A Chart of Wheel Sizes with an explanation of BikeCalc's math.
Feedback? Email me.
Jump down to the Wheel Size Chart.

What size is my wheel? (The logical version)

  • Given rim diameter (the ISO diameter)
  • and tire diameter (the size of your tire converted to millimeters)
  • Wheel diameter = (rim diameter) + (tire diameter * 2).
  • Wheel circumference = Wheel diameter * PI.
Since the tire wraps around your rim, the wheel diameter includes the tire on both sides (thus the multiplication by 2).

BikeCalc takes this view.  I won't argue that it's correct, just that it's simple and as likely to be right as any other strategy.

The table below lists all the wheel sizes in BikeCalc.  If your rim/tire combination isn't listed
  • measure your wheel and use the BikeCalc rim/tire combination that will result
    in the nearest circumference or
  • email me your rim/tire sizes and I'll add them to BikeCalc.

Why are all wheel size calculations wrong? (The rebuttal)

The venerable Sheldon Brown has a Gear Calculator that uses a different method to determine wheel size.  His calculator uses an pre-defined diameter for every rim/tire combination and his diameters are almost always different than what the math would predict.

Why is this? I have no idea. Perhaps he actually measured all the combinations and knew the real sizes, at least for the specific tires he was measuring on that day.

Regardless, ponder these questions:
  • Who manufactured your tire?  Is every 23mm tire (for example) exactly the same?
  • How worn is your tire?
  • How much air is in your tire?

All of these things conspire to make any calculation a guess.  Since we're talking about very small variations, any reasonable method of determining wheel size is good enough.    Just make sure you do your comparisons using the same calculator, or if you use several calculators, that you know exactly how each is determining wheel circumference.

