on the output gear by the number of teeth on the input gear. 

Example

• If an 8-tooth gear (input) drives a 40-tooth gear (output), the ratio is 40 ÷ 8 = 5:1. 
• This means the input gear needs to make 5 revolutions to turn the output gear once, which translates to the output gear spinning 5 times faster. 

Applications

• Speed Increase: Opens in new tabGear ratios like 1:5 are often used to increase the rotational speed of a system, providing more revolutions at the output than at the input. 
• Multi-Stage Gearing: Opens in new tabYou can achieve a 1:5 ratio using multiple gear stages, for example, a 3:5 ratio followed by a 1:3 ratio to get an overall 1:5. 
• Toy Cars & Robotics: Opens in new tabThese ratios are common in educational kits like LEGO Technic to achieve different speeds and torque in robotic projects. 

What is a 5.0:1 gear ratio good for?

Low Gear Ratio (5.0:1 to 5.9:1)
Best for reeling in heavy lures from deep water. Helps you fight big fish without getting as tired. Ideal for deep-diving crankbaits and heavy jigs.

What gear ratio increases speed?

A lower (taller) gear ratio provides a higher top speed, and a higher (shorter) gear ratio provides faster acceleration. . Besides the gears in the transmission, there is also a gear in the rear differential. This is known as the final drive, differential gear, Crown Wheel Pinion (CWP) or ring and pinion.

What is a gear ratio for dummies?

You just count the number of teeth on the two gears and divide the two numbers. So if one gear has 60 teeth and another has 20, the gear ratio when these two gears are connected together is 3:1. They make it so that slight imperfections in the actual diameter and circumference of two gears don’t matter.