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	2.64	4.71	7.25	9.65	12.72	15.96	0	0
600	3.17	5.66	8.7	11.58	15.27	19.16	0	0
700	3.7	6.6	10.15	13.51	17.81	22.35	0	0
800	4.23	7.54	11.6	15.44	20.36	25.54	0	0
900	4.76	8.49	13.05	17.37	22.9	28.74	0	0
1000	5.29	9.43	14.51	19.3	25.45	31.93	0	0
1100	5.82	10.37	15.96	21.23	27.99	35.12	0	0
1200	6.35	11.31	17.41	23.16	30.54	38.31	0	0
1300	6.88	12.26	18.86	25.09	33.08	41.51	0	0
1400	7.41	13.2	20.31	27.02	35.63	44.7	0	0
1500	7.93	14.14	21.76	28.95	38.17	47.89	0	0
1600	8.46	15.09	23.21	30.88	40.71	51.09	0	0
1700	8.99	16.03	24.66	32.81	43.26	54.28	0	0
1800	9.52	16.97	26.11	34.74	45.8	57.47	0	0
1900	10.05	17.91	27.56	36.67	48.35	60.66	0	0
2000	10.58	18.86	29.01	38.6	50.89	63.86	0	0
2100	11.11	19.8	30.46	40.53	53.44	67.05	0	0
2200	11.64	20.74	31.91	42.46	55.98	70.24	0	0
2300	12.17	21.69	33.36	44.39	58.53	73.43	0	0
2400	12.69	22.63	34.81	46.33	61.07	76.63	0	0
2500	13.22	23.57	36.26	48.26	63.62	79.82	0	0
2600	13.75	24.51	37.71	50.19	66.16	83.01	0	0
2700	14.28	25.46	39.16	52.12	68.71	86.21	0	0
2800	14.81	26.4	40.61	54.05	71.25	89.4	0	0
2900	15.34	27.34	42.06	55.98	73.8	92.59	0	0
3000	15.87	28.29	43.52	57.91	76.34	95.78	0	0
3100	16.4	29.23	44.97	59.84	78.88	98.98	0	0
3200	16.93	30.17	46.42	61.77	81.43	102.17	0	0
3300	17.46	31.11	47.87	63.7	83.97	105.36	0	0
3400	17.98	32.06	49.32	65.63	86.52	108.56	0	0
3500	18.51	33	50.77	67.56	89.06	111.75	0	0
3600	19.04	33.94	52.22	69.49	91.61	114.94	0	0
3700	19.57	34.88	53.67	71.42	94.15	118.13	0	0
3800	20.1	35.83	55.12	73.35	96.7	121.33	0	0
3900	20.63	36.77	56.57	75.28	99.24	124.52	0	0
4000	21.16	37.71	58.02	77.21	101.79	127.71	0	0
4100	21.69	38.66	59.47	79.14	104.33	130.91	0	0
4200	22.22	39.6	60.92	81.07	106.88	134.1	0	0
4300	22.74	40.54	62.37	83	109.42	137.29	0	0
4400	23.27	41.48	63.82	84.93	111.97	140.48	0	0
4500	23.8	42.43	65.27	86.86	114.51	143.68	0	0
4600	24.33	43.37	66.72	88.79	117.06	146.87	0	0
4700	24.86	44.31	68.17	90.72	119.6	150.06	0	0
4800	25.39	45.26	69.62	92.65	122.14	153.26	0	0
4900	25.92	46.2	71.08	94.58	124.69	156.45	0	0
5000	26.45	47.14	72.53	96.51	127.23	159.64	0	0
5100	26.98	48.08	73.98	98.44	129.78	162.83	0	0
5200	27.51	49.03	75.43	100.37	132.32	166.03	0	0
5300	28.03	49.97	76.88	102.3	134.87	169.22	0	0
5400	28.56	50.91	78.33	104.23	137.41	172.41	0	0
5500	29.09	51.86	79.78	106.16	139.96	175.6	0	0
5600	29.62	52.8	81.23	108.09	142.5	178.8	0	0
5700	30.15	53.74	82.68	110.02	145.05	181.99	0	0
5800	30.68	54.68	84.13	111.95	147.59	185.18	0	0
5900	31.21	55.63	85.58	113.88	150.14	188.38	0	0
6000	31.74	56.57	87.03	115.81	152.68	191.57	0	0
6100	32.27	57.51	88.48	117.74	155.23	194.76	0	0
6200	32.79	58.46	89.93	119.67	157.77	197.95	0	0
6300	33.32	59.4	91.38	121.6	160.31	201.15	0	0
6400	33.85	60.34	92.83	123.53	162.86	204.34	0	0
6500	34.38	61.28	94.28	125.46	165.4	207.53	0	0
6600	34.91	62.23	95.73	127.39	167.95	210.73	0	0
6700	35.44	63.17	97.18	129.32	170.49	213.92	0	0
6800	35.97	64.11	98.64	131.25	173.04	217.11	0	0
6900	36.5	65.06	100.09	133.18	175.58	220.3	0	0
7000	37.03	66	101.54	135.11	178.13	223.5	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