BikeCalc Wheel Sizes

This combination of ... results in these diameters (mm) ... Circumference
Rim Tire Rim (iso) Tire Wheel of Wheel
27inch 20 mm 630 20.00 670.00 2104.87
27inch 23 mm 630 23.00 676.00 2123.72
27inch 25 mm 630 25.00 680.00 2136.28
27inch 28 mm 630 28.00 686.00 2155.13
27inch 32 mm 630 32.00 694.00 2180.27
27inch 35 mm 630 35.00 700.00 2199.11
27inch 38 mm 630 38.00 706.00 2217.96
27inch 44 mm 630 44.00 718.00 2255.66
27inch 50 mm 630 50.00 730.00 2293.36
27inch 56 mm 630 56.00 742.00 2331.06
27inch 1.00 inch 630 25.40 680.80 2138.80
27inch 1.25 inch 630 31.75 693.50 2178.69
27inch 1.5 inch 630 38.10 706.20 2218.59
27inch 1.75 inch 630 44.45 718.90 2258.49
27inch 1.90 inch 630 48.26 726.52 2282.43
27inch 1.95 inch 630 49.50 729.00 2290.22
27inch 2.00 inch 630 50.80 731.60 2298.39
27inch 2.10 inch 630 53.34 736.68 2314.35
27inch 2.125 inch 630 54.00 738.00 2318.50
27inch 2.20 inch 630 55.88 741.76 2330.31
27inch 2.25 inch 630 57.15 744.30 2338.29
27inch 2.30 inch 630 58.42 746.84 2346.27
27inch 2.35 inch 630 59.69 749.38 2354.25
27inch 2.40 inch 630 60.69 751.38 2360.53
700c/29er 20 mm 622 20.00 662.00 2079.73
700c/29er 23 mm 622 23.00 668.00 2098.58
700c/29er 25 mm 622 25.00 672.00 2111.15
700c/29er 28 mm 622 28.00 678.00 2130.00
700c/29er 32 mm 622 32.00 686.00 2155.13
700c/29er 35 mm 622 35.00 692.00 2173.98
700c/29er 38 mm 622 38.00 698.00 2192.83
700c/29er 44 mm 622 44.00 710.00 2230.53
700c/29er 50 mm 622 50.00 722.00 2268.23
700c/29er 56 mm 622 56.00 734.00 2305.93
700c/29er 1.00 inch 622 25.40 672.80 2113.66
700c/29er 1.25 inch 622 31.75 685.50 2153.56
700c/29er 1.5 inch 622 38.10 698.20 2193.46
700c/29er 1.75 inch 622 44.45 710.90 2233.36
700c/29er 1.90 inch 622 48.26 718.52 2257.30
700c/29er 1.95 inch 622 49.50 721.00 2265.09
700c/29er 2.00 inch 622 50.80 723.60 2273.26
700c/29er 2.10 inch 622 53.34 728.68 2289.22
700c/29er 2.125 inch 622 54.00 730.00 2293.36
700c/29er 2.20 inch 622 55.88 733.76 2305.18
700c/29er 2.25 inch 622 57.15 736.30 2313.15
700c/29er 2.30 inch 622 58.42 738.84 2321.13
700c/29er 2.35 inch 622 59.69 741.38 2329.11
700c/29er 2.40 inch 622 60.69 743.38 2335.40
650b/27.5 20 mm 584 20.00 624.00 1960.35
650b/27.5 23 mm 584 23.00 630.00 1979.20
650b/27.5 25 mm 584 25.00 634.00 1991.77
650b/27.5 28 mm 584 28.00 640.00 2010.62
650b/27.5 32 mm 584 32.00 648.00 2035.75
650b/27.5 35 mm 584 35.00 654.00 2054.60
650b/27.5 38 mm 584 38.00 660.00 2073.45
650b/27.5 44 mm 584 44.00 672.00 2111.15
650b/27.5 50 mm 584 50.00 684.00 2148.85
650b/27.5 56 mm 584 56.00 696.00 2186.55
650b/27.5 1.00 inch 584 25.40 634.80 1994.28
650b/27.5 1.25 inch 584 31.75 647.50 2034.18
650b/27.5 1.5 inch 584 38.10 660.20 2074.08
650b/27.5 1.75 inch 584 44.45 672.90 2113.98
650b/27.5 1.90 inch 584 48.26 680.52 2137.92
650b/27.5 1.95 inch 584 49.50 683.00 2145.71
650b/27.5 2.00 inch 584 50.80 685.60 2153.88
650b/27.5 2.10 inch 584 53.34 690.68 2169.84
650b/27.5 2.125 inch 584 54.00 692.00 2173.98
650b/27.5 2.20 inch 584 55.88 695.76 2185.79
