Cycling Reference
700c Bicycle Tire (mm to inches)
700C is a nominal tire family. Common 700C tires use a 622 mm bead-seat diameter; inflated outside diameter depends on the tire, rim and pressure.
Maintained by mmtoinches.im · Updated
NIST describes the standard inch as exactly equivalent to 25.4 mm
. NIST length definition. Schwalbe — ETRTO and bicycle tire sizes. Method and limitations.
Convert 700c (ISO 622 mm BSD) to inches and estimate overall diameter based on tire width. See how it compares to 29er, 27.5, and 26 standards before selecting tires.
Key conversions
Bead seat diameter: 622 mm = 24.49 in
Overall diameter ≈ rim_diameter_in + 2 × (tire_width_mm ÷ 25.4)
Circumference ≈ π × overall_diameter_in
Detailed calculator
For precise fit, use the tire size calculator to compare two tires, check clearance, and estimate speedometer impact.
700c quick conversion & estimator
Estimate outside diameter and circumference by width, then search common 700c sizes.
Estimator (by width)
Outside diameter ≈ 26.69 in
Circumference ≈ 83.86 in (2130 mm)
Assumes tire height ≈ width. Measure mounted tires for clearance and calibration.
700c quick conversion table
| Label | Width (mm) | Outside (in) | Circ (in) | Circ (mm) | Rollout range (mm) | Notes |
|---|---|---|---|---|---|---|
| 20 | 26.06 | 81.89 | 2080 | 2070–2090 | Very narrow road; comfort limited; check pressure | |
| 22 | 26.22 | 82.39 | 2093 | 2080–2100 | Narrow road; may measure low height | |
| 23 | 26.30 | 82.67 | 2100 | 2090–2110 | Narrow road; casing/pressure can lower height | |
| 25 | 26.46 | 83.11 | 2111 | 2100–2125 | Common road width; measure for precise fit | |
| 26 | 26.54 | 83.36 | 2117 | 2105–2125 | Road; slightly taller than 25c | |
| 28 | 26.69 | 83.91 | 2131 | 2120–2145 | Versatile road/commute width | |
| 30 | 26.85 | 84.35 | 2142 | 2130–2150 | All-road; popular on modern rims | |
| 32 | 27.01 | 84.82 | 2155 | 2145–2165 | Comfort/commute/touring | |
| 33 | 27.09 | 85.08 | 2161 | 2150–2170 | CX/gravel; check clearance | |
| 35 | 27.24 | 85.54 | 2174 | 2165–2185 | Light gravel/utility | |
| 37 | 27.40 | 86.05 | 2186 | 2175–2195 | Gravel; stability improves with volume | |
| 38 | 27.48 | 86.35 | 2194 | 2185–2205 | Gravel; check fork/frame clearance | |
| 40 | 27.64 | 86.83 | 2206 | 2195–2215 | Gravel/adventure; fender clearance critical | |
| 42 | 27.80 | 87.33 | 2218 | 2205–2225 | Gravel/utility; fender clearance important | |
| 45 | 28.03 | 88.04 | 2237 | 2230–2250 | High-volume gravel; many frames cannot fit | |
| 47 | 28.19 | 88.56 | 2252 | 2240–2260 | High-volume; many frames cannot fit | |
| 50 | 28.43 | 89.27 | 2268 | 2260–2280 | Very high-volume; verify frame/fork limits |
Rim diameter: 622 mm (~24.49 in). Formula: outside_diameter_in ≈ (622 + 2×width_mm) ÷ 25.4; circumference_in ≈ π × outside_diameter_in.
Cyclocomputer calibration
Cyclocomputer calibration (700c)
Select your tire width to see typical circumference entry ranges. For best accuracy, roll out one wheel revolution and measure.
Reference: 2131 mm
Tip: Pressure and rider weight change rollout. Recheck after big tire swaps or pressure changes.
Rim internal width vs tire width
Rim internal width compatibility
Match rim inner width to tire width for safe casing support and predictable handling.
Selected tire is within recommended range.
Note: Wider rims can increase measured width and casing height. Always verify frame/fork/fender clearance.
| Rim IW (mm) | Tire range (mm) | Notes |
|---|---|---|
| 17 | 25–32 | Road focus; narrower tires may measure low height |
| 19 | 28–40 | Common all-road/commute range |
| 21 | 30–45 | Gravel-capable; verify frame/fork clearance |
| 23 | 32–50 | High volume; fenders/mud clearance become critical |
How 700c compares
29er (same rim diameter)
Shares the 622 mm BSD; overall diameter depends on tire height/width.
27.5" (ISO 584 mm)
Bead seat diameter ≈ 22.99 in; not compatible with 700c.
26" (ISO 559 mm)
Bead seat diameter ≈ 22.01 in; not compatible with 700c.
Scenario-based tire selection
Typical width: 23–28 mm
- Lower rolling resistance; comfort improves with 28 mm on modern rims.
- Check rim internal width; very narrow rims may under-measure casing height.
Use the tire size calculator to compare setups and validate clearances.
Open tire size calculatorNaming & standards explained
- ISO/ETRTO: 700c uses bead seat diameter 622 mm (rim diameter ≈ 24.49 in).
- “28 inch” is a legacy label commonly used for narrow road tires on 700c rims.
- “29 inch” refers to wider, taller tires on the same 622 mm rims (often MTB), yielding a bigger outside diameter.
- 650b (27.5): BSD 584 mm. Not compatible with 700c tires/rims.
- 650c: BSD 571 mm. Triathlon/track sizes; not compatible with 700c.
Clearance measurement guide
- Measure top clearance from tire to fork crown/frame bridge. Aim for ≥ 5 mm (more in muddy conditions).
- Measure side clearance at chainstays/seatstays and fork blades. Target ≥ 3 mm per side.
- With fenders installed, increase safety margins and check for debris accumulation.
- Validate with mounted tires at riding pressure; labeled widths can vary by brand and rim.
Frequently Asked Questions
No. The rim BSD is 622 mm (~24.49"), and outside diameter depends on tire width.
Approx 26.46" OD; ~2111 mm circumference. Measure mounted for accuracy.
No. 622 mm tires do not seat on 584 mm rims.
Wider rims can increase measured width and slightly increase casing height; check brand charts.
Aim for ≥ 5 mm at the top and ≥ 3 mm per side; more for muddy conditions.
Estimate and compare wheel sizes
Use the tire size calculator to compare two setups, then validate clearances on your frame and fork before riding.
Sources and calculation notes
700C is a nominal tire family. Common 700C tires use a 622 mm bead-seat diameter; inflated outside diameter depends on the tire, rim and pressure.
Method: Divide millimeters by 25.4 to obtain inches. The factor is exact; displayed decimal values are rounded. Fractional inches are rounded to the selected denominator.
Scope: Check the ETRTO marking on both tire and rim. Rollout measurements are preferable to a nominal estimate when calibrating a cyclocomputer.
Content maintained by mmtoinches.im. Updated and reference notes reviewed . How we calculate and present measurements. Sources support the stated definitions; examples and calculators are not certification of a product or compliance with a standard.