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	3.03	4.68	6.92	9.83	12.14	15.86
600	3.64	5.62	8.31	11.8	14.56	19.03
700	4.25	6.55	9.69	13.76	16.99	22.2
800	4.85	7.49	11.08	15.73	19.42	25.37
900	5.46	8.43	12.46	17.7	21.85	28.54
1000	6.07	9.36	13.85	19.66	24.27	31.71
1100	6.68	10.3	15.23	21.63	26.7	34.88
1200	7.28	11.24	16.62	23.59	29.13	38.06
1300	7.89	12.17	18	25.56	31.56	41.23
1400	8.5	13.11	19.39	27.53	33.98	44.4
1500	9.1	14.04	20.77	29.49	36.41	47.57
1600	9.71	14.98	22.15	31.46	38.84	50.74
1700	10.32	15.92	23.54	33.43	41.27	53.91
1800	10.92	16.85	24.92	35.39	43.69	57.08
1900	11.53	17.79	26.31	37.36	46.12	60.26
2000	12.14	18.73	27.69	39.32	48.55	63.43
2100	12.74	19.66	29.08	41.29	50.98	66.6
2200	13.35	20.6	30.46	43.26	53.4	69.77
2300	13.96	21.53	31.85	45.22	55.83	72.94
2400	14.56	22.47	33.23	47.19	58.26	76.11
2500	15.17	23.41	34.62	49.16	60.69	79.28
2600	15.78	24.34	36	51.12	63.11	82.45
2700	16.39	25.28	37.39	53.09	65.54	85.63
2800	16.99	26.22	38.77	55.05	67.97	88.8
2900	17.6	27.15	40.16	57.02	70.4	91.97
3000	18.21	28.09	41.54	58.99	72.82	95.14
3100	18.81	29.03	42.92	60.95	75.25	98.31
3200	19.42	29.96	44.31	62.92	77.68	101.48
3300	20.03	30.9	45.69	64.89	80.11	104.65
3400	20.63	31.83	47.08	66.85	82.53	107.83
3500	21.24	32.77	48.46	68.82	84.96	111
3600	21.85	33.71	49.85	70.78	87.39	114.17
3700	22.45	34.64	51.23	72.75	89.82	117.34
3800	23.06	35.58	52.62	74.72	92.24	120.51
3900	23.67	36.52	54	76.68	94.67	123.68
4000	24.27	37.45	55.39	78.65	97.1	126.85
4100	24.88	38.39	56.77	80.62	99.52	130.02
4200	25.49	39.32	58.16	82.58	101.95	133.2
4300	26.09	40.26	59.54	84.55	104.38	136.37
4400	26.7	41.2	60.93	86.51	106.81	139.54
4500	27.31	42.13	62.31	88.48	109.23	142.71
4600	27.92	43.07	63.69	90.45	111.66	145.88
4700	28.52	44.01	65.08	92.41	114.09	149.05
4800	29.13	44.94	66.46	94.38	116.52	152.22
4900	29.74	45.88	67.85	96.34	118.94	155.4
5000	30.34	46.81	69.23	98.31	121.37	158.57
5100	30.95	47.75	70.62	100.28	123.8	161.74
5200	31.56	48.69	72	102.24	126.23	164.91
5300	32.16	49.62	73.39	104.21	128.65	168.08
5400	32.77	50.56	74.77	106.18	131.08	171.25
5500	33.38	51.5	76.16	108.14	133.51	174.42
5600	33.98	52.43	77.54	110.11	135.94	177.59
5700	34.59	53.37	78.93	112.07	138.36	180.77
5800	35.2	54.31	80.31	114.04	140.79	183.94
5900	35.8	55.24	81.7	116.01	143.22	187.11
6000	36.41	56.18	83.08	117.97	145.65	190.28
6100	37.02	57.11	84.46	119.94	148.07	193.45
6200	37.63	58.05	85.85	121.91	150.5	196.62
6300	38.23	58.99	87.23	123.87	152.93	199.79
6400	38.84	59.92	88.62	125.84	155.36	202.96
6500	39.45	60.86	90	127.8	157.78	206.14
6600	40.05	61.8	91.39	129.77	160.21	209.31
6700	40.66	62.73	92.77	131.74	162.64	212.48
6800	41.27	63.67	94.16	133.7	165.07	215.65
6900	41.87	64.6	95.54	135.67	167.49	218.82
7000	42.48	65.54	96.93	137.64	169.92	221.99
7100	43.09	66.48	98.31	139.6	172.35	225.16
7200	43.69	67.41	99.7	141.57	174.78	228.34
7300	44.3	68.35	101.08	143.53	177.2	231.51
7400	44.91	69.29	102.47	145.5	179.63	234.68
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