650b/27.5 2.25 inch 584 57.15 698.30 2193.77
650b/27.5 2.30 inch 584 58.42 700.84 2201.75
650b/27.5 2.35 inch 584 59.69 703.38 2209.73
650b/27.5 2.40 inch 584 60.69 705.38 2216.02
650c 20 mm 571 20.00 611.00 1919.51
650c 23 mm 571 23.00 617.00 1938.36
650c 25 mm 571 25.00 621.00 1950.93
650c 28 mm 571 28.00 627.00 1969.78
650c 32 mm 571 32.00 635.00 1994.91
650c 35 mm 571 35.00 641.00 2013.76
650c 38 mm 571 38.00 647.00 2032.61
650c 44 mm 571 44.00 659.00 2070.31
650c 50 mm 571 50.00 671.00 2108.01
650c 56 mm 571 56.00 683.00 2145.71
650c 1.00 inch 571 25.40 621.80 1953.44
650c 1.25 inch 571 31.75 634.50 1993.34
650c 1.5 inch 571 38.10 647.20 2033.24
650c 1.75 inch 571 44.45 659.90 2073.14
650c 1.90 inch 571 48.26 667.52 2097.08
650c 1.95 inch 571 49.50 670.00 2104.87
650c 2.00 inch 571 50.80 672.60 2113.04
650c 2.10 inch 571 53.34 677.68 2128.99
650c 2.125 inch 571 54.00 679.00 2133.14
650c 2.20 inch 571 55.88 682.76 2144.95
650c 2.25 inch 571 57.15 685.30 2152.93
650c 2.30 inch 571 58.42 687.84 2160.91
650c 2.35 inch 571 59.69 690.38 2168.89
650c 2.40 inch 571 60.69 692.38 2175.18
26inch mtb 20 mm 559 20.00 599.00 1881.81
26inch mtb 23 mm 559 23.00 605.00 1900.66
26inch mtb 25 mm 559 25.00 609.00 1913.23
26inch mtb 28 mm 559 28.00 615.00 1932.08
26inch mtb 32 mm 559 32.00 623.00 1957.21
26inch mtb 35 mm 559 35.00 629.00 1976.06
26inch mtb 38 mm 559 38.00 635.00 1994.91
26inch mtb 44 mm 559 44.00 647.00 2032.61
26inch mtb 50 mm 559 50.00 659.00 2070.31
26inch mtb 56 mm 559 56.00 671.00 2108.01
26inch mtb 1.00 inch 559 25.40 609.80 1915.74
26inch mtb 1.25 inch 559 31.75 622.50 1955.64
26inch mtb 1.5 inch 559 38.10 635.20 1995.54
26inch mtb 1.75 inch 559 44.45 647.90 2035.44
26inch mtb 1.90 inch 559 48.26 655.52 2059.38
26inch mtb 1.95 inch 559 49.50 658.00 2067.17
26inch mtb 2.00 inch 559 50.80 660.60 2075.34
26inch mtb 2.10 inch 559 53.34 665.68 2091.30
26inch mtb 2.125 inch 559 54.00 667.00 2095.44
26inch mtb 2.20 inch 559 55.88 670.76 2107.25
26inch mtb 2.25 inch 559 57.15 673.30 2115.23
26inch mtb 2.30 inch 559 58.42 675.84 2123.21
26inch mtb 2.35 inch 559 59.69 678.38 2131.19
26inch mtb 2.40 inch 559 60.69 680.38 2137.48
24inch S5 20 mm 547 20.00 587.00 1844.11
24inch S5 23 mm 547 23.00 593.00 1862.96
24inch S5 25 mm 547 25.00 597.00 1875.53
24inch S5 28 mm 547 28.00 603.00 1894.38
24inch S5 32 mm 547 32.00 611.00 1919.51
24inch S5 35 mm 547 35.00 617.00 1938.36
24inch S5 38 mm 547 38.00 623.00 1957.21
24inch S5 44 mm 547 44.00 635.00 1994.91
24inch S5 50 mm 547 50.00 647.00 2032.61
24inch S5 56 mm 547 56.00 659.00 2070.31
24inch S5 1.00 inch 547 25.40 597.80 1878.04
24inch S5 1.25 inch 547 31.75 610.50 1917.94
24inch S5 1.5 inch 547 38.10 623.20 1957.84
24inch S5 1.75 inch 547 44.45 635.90 1997.74
24inch S5 1.90 inch 547 48.26 643.52 2021.68
24inch S5 1.95 inch 547 49.50 646.00 2029.47
24inch S5 2.00 inch 547 50.80 648.60 2037.64
24inch S5 2.10 inch 547 53.34 653.68 2053.60
24inch S5 2.125 inch 547 54.00 655.00 2057.74
