Bolt Pattern Calculator: Find Wheel PCD and Fit

A bolt pattern calculator finds a wheel’s bolt-circle diameter (PCD) from the number of lug holes and a measured distance between holes. Enter the hole count and the distance in millimetres or inches; the calculator returns the PCD in the same unit, helping you compare wheel patterns before checking full vehicle fitment.

Formula

For equally spaced lug holes, the bolt-circle diameter is the distance between the centers of two adjacent holes divided by the sine of half the angle between neighboring holes:

PCD = d ÷ sin(180° ÷ n)

• PCD is the diameter of the circle passing through the centers of all lug holes, in millimetres or inches.
• d is the center-to-center distance between adjacent holes, in the same unit as the desired PCD.
• n is the number of equally spaced holes. The angle between adjacent holes is 360° ÷ n, so half that angle is 180° ÷ n.

The calculator takes the entered distance in millimetres and converts the answer to inches using 25.4 mm per inch. Its inch output is a conversion, not a separate measurement. The formula assumes the lug holes lie evenly around a circle, as wheel bolt patterns do.

Worked Example

With the calculator’s default values, there are five holes and the measured adjacent-hole distance is 70.5 mm.

1. Find half the angle between neighboring holes: 180° ÷ 5 = 36°.
2. Calculate sin(36°), approximately 0.587785.
3. Divide the measured distance by that value: 70.5 ÷ 0.587785 ≈ 119.94 mm.
4. Round to two decimal places: the PCD is 119.94 mm.
5. Convert to inches: 119.94 ÷ 25.4 ≈ 4.72 in.

The first result is the calculator’s headline answer. In wheel listings, this value would ordinarily be described using a nominal pattern such as 5×120 mm; the measured result should be compared with a reliable wheel or vehicle specification rather than treated as proof of fit.

What a Bolt Pattern Means

A wheel bolt pattern, also called a lug pattern or PCD, describes two things: the number of mounting holes and the diameter of the circle through their centers. A pattern written as 5×114.3 means five holes on a 114.3 mm bolt circle. The same PCD with a different number of holes is a different pattern: 4×100 and 5×100 are not interchangeable merely because both have a 100 mm circle diameter.

PCD is only one part of wheel fitment. Wheel diameter and width, offset, center bore, fastener type and seat, brake clearance, and the vehicle’s required load capacity also matter. A correct bolt pattern does not by itself show that a wheel is safe or suitable for a particular vehicle.

How to Measure the Hole Spacing

Measure from the center of one lug hole to the center of the next. Measuring consistently is important: measuring from hole edges, or mixing a center point with an edge, gives the wrong input. A ruler or caliper can help, but small measurement errors can become more noticeable when converted to PCD.

For an even number of holes, measuring between the centers of two holes directly opposite each other gives the PCD itself; no calculator conversion is needed. For an odd number of holes, there is no directly opposite pair. Measure between adjacent hole centers and use the formula, or consult a pattern chart with the vehicle or wheel specification.

For example, on a five-hole wheel, the adjacent-hole distance is not the PCD. Plugging that distance directly into a listing as the bolt-circle diameter would produce a substantially smaller and incorrect figure. Use the actual center-to-center measurement, and avoid rounding it before calculating.

When to Use the Calculator

• Identifying an unmarked wheel: Measure its hole count and spacing to estimate the PCD, then verify the result against dependable specifications.
• Comparing a wheel listing: Check that both the hole count and PCD match the vehicle’s stated requirement.
• Converting units: Read the equivalent result in millimetres and inches without manually converting the PCD.

Use the calculator when the hole count and measurement are known, not as a substitute for looking up a vehicle’s specified pattern. A rounded measurement can appear close to more than one nominal size. If the result is uncertain, remeasure or have the wheel identified accurately before attempting installation.

Common Errors and Limits

• Entering the wrong distance: The calculator requires adjacent-hole center-to-center spacing for its formula. It does not accept the distance between opposite holes as though it were an adjacent-hole measurement.
• Using the wrong hole count: Count the wheel’s mounting holes, not the number of studs on another component or the number of spokes.
• Mixing units: Enter a measurement in millimetres to get the displayed millimetre and inch results. If measuring in inches, convert that measurement to millimetres first: 1 in = 25.4 mm.
• Relying on rounded numbers: The calculator displays two decimal places, while manufacturer specifications often use familiar nominal values. Compare unrounded measurements where possible and verify the exact specification.
• Assuming a matching PCD guarantees fit: It does not check offset, center bore, fasteners, clearance, or load rating. Never force a wheel onto studs or use unsuitable hardware to compensate for a mismatch.

The calculation is geometric and assumes evenly spaced holes. It cannot correct a poor measurement, identify a damaged or modified wheel, or determine whether a particular combination meets vehicle requirements. For installation, use the vehicle and wheel maker’s specifications for compatible hardware and tightening procedure.

Frequently Asked Questions

How do I calculate a five-lug bolt pattern?
For five equally spaced holes, measure between the centers of adjacent holes and divide that distance by sin(36°). The result is the PCD. Alternatively, use a pattern chart or a purpose-made measuring tool and verify the specification.

Can I measure a five-lug pattern across opposite holes?
No pair of holes on a five-lug pattern is directly opposite, so an across-the-center measurement is not the PCD. Use adjacent-hole spacing with the formula or a reliable measuring method for odd-numbered patterns.

Is bolt pattern the same as PCD?
Not exactly. PCD is the bolt-circle diameter; a complete bolt-pattern description includes both the number of holes and the PCD, such as 5×114.3 mm.

Can a 5×114.3 wheel fit a 5×112 vehicle?
Those are different PCDs. Do not assume they are interchangeable or force the wheel into place. Confirm compatibility with vehicle and wheel specifications, including the appropriate mounting hardware and all other fitment requirements.

Does a matching bolt pattern mean the wheel will fit?
No. The PCD is only one fitment dimension. Center bore, offset, width, diameter, brake clearance, fasteners, and load capacity also need to be appropriate for the vehicle.

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in n | Lug-hole count | - | 5 | 3
in d | Distance between adjacent hole centers | mm | 70.5 | 0
out pcd | Bolt-circle diameter (PCD) | mm | d / sind(180 / n) | 2
out pcd_in | Bolt-circle diameter (PCD) | in | (d / sind(180 / n)) / 25.4 | 2