Gear Ratios Calculator, MPH, Top Speed

This calculator outputs the how fast a car can go in each gear as calculated by the gear ratios, engine redline and tire size.
The ultimate top speed may be limted by the power, drag and aerodynamics of each individual car.

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Tire Size (345/30/20)	/ -
Tire Diameter (inches)

Final Drive Ratio
Redline (RPM)
1st Gear
2nd Gear
3rd Gear
4th Gear
5th Gear
6th Gear
7th Gear
8th Gear

RPM	1st Gear	2nd Gear	3rd Gear	4th Gear	5th Gear	6th Gear	7th Gear	8th Gear
500	2.3	3.9	5.37	7.46	8.8	11.14	0	0
600	2.77	4.67	6.44	8.95	10.56	13.37	0	0
700	3.23	5.45	7.51	10.44	12.32	15.6	0	0
800	3.69	6.23	8.59	11.94	14.08	17.83	0	0
900	4.15	7.01	9.66	13.43	15.85	20.06	0	0
1000	4.61	7.79	10.74	14.92	17.61	22.29	0	0
1100	5.07	8.57	11.81	16.41	19.37	24.51	0	0
1200	5.53	9.35	12.88	17.9	21.13	26.74	0	0
1300	5.99	10.13	13.96	19.4	22.89	28.97	0	0
1400	6.45	10.91	15.03	20.89	24.65	31.2	0	0
1500	6.91	11.69	16.1	22.38	26.41	33.43	0	0
1600	7.37	12.46	17.18	23.87	28.17	35.66	0	0
1700	7.84	13.24	18.25	25.36	29.93	37.89	0	0
1800	8.3	14.02	19.32	26.86	31.69	40.11	0	0
1900	8.76	14.8	20.4	28.35	33.45	42.34	0	0
2000	9.22	15.58	21.47	29.84	35.21	44.57	0	0
2100	9.68	16.36	22.54	31.33	36.97	46.8	0	0
2200	10.14	17.14	23.62	32.82	38.73	49.03	0	0
2300	10.6	17.92	24.69	34.32	40.49	51.26	0	0
2400	11.06	18.7	25.76	35.81	42.25	53.49	0	0
2500	11.52	19.48	26.84	37.3	44.01	55.72	0	0
2600	11.98	20.25	27.91	38.79	45.78	57.94	0	0
2700	12.44	21.03	28.99	40.28	47.54	60.17	0	0
2800	12.9	21.81	30.06	41.78	49.3	62.4	0	0
2900	13.37	22.59	31.13	43.27	51.06	64.63	0	0
3000	13.83	23.37	32.21	44.76	52.82	66.86	0	0
3100	14.29	24.15	33.28	46.25	54.58	69.09	0	0
3200	14.75	24.93	34.35	47.75	56.34	71.32	0	0
3300	15.21	25.71	35.43	49.24	58.1	73.54	0	0
3400	15.67	26.49	36.5	50.73	59.86	75.77	0	0
3500	16.13	27.27	37.57	52.22	61.62	78	0	0
3600	16.59	28.04	38.65	53.71	63.38	80.23	0	0
3700	17.05	28.82	39.72	55.21	65.14	82.46	0	0
3800	17.51	29.6	40.79	56.7	66.9	84.69	0	0
3900	17.97	30.38	41.87	58.19	68.66	86.92	0	0
4000	18.44	31.16	42.94	59.68	70.42	89.14	0	0
4100	18.9	31.94	44.01	61.17	72.18	91.37	0	0
4200	19.36	32.72	45.09	62.67	73.95	93.6	0	0
4300	19.82	33.5	46.16	64.16	75.71	95.83	0	0
4400	20.28	34.28	47.24	65.65	77.47	98.06	0	0
4500	20.74	35.06	48.31	67.14	79.23	100.29	0	0
4600	21.2	35.84	49.38	68.63	80.99	102.52	0	0
4700	21.66	36.61	50.46	70.13	82.75	104.74	0	0
4800	22.12	37.39	51.53	71.62	84.51	106.97	0	0
4900	22.58	38.17	52.6	73.11	86.27	109.2	0	0
5000	23.04	38.95	53.68	74.6	88.03	111.43	0	0
5100	23.51	39.73	54.75	76.09	89.79	113.66	0	0
5200	23.97	40.51	55.82	77.59	91.55	115.89	0	0
5300	24.43	41.29	56.9	79.08	93.31	118.12	0	0
5400	24.89	42.07	57.97	80.57	95.07	120.34	0	0
5500	25.35	42.85	59.04	82.06	96.83	122.57	0	0
5600	25.81	43.63	60.12	83.55	98.59	124.8	0	0
5700	26.27	44.4	61.19	85.05	100.35	127.03	0	0
5800	26.73	45.18	62.27	86.54	102.11	129.26	0	0
5900	27.19	45.96	63.34	88.03	103.88	131.49	0	0
6000	27.65	46.74	64.41	89.52	105.64	133.72	0	0
6100	28.11	47.52	65.49	91.01	107.4	135.95	0	0
6200	28.58	48.3	66.56	92.51	109.16	138.17	0	0
6300	29.04	49.08	67.63	94	110.92	140.4	0	0
6400	29.5	49.86	68.71	95.49	112.68	142.63	0	0
6500	29.96	50.64	69.78	96.98	114.44	144.86	0	0
6600	30.42	51.42	70.85	98.47	116.2	147.09	0	0
6700	30.88	52.19	71.93	99.97	117.96	149.32	0	0
6800	31.34	52.97	73	101.46	119.72	151.55	0	0
6900	31.8	53.75	74.07	102.95	121.48	153.77	0	0
7000	32.26	54.53	75.15	104.44	123.24	156	0	0
7100	32.72	55.31	76.22	105.93	125	158.23	0	0
7200	33.18	56.09	77.29	107.43	126.76	160.46	0	0
RPM	1st Gear	2nd Gear	3rd Gear	4th Gear	5th Gear	6th Gear	7th Gear	8th Gear

Some additional information on how these are calculated:

When D is the diameter of the tire, the car moves forward a distance πD with each revolution of the tire. If there are F revolutions per unit of time, it moves forward at a speed of πD´F per unit of time. If D is in inches and F is in revolutions per minute (rpm), the above result will be in inches per minute. There are 63,360 inches in a mile and 60 minutes in an hour, so one inch per minute equals 60/63360 miles per hour or 1/1056 mph. So we have the following formula:

V(mph) = D(in) ´ F(rpm) ´ (π/1056)

In the automotive industry, the coefficient 1056/π is usually taken to be equal to 336 (exactly it is 336.1352398...) and the formula corresponding to the above is:

(mph)(gear ratio)(336) = (tire diameter in inches)(rpm)

With the above numerical approximation, both formulas are identical if we consider that (rpm)/(gear ratio) is the rate of rotation of the tires. So the "gear ratio" as the number of rotations of the driveshaft for each turn of the tire. This ratio is normally more than 1, except in overdrive gear. So, calling R the "gear ratio", your final answer is:

V(mph) = D(in) ´ F(rpm) ´ (π/1056) / R

or, approximately: V = (D ´ F) / (336 ´ R)

where V is the velocity (in mph), D the tire diameter (in inches), F the engine rpm, and R the gear ratio.

Gear Ratio Calculator >>

Gear Ratios Calculator, MPH, Top Speed