Bolt Pattern Calculator

A wheel bolt pattern describes the arrangement of the lug holes that secure a wheel to a vehicle's hub. It is written as two numbers, such as 5x114.3, where the first number is the count of bolt holes and the second number is the Pitch Circle Diameter (PCD) in millimeters. The PCD is the diameter of the imaginary circle that passes through the center of every lug hole. This bolt pattern calculator turns physical measurements you take with a ruler or caliper into a precise PCD value, then matches that value against a database of common patterns so you instantly know whether a wheel will bolt up to your car.

Getting the bolt pattern right is the single most important fitment check when shopping for aftermarket wheels. A wheel with the wrong PCD simply will not seat against the hub face, no matter how attractive the offset or width may be. Because most modern PCDs are measured in metric units (100 mm, 108 mm, 112 mm, 114.3 mm, 120 mm, and so on), even a difference of a few millimeters separates two incompatible patterns. The calculator works entirely in millimeters internally and also reports the equivalent inch value, since classic American and truck applications such as 6x139.7 (often labeled 6x5.5") are still quoted in inches.

The calculator accepts the number of bolts and either a known PCD or a single center-to-center measurement between lug holes. From those inputs it reconstructs the full geometry of the bolt circle using basic trigonometry. Because the lug holes are spaced evenly around a circle, the angle between any two neighboring bolts is 360 degrees divided by the bolt count. Each bolt sits at the end of a radius, and the straight-line chord between two adjacent holes forms an isosceles triangle whose apex angle is that spacing angle.

From this triangle the tool derives the adjacent bolt distance (the chord you can measure between neighboring holes), the diagonal distance for four-bolt patterns, and the conversion of PCD into inches by dividing by 25.4. It also checks whether the wheel's center bore is larger than the vehicle's hub. When the wheel bore is bigger, the wheel is not hub-centric and the calculator flags that a hub centric ring is required to remove the gap and center the wheel properly.

Accurate measurement is what makes the PCD calculator useful. The reliable approach depends on whether your wheel has an even or odd number of bolts. For even bolt counts (4, 6, or 8 lugs), you can measure straight across from the center of one hole to the center of the hole directly opposite, and that distance equals the PCD. For odd bolt counts (5 lugs being the most common), there is no hole directly across, so you measure the adjacent center-to-center chord and let the calculator solve for PCD, or you measure from the back edge of one hole to the far edge of the second hole away.

The table below summarizes the geometric relationships the calculator uses for the most common bolt counts. The factor is sin(180°/n); multiply the PCD by it to get the adjacent chord, or divide the chord by it to recover PCD.

The bolt pattern alone does not guarantee a clean fitment. The center bore, also called the hub bore, is the large hole in the middle of the wheel that locates onto the raised hub of the vehicle. When the wheel's center bore matches the vehicle's hub diameter, the wheel is hub-centric and the hub itself carries the wheel's weight while centering it perfectly. This calculator compares the two values you enter and tells you whether a ring is needed.

Aftermarket wheels are usually made with an oversized bore so a single design fits many cars. When the wheel bore exceeds the hub diameter, you need a hub centric ring whose outer diameter equals the wheel bore and inner diameter equals the vehicle hub. For example, a wheel bored to 73.1 mm fitted to a hub measuring 67.1 mm needs a 73.1 mm OD / 67.1 mm ID ring. Skipping the ring forces the lug nuts alone to center the wheel, which can leave the assembly slightly off-center and produce a vibration that feels exactly like an out-of-balance tire. If the wheel bore is the same as or smaller than the hub, no ring is required and the calculator confirms the wheel is already hub-centric.

Most vehicles use one of a relatively small set of standard bolt patterns, which is why a bolt pattern calculator can match your measurement to a likely vehicle family. Knowing the popular patterns also helps you shop for wheels and understand cross-compatibility between brands. The list below covers the patterns this tool recognizes and typical models that use them.

Note that two patterns sharing the same bolt count and PCD are interchangeable, while a difference as small as 114.3 mm versus 120 mm makes the wheels incompatible. The calculator's match tolerance is half a millimeter, so a measured PCD within 0.5 mm of a known value is reported as a match.