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	2.51	3.76	5.63	7.08	9.16	11.82	14.07	17.64
600	3.01	4.52	6.75	8.49	10.99	14.18	16.88	21.17
700	3.51	5.27	7.88	9.91	12.83	16.54	19.7	24.69
800	4.01	6.02	9	11.32	14.66	18.91	22.51	28.22
900	4.52	6.77	10.13	12.74	16.49	21.27	25.32	31.75
1000	5.02	7.53	11.25	14.15	18.32	23.64	28.14	35.28
1100	5.52	8.28	12.38	15.57	20.15	26	30.95	38.8
1200	6.02	9.03	13.51	16.98	21.99	28.36	33.76	42.33
1300	6.52	9.79	14.63	18.4	23.82	30.73	36.58	45.86
1400	7.03	10.54	15.76	19.81	25.65	33.09	39.39	49.39
1500	7.53	11.29	16.88	21.23	27.48	35.45	42.21	52.92
1600	8.03	12.04	18.01	22.64	29.32	37.82	45.02	56.44
1700	8.53	12.8	19.13	24.06	31.15	40.18	47.83	59.97
1800	9.03	13.55	20.26	25.48	32.98	42.54	50.65	63.5
1900	9.53	14.3	21.38	26.89	34.81	44.91	53.46	67.03
2000	10.04	15.05	22.51	28.31	36.64	47.27	56.27	70.55
2100	10.54	15.81	23.64	29.72	38.48	49.63	59.09	74.08
2200	11.04	16.56	24.76	31.14	40.31	52	61.9	77.61
2300	11.54	17.31	25.89	32.55	42.14	54.36	64.72	81.14
2400	12.04	18.07	27.01	33.97	43.97	56.73	67.53	84.66
2500	12.55	18.82	28.14	35.38	45.81	59.09	70.34	88.19
2600	13.05	19.57	29.26	36.8	47.64	61.45	73.16	91.72
2700	13.55	20.32	30.39	38.21	49.47	63.82	75.97	95.25
2800	14.05	21.08	31.51	39.63	51.3	66.18	78.78	98.78
2900	14.55	21.83	32.64	41.04	53.13	68.54	81.6	102.3
3000	15.05	22.58	33.76	42.46	54.97	70.91	84.41	105.83
3100	15.56	23.33	34.89	43.87	56.8	73.27	87.23	109.36
3200	16.06	24.09	36.02	45.29	58.63	75.63	90.04	112.89
3300	16.56	24.84	37.14	46.7	60.46	78	92.85	116.41
3400	17.06	25.59	38.27	48.12	62.3	80.36	95.67	119.94
3500	17.56	26.35	39.39	49.54	64.13	82.72	98.48	123.47
3600	18.07	27.1	40.52	50.95	65.96	85.09	101.29	127
3700	18.57	27.85	41.64	52.37	67.79	87.45	104.11	130.52
3800	19.07	28.6	42.77	53.78	69.62	89.81	106.92	134.05
3900	19.57	29.36	43.89	55.2	71.46	92.18	109.74	137.58
4000	20.07	30.11	45.02	56.61	73.29	94.54	112.55	141.11
4100	20.57	30.86	46.15	58.03	75.12	96.91	115.36	144.63
4200	21.08	31.61	47.27	59.44	76.95	99.27	118.18	148.16
4300	21.58	32.37	48.4	60.86	78.78	101.63	120.99	151.69
4400	22.08	33.12	49.52	62.27	80.62	104	123.8	155.22
4500	22.58	33.87	50.65	63.69	82.45	106.36	126.62	158.75
4600	23.08	34.63	51.77	65.1	84.28	108.72	129.43	162.27
4700	23.59	35.38	52.9	66.52	86.11	111.09	132.25	165.8
4800	24.09	36.13	54.02	67.93	87.95	113.45	135.06	169.33
4900	24.59	36.88	55.15	69.35	89.78	115.81	137.87	172.86
5000	25.09	37.64	56.27	70.76	91.61	118.18	140.69	176.38
5100	25.59	38.39	57.4	72.18	93.44	120.54	143.5	179.91
5200	26.09	39.14	58.53	73.6	95.27	122.9	146.31	183.44
5300	26.6	39.89	59.65	75.01	97.11	125.27	149.13	186.97
5400	27.1	40.65	60.78	76.43	98.94	127.63	151.94	190.49
5500	27.6	41.4	61.9	77.84	100.77	130	154.76	194.02
5600	28.1	42.15	63.03	79.26	102.6	132.36	157.57	197.55
5700	28.6	42.91	64.15	80.67	104.44	134.72	160.38	201.08
5800	29.11	43.66	65.28	82.09	106.27	137.09	163.2	204.61
5900	29.61	44.41	66.4	83.5	108.1	139.45	166.01	208.13
6000	30.11	45.16	67.53	84.92	109.93	141.81	168.82	211.66
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