Gear Ratio Calculator

The Gear Ratio Calculator determines the gear ratio of the circumference and the vehicle's speed in any gear and any engine RPM for the best performance. This enables you to know the relationship between the speed and torque in a mechanical system. We've integrated this calculator with the gear ratio formula to find out the ratio of the gear.

What is Gear?

A gear is a rotating mechanical component with teeth designed to transmit power and motion by meshing with other gears or toothed parts. By using gears, you can change the rotational speed, direction, and torque that is applied to it.

What is Gear Ratio?

"The ratio between the rotational speed of the final and the initial gear"

The Gear ratio communicates the degree of speed alteration and the torque variation experienced by the output gear in the system. It enables you to know how fast your vehicle can go in each gear at different engine RPMs for top performance.

A high gear ratio will result in a slower speed but higher torque.
A low gear ratio will result in a higher speed but lower torque.

Gears

How To Calculate Gear Ratio?

Below are the gear ratio equations to calculate the gear ratio so, follow these for manual calculation.

Gear Ratio Equations:

Let’s have a look at the relative equations that you could use to calculate the gear ratio accurately.

Formula # 1: The expression relates the circumference of the input gear to that of the output gear.

Gear Ratio = (π * Diameter of Input Gear)/(π * Diameter of Output Gear)

Formula # 2: When only diameters is known:

Gear Ratio = (Diameter of Input Gear)/(Diameter of Output Gear)

Formula # 3: When Radius is known:

Gear Ratio = (Radius of Input Gear)/(Radius of Output Gear)

Formula # 4: When the circumference of Input and the circumference of Output number of Gear Teeth are taken into account:

Gear Ratio = (Input Gear Teeth Number * (Gear Thickness + Teeth Spacing)) / (Output Gear Teeth Number * (Gear Thickness + Teeth Spacing))

Formula # 5: For smooth running of the gear, the thickness of each tooth along with spacing must be the same. That is why we will vanish these parameters from the above equation:

Gear Ratio = Input Gear Teeth Number / Output Gear Teeth Number

Gear Ratio Example:

Suppose two-gear system in which the pinnion gear has 52 teeths and other ring gear consists of 14 teeths. So, find that what is the ratio between pinnion gear and ring gear. Answer:

Gear Ratio = Input Number of Gear Teeth / Output Number of Gear Teeth = 52 / 14 = 3.71:1

So, it is determined that 3.71:1 ratio is concluded for the number of teeth in which each gear needs to produce a desired output speed or torque.

Gear Ratio Chart:

DIAMETER	GEAR RATIO
25"	2385	2568	2682	2804	2892	2988	3101	3259	3416	3590	3730	3984	4263	4482	4621	4700	4988	5390
26"	2293	2470	2579	2696	2780	2873	2982	3133	3284	3452	3587	3830	4099	4309	4444	4519	4796	5183
27"	2208	2378	2483	2597	2677	2766	2872	3017	3163	3325	3454	3689	3947	4150	4279	4352	4619	4991
28"	2129	2293	2395	2504	2582	2668	2769	2909	3050	3206	3331	3557	3806	4001	4126	4196	4454	4813
29"	2056	2214	2312	2417	2493	2576	2674	2809	2945	3095	3216	3434	3675	3863	3984	4052	4300	4647
30"	1987	2140	2235	2337	2410	2490	2584	2715	2846	2992	3109	3320	3553	3735	3851	3917	4157	4492
31"	1923	2071	2163	2261	2332	2409	2501	2628	2755	2896	3008	3213	3438	3614	3727	3790	4023	4347
32"	1863	2007	2095	2191	2259	2334	2423	2546	2669	2805	2914	3112	3331	3501	3610	3672	3897	4211
33"	1807	1946	2032	2124	2191	2263	2349	2469	2588	2720	2826	3018	3230	3395	3501	3561	3779	4083
34"	1754	1889	1972	2062	2126	2197	2280	2396	2512	2640	2743	2929	3135	3295	3398	3456	3668	3963
35"	1704	1835	1916	2003	2065	2134	2215	2328	2440	2565	2664	2845	3045	3201	3301	3357	3563	3850
36"	1656	1784	1862	1947	2008	2075	2154	2263	2372	2493	2590	2766	2961	3112	3209	3264	3464	3743
37"	1611	1735	1812	1895	1954	2019	2095	2202	2308	2426	2520	2692	2881	3028	3123	3176	3370	3642
38"	1569	1690	1764	1845	1902	1966	2040	2144	2247	2362	2454	2621	2805	2948	3040	3092	3282	3546
39"	1529	1646	1719	1798	1854	1915	1988	2089	2190	2302	2391	2554	2733	2873	2962	3013	3198	3455
40"	1491	1605	1676	1753	1807	1867	1938	2037	2135	2244	2331	2490	2664	2801	2888	2937	3118	3369
41"	1454	1566	1635	1710	1763	1822	1891	1987	2083	2189	2275	2492	2599	2733	2818	2866	3042	3287
42"	1420	1529	1596	1669	1721	1778	1846	1940	2033	2137	2220	2371	2538	2668	2751	2798	2969	3208
43"	1387	1493	1559	1630	1681	1737	1803	1894	1986	2087	2169	2316	2479	2606	2687	2733	2900	3134
44"	1355	1459	1524	1593	1643	1698	1762	1851	1941	2040	2119	2263	2422	2545	2626	2670	2834	3063

Steps To Utilize The Calculator:

The gear ratio calculator finds the rate of mechanical advantage or disadvantage a gear train produces in the gear system.

Required Values:

For Simple Mode:

Enter input and output gear teeth number
Likewise, enter the rotational speed and torque
At the end, hit the calculate button

For Advanced Mode:

Enter the Engine RPM (Revolutions per minute), Axle Ratio, and Tire height in respective fields
Likewise, enter the Tire Width, Wheel Diameter, and Aspect Ratios in their designated fields
After you are done, hit the calculate button

Final Results:

The gear ratio
Mechanical advantage
Rotational speed and torque of gear axle
Width and height of the tire
Miles Per Hour (MPH) for a gear speed

Additional Querries:

What is a good gear ratio?

Normally, the gear ratio lower than 4.56 is considered better for smooth running of the gear, and thus the whole machine. If you want your ride to run without no knocking sound, then you should keep utilising this online gear ratio rpm calculator to keep an idea of your ride’s good performance.

Which gear ratio provides best fuel economy?

To drive heavier truck like vehicles, you must go for choosing a low gear ratio as 3.0, 3.23, or 3.31. But when it comes to the city cars, the axle ratio is not so affected by the MPG.