Before you buy wheels, a spare, or a set of wheel adapters, you need to know the bolt pattern of your car. Get it wrong and the wheel simply will not sit on the hub, however good the price. The pattern is written as two numbers — the number of lugs and the diameter, in millimeters or inches, of the circle through the center of the studs — for example 5×114.3 mm. Reading the number off a part list is easy; finding it on a car without documentation means measuring, and measuring is where people go wrong, because on a wheel with an odd number of studs no two studs sit directly opposite each other. This bolt pattern calculator does the trigonometry: give it the lug count and one honest measurement between two studs, and it returns the pitch circle diameter (PCD).
How to use the bolt pattern calculator
- Count the studs or lug nuts on one wheel and choose the number.
- Measure from the center of one stud to the center of the next one. With a caliper, measure the gap between the studs and add one stud diameter to get center-to-center; with a ruler, measure from the edge of a stud on one side to the matching edge of the next stud.
- Select which studs you measured — neighbors, one stud skipped, or opposite studs on an even pattern.
- Read the PCD. The label shows the pattern as lugs × millimeters, and the inch size is listed beside it.
Bolt pattern formula
d = measured center-to-center distance, n = number of studs, k = number of steps between the two studs measured
The studs sit at the corners of a regular polygon inscribed in the pitch circle. The distance between two corners k steps apart is a chord of that circle, and a chord equals PCD × sin(k × 180° ÷ n). Solving for PCD gives the formula above. For neighbors (k = 1) on a 5-lug wheel, the PCD is d ÷ sin 36° = d × 1.7013; for a 6-lug wheel the neighbor distance is exactly half the PCD, because the hexagon's side equals its radius. When n is even and k = n ÷ 2, the two studs are opposite each other and the chord is the PCD itself.
Worked example
A 5-lug wheel has a center-to-center distance between neighboring studs of 67.2 mm.
- Angle: 180° ÷ 5 = 36°, sin 36° = 0.5878.
- PCD = 67.2 ÷ 0.5878 = 114.3 mm, which is 4.50 in.
- Round to the nearest standard pattern: 114.3 mm, which is 4.5 in. The pattern is 5×114.3.
Neighbor and skip-one distances for common circles
These distances are computed from the formula, so you can check a measurement against the pattern you expect. Distances are center to center, in millimeters.
| Studs | PCD (mm) | Neighbor distance | Skip-one distance |
|---|---|---|---|
| 4 | 100 | 70.71 | — |
| 4 | 114.3 | 80.82 | — |
| 4 | 120 | 84.85 | — |
| 4 | 139.7 | 98.78 | — |
| 5 | 100 | 58.78 | 95.11 |
| 5 | 114.3 | 67.18 | 108.71 |
| 5 | 120 | 70.53 | 114.13 |
| 5 | 139.7 | 82.11 | 132.86 |
| 6 | 100 | 50.00 | 86.60 |
| 6 | 114.3 | 57.15 | 98.99 |
| 6 | 120 | 60.00 | 103.92 |
| 6 | 139.7 | 69.85 | 120.98 |
| 8 | 100 | 38.27 | 70.71 |
| 8 | 114.3 | 43.74 | 80.82 |
| 8 | 120 | 45.92 | 84.85 |
| 8 | 139.7 | 53.46 | 98.78 |
Inch patterns converted
Imperial patterns are the inch size multiplied by 25.4, which is the exact definition of an inch.
| Studs | PCD (in) | PCD (mm) | Pattern in mm |
|---|---|---|---|
| 4 | 4 in | 101.6 mm | 4 × 101.6 mm |
| 4 | 4.25 in | 107.9 mm | 4 × 107.9 mm |
| 4 | 4.5 in | 114.3 mm | 4 × 114.3 mm |
| 5 | 4.25 in | 107.9 mm | 5 × 107.9 mm |
| 5 | 4.5 in | 114.3 mm | 5 × 114.3 mm |
| 5 | 4.75 in | 120.6 mm | 5 × 120.6 mm |
| 5 | 5 in | 127.0 mm | 5 × 127.0 mm |
| 5 | 5.5 in | 139.7 mm | 5 × 139.7 mm |
| 6 | 5.5 in | 139.7 mm | 6 × 139.7 mm |
| 6 | 6 in | 152.4 mm | 6 × 152.4 mm |
| 8 | 6.5 in | 165.1 mm | 8 × 165.1 mm |
Mistakes to avoid
- Measuring edge to edge on one stud and center on the other. Use matching points on both studs.
- Counting the hub, not the wheel. The pattern comes from the hub studs or the holes in the wheel; both must match.
- Trusting a match that is a millimeter off. A wheel that is close but wrong may appear to bolt up, then loosen. If your reading falls between two standards, measure again.
- Ignoring the other fitment numbers. The bolt pattern is only the first check; confirm center bore, offset with the wheel offset calculator, and tire size with the tire size calculator.
Frequently asked questions
What is a bolt pattern?
A bolt pattern (also called lug pattern or PCD, pitch circle diameter) describes how many wheel studs there are and the diameter of the imaginary circle that passes through the center of every stud. A 5×114.3 mm pattern has five studs on a circle 114.3 mm (4.5 in) across.
How do I measure a 5-lug wheel?
The studs are not directly across from each other, so measure from the center of one stud to the center of a neighboring stud and enter that with 5 lugs. For a quick check, measure from the center of one stud to the center of the stud two places over, and choose “skipping one stud”. The calculator converts either number to the PCD.
Why is my result not exactly 114.3 or 120?
Hand measurements with a ruler are off by a fraction of a millimeter. Round the result to the nearest standard value; wheel patterns are defined by whole or standard decimal sizes such as 100, 108, 112, 114.3 and 120 mm. If your result lands between two standards, measure again with calipers.
Are inch and millimeter patterns interchangeable?
Only when the numbers match closely. Imperial patterns are the inch size × 25.4, so 4.5 in is exactly 114.3 mm. A 4.5 in pattern fits a 114.3 mm hub, but 4.5 in is not the same as 115 mm, and a wheel that is close but not equal can seat badly and loosen. Match the pattern, the center bore and the lug seat type.
Does the bolt pattern guarantee a wheel will fit?
No. You also need the right center bore, offset, wheel width and clearance for the brakes and suspension. Check offset with the Wheel Offset Calculator and overall tire diameter with the Tire Size Calculator.