What Is a PCD Calculator?
A PCD Calculator calculates the Pitch Circle Diameter of an equally spaced wheel bolt pattern. PCD is the diameter of the imaginary circle passing through the centers of the wheel's bolt holes or studs.
Wheel bolt patterns are commonly written using the number of bolts followed by the PCD. For example, 5×112 means five bolt positions arranged on a 112 mm diameter circle.
PCD Calculator Formula
When you know the center-to-center distance between two adjacent bolts, PCD can be calculated using the number of equally spaced bolts.
PCD = Adjacent Bolt Distance ÷ sin(180° ÷ Number of Bolts)
The formula treats the adjacent bolt measurement as a chord of the bolt circle. The number of equally spaced bolts determines the central angle between those bolt positions.
How to Use the PCD Calculator
Select Bolt Count
Choose the total number of equally spaced wheel bolts or stud holes.
Measure Adjacent Holes
Measure center-to-center between two neighboring bolt holes and select mm or inches.
Calculate PCD
Get the estimated pitch circle diameter and formatted wheel bolt pattern.
PCD Calculation Example
Suppose a wheel has five equally spaced bolt holes and the center-to-center distance between two adjacent holes is about 65.83 mm.
5-Bolt Example
The calculated bolt pattern is therefore approximately 5×112.
What Does PCD Mean on a Wheel?
PCD stands for Pitch Circle Diameter. It describes the diameter of the imaginary circle formed through the center points of equally spaced wheel bolt holes.
Bolt Count
The first part of a bolt pattern tells you how many wheel studs or bolt holes are arranged around the hub.
PCD Diameter
The second value is the diameter of the circle passing through the center of those bolt positions.
How to Read a Wheel Bolt Pattern
A bolt pattern such as 5×112 contains two main pieces of information. The number 5 means there are five bolt positions, while 112 means the pitch circle has a diameter of 112 millimeters.
Similarly, 4×100 represents four bolt positions on a 100 mm pitch circle, while 6×139.7 represents six bolt positions on a 139.7 mm pitch circle.
Common Wheel Bolt Patterns
Vehicles use many different bolt patterns. Examples you may encounter include:
- 4×100
- 5×100
- 5×112
- 5×114.3
- 5×120
- 6×139.7
- 8×165.1
These are examples only. The correct wheel specification depends on the specific vehicle, hub and wheel.
Why Accurate PCD Measurement Matters
Wheel PCD is one of several dimensions that must be compatible when checking wheel fitment. A similar-looking bolt pattern does not necessarily mean two wheels are interchangeable.
Accurate measurement helps identify the bolt-circle geometry, but wheel compatibility also involves other specifications.
Center Bore
The wheel's center bore and the vehicle hub dimensions can affect fitment.
Wheel Offset
Offset affects where the wheel sits relative to the hub, suspension and body.
Wheel Diameter & Width
Wheel dimensions must also be suitable for the vehicle and tire combination.
Fastener Specifications
Stud or bolt size, thread specification and seating type are separate from the PCD measurement.
This calculator determines geometric PCD from the measurements entered. PCD alone does not confirm that a wheel is suitable for a vehicle. Verify the vehicle and wheel manufacturer's specifications before selecting or installing wheels.
PCD in Millimeters vs Inches
Many wheel bolt patterns are specified in millimeters, but some applications use inches. This calculator accepts either unit and automatically displays the equivalent PCD in the other unit.
One inch equals exactly 25.4 millimeters, so the calculator uses that conversion when displaying both results.
Common PCD Measurement Mistakes
- Measuring from the outside edges of bolt holes instead of their centers.
- Entering the wrong number of wheel bolts.
- Mixing inches and millimeters.
- Measuring non-adjacent holes while using an adjacent-hole formula.
- Assuming PCD is the only measurement needed for wheel fitment.
PCD Calculator FAQs
PCD stands for Pitch Circle Diameter. On a wheel, it is the diameter of the imaginary circle passing through the centers of the equally spaced bolt holes.
Divide the adjacent center-to-center bolt distance by the sine of 180 degrees divided by the number of equally spaced bolts.
It means the wheel has five bolt positions arranged around a pitch circle that is 112 millimeters in diameter.
Yes. Select inches as the measurement unit. The calculator also shows the converted PCD in millimeters.
PCD is the pitch circle diameter portion of the wheel bolt pattern. A complete pattern normally includes both the number of bolt positions and the PCD, such as 5×112.
No. Wheel fitment also depends on specifications such as center bore, offset, wheel dimensions, fasteners and vehicle requirements.