Bolt Pattern Measurement Calculator
On 4, 6 and 8-lug hubs the pattern is simply the distance between opposite studs. On 5-lug hubs there is no opposite stud, so you measure differently and convert. This bolt pattern measurement tool does the conversion and tells you which standard pattern you have — or when the measurement can't decide.
The three methods
- Adjacent studs (any lug count): center of one stud to center of the next. PCD = distance ÷ sin(180° ÷ lugs). For 5 lugs that is ×1.7013; for 6, ×2; for 4, ×1.414.
- Skip-one (5-lug shop method): from the far outer edge of one stud to the center of the stud two positions away. Old rule says that equals the PCD; it's actually off by a millimeter or two, which is enough to confuse 114.3 with 115 — this tool corrects for stud diameter.
- Opposite studs (4, 6, 8 lugs): center to center straight across. That is the PCD, no math.
Measurement accuracy questions
How accurate does a bolt pattern measurement have to be?
Within about 1 mm. 5x114.3 and 5x115 differ by 0.7 mm at the circle, which a tape measure cannot resolve, and bolting a wheel onto the wrong one of those two stresses every stud. Measure with a caliper where you can, and treat any result this tool flags as a look-alike as unconfirmed until you check it against the vehicle.
Why does the shop "outer edge to centre" trick give the wrong number?
Because it ignores stud diameter. The skip-one chord on a 5-lug hub is PCD x sin(72 degrees), and measuring from the far outer edge adds half a stud on top. The old rule treats that sum as the PCD, which overshoots by a millimetre or two, exactly enough to turn a 114.3 into a 115. This tool subtracts the stud radius instead of ignoring it.
What do I multiply adjacent studs by?
PCD = distance divided by sin(180 degrees / lugs), so the multiplier depends only on the lug count: 1.4142 for 4 lugs, 1.7013 for 5, 2.0000 for 6 and 2.6131 for 8. The widely quoted 1.7013 is the 5-lug case of that one formula, not a separate rule.
Should I measure the wheel or the hub?
Either, but the wheel is easier: lay it face down and measure the holes on the flat back, where no centre cap or lug pocket is in the way. On the vehicle, measure stud centres, not the nuts, and make sure the tape sits across the true centre of the circle.