24inch S5 2.20 inch 547 55.88 658.76 2069.56
24inch S5 2.25 inch 547 57.15 661.30 2077.54
24inch S5 2.30 inch 547 58.42 663.84 2085.51
24inch S5 2.35 inch 547 59.69 666.38 2093.49
24inch S5 2.40 inch 547 60.69 668.38 2099.78
24inch E6 20 mm 540 20.00 580.00 1822.12
24inch E6 23 mm 540 23.00 586.00 1840.97
24inch E6 25 mm 540 25.00 590.00 1853.54
24inch E6 28 mm 540 28.00 596.00 1872.39
24inch E6 32 mm 540 32.00 604.00 1897.52
24inch E6 35 mm 540 35.00 610.00 1916.37
24inch E6 38 mm 540 38.00 616.00 1935.22
24inch E6 44 mm 540 44.00 628.00 1972.92
24inch E6 50 mm 540 50.00 640.00 2010.62
24inch E6 56 mm 540 56.00 652.00 2048.32
24inch E6 1.00 inch 540 25.40 590.80 1856.05
24inch E6 1.25 inch 540 31.75 603.50 1895.95
24inch E6 1.5 inch 540 38.10 616.20 1935.85
24inch E6 1.75 inch 540 44.45 628.90 1975.75
24inch E6 1.90 inch 540 48.26 636.52 1999.69
24inch E6 1.95 inch 540 49.50 639.00 2007.48
24inch E6 2.00 inch 540 50.80 641.60 2015.65
24inch E6 2.10 inch 540 53.34 646.68 2031.61
24inch E6 2.125 inch 540 54.00 648.00 2035.75
24inch E6 2.20 inch 540 55.88 651.76 2047.56
24inch E6 2.25 inch 540 57.15 654.30 2055.54
24inch E6 2.30 inch 540 58.42 656.84 2063.52
24inch E6 2.35 inch 540 59.69 659.38 2071.50
24inch E6 2.40 inch 540 60.69 661.38 2077.79
24inch Terry 20 mm 520 20.00 560.00 1759.29
24inch Terry 23 mm 520 23.00 566.00 1778.14
24inch Terry 25 mm 520 25.00 570.00 1790.71
24inch Terry 28 mm 520 28.00 576.00 1809.56
24inch Terry 32 mm 520 32.00 584.00 1834.69
24inch Terry 35 mm 520 35.00 590.00 1853.54
24inch Terry 38 mm 520 38.00 596.00 1872.39
24inch Terry 44 mm 520 44.00 608.00 1910.09
24inch Terry 50 mm 520 50.00 620.00 1947.79
24inch Terry 56 mm 520 56.00 632.00 1985.49
24inch Terry 1.00 inch 520 25.40 570.80 1793.22
24inch Terry 1.25 inch 520 31.75 583.50 1833.12
24inch Terry 1.5 inch 520 38.10 596.20 1873.02
24inch Terry 1.75 inch 520 44.45 608.90 1912.92
24inch Terry 1.90 inch 520 48.26 616.52 1936.85
24inch Terry 1.95 inch 520 49.50 619.00 1944.65
24inch Terry 2.00 inch 520 50.80 621.60 1952.81
24inch Terry 2.10 inch 520 53.34 626.68 1968.77
24inch Terry 2.125 inch 520 54.00 628.00 1972.92
24inch Terry 2.20 inch 520 55.88 631.76 1984.73
24inch Terry 2.25 inch 520 57.15 634.30 1992.71
24inch Terry 2.30 inch 520 58.42 636.84 2000.69
24inch Terry 2.35 inch 520 59.69 639.38 2008.67
24inch Terry 2.40 inch 520 60.69 641.38 2014.95
20inch Recumbent 20 mm 451 20.00 491.00 1542.52
20inch Recumbent 23 mm 451 23.00 497.00 1561.37
20inch Recumbent 25 mm 451 25.00 501.00 1573.94
20inch Recumbent 28 mm 451 28.00 507.00 1592.79
20inch Recumbent 32 mm 451 32.00 515.00 1617.92
20inch Recumbent 35 mm 451 35.00 521.00 1636.77
20inch Recumbent 38 mm 451 38.00 527.00 1655.62
20inch Recumbent 44 mm 451 44.00 539.00 1693.32
20inch Recumbent 50 mm 451 50.00 551.00 1731.02
20inch Recumbent 56 mm 451 56.00 563.00 1768.72
20inch Recumbent 1.00 inch 451 25.40 501.80 1576.45
20inch Recumbent 1.25 inch 451 31.75 514.50 1616.35
20inch Recumbent 1.5 inch 451 38.10 527.20 1656.25
20inch Recumbent 1.75 inch 451 44.45 539.90 1696.15
20inch Recumbent 1.90 inch 451 48.26 547.52 1720.08
20inch Recumbent 1.95 inch 451 49.50 550.00 1727.88
20inch Recumbent 2.00 inch 451 50.80 552.60 1736.04
20inch Recumbent 2.10 inch 451 53.34 557.68 1752.00
20inch Recumbent 2.125 inch 451 54.00 559.00 1756.15
20inch Recumbent 2.20 inch 451 55.88 562.76 1767.96
20inch Recumbent 2.25 inch 451 57.15 565.30 1775.94
20inch Recumbent 2.30 inch 451 58.42 567.84 1783.92
20inch Recumbent 2.35 inch 451 59.69 570.38 1791.90
20inch Recumbent 2.40 inch 451 60.69 572.38 1798.18
20inch Schwinn 20 mm 419 20.00 459.00 1441.99
20inch Schwinn 23 mm 419 23.00 465.00 1460.84
20inch Schwinn 25 mm 419 25.00 469.00 1473.41
20inch Schwinn 28 mm 419 28.00 475.00 1492.26
20inch Schwinn 32 mm 419 32.00 483.00 1517.39
20inch Schwinn 35 mm 419 35.00 489.00 1536.24
20inch Schwinn 38 mm 419 38.00 495.00 1555.09
20inch Schwinn 44 mm 419 44.00 507.00 1592.79
20inch Schwinn 50 mm 419 50.00 519.00 1630.49
20inch Schwinn 56 mm 419 56.00 531.00 1668.19
20inch Schwinn 1.00 inch 419 25.40 469.80 1475.92
20inch Schwinn 1.25 inch 419 31.75 482.50 1515.82
20inch Schwinn 1.5 inch 419 38.10 495.20 1555.72
20inch Schwinn 1.75 inch 419 44.45 507.90 1595.61
20inch Schwinn 1.90 inch 419 48.26 515.52 1619.55
20inch Schwinn 1.95 inch 419 49.50 518.00 1627.34
20inch Schwinn 2.00 inch 419 50.80 520.60 1635.51
20inch Schwinn 2.10 inch 419 53.34 525.68 1651.47
20inch Schwinn 2.125 inch 419 54.00 527.00 1655.62
20inch Schwinn 2.20 inch 419 55.88 530.76 1667.43
20inch Schwinn 2.25 inch 419 57.15 533.30 1675.41
20inch Schwinn 2.30 inch 419 58.42 535.84 1683.39
20inch Schwinn 2.35 inch 419 59.69 538.38 1691.37
20inch Schwinn 2.40 inch 419 60.69 540.38 1697.65
20inch Recumbent 20 mm 406 20.00 446.00 1401.15
20inch Recumbent 23 mm 406 23.00 452.00 1420.00
20inch Recumbent 25 mm 406 25.00 456.00 1432.57
20inch Recumbent 28 mm 406 28.00 462.00 1451.42
20inch Recumbent 32 mm 406 32.00 470.00 1476.55
20inch Recumbent 35 mm 406 35.00 476.00 1495.40
20inch Recumbent 38 mm 406 38.00 482.00 1514.25
20inch Recumbent 44 mm 406 44.00 494.00 1551.95
20inch Recumbent 50 mm 406 50.00 506.00 1589.65
20inch Recumbent 56 mm 406 56.00 518.00 1627.34
20inch Recumbent 1.00 inch 406 25.40 456.80 1435.08
20inch Recumbent 1.25 inch 406 31.75 469.50 1474.98
20inch Recumbent 1.5 inch 406 38.10 482.20 1514.88
20inch Recumbent 1.75 inch 406 44.45 494.90 1554.77
20inch Recumbent 1.90 inch 406 48.26 502.52 1578.71
20inch Recumbent 1.95 inch 406 49.50 505.00 1586.50
20inch Recumbent 2.00 inch 406 50.80 507.60 1594.67
20inch Recumbent 2.10 inch 406 53.34 512.68 1610.63
20inch Recumbent 2.125 inch 406 54.00 514.00 1614.78
20inch Recumbent 2.20 inch 406 55.88 517.76 1626.59
20inch Recumbent 2.25 inch 406 57.15 520.30 1634.57
20inch Recumbent 2.30 inch 406 58.42 522.84 1642.55
20inch Recumbent 2.35 inch 406 59.69 525.38 1650.53
20inch Recumbent 2.40 inch 406 60.69 527.38 1656.81