Pitch circle diameter · Starting angle · Center X
Mistake: Changing units and assuming the entered numbers were converted.
Fix: Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
Archive · Free
Bolt circle coordinate planner
Generate numbered X/Y centers for evenly spaced holes, with a diagram and CSV.
This tool is archived. Recheck its method and dated data before use.
01Enter your values
Runs in your browserRuns offline in your browser. Once the page and required files have loaded, processing needs no internet.
02Bolt circle coordinate planner
Runs in your browser
How it works
Generate numbered X/Y centers for evenly spaced holes, with a diagram and CSV.
θᵢ = θ₀ ± i × 360°/n; Xᵢ = X₀ + D/2 × cos(θᵢ); Yᵢ = Y₀ + D/2 × sin(θᵢ)
Runs in your browser
Discovery source
Your data stays yours
Inputs are processed on this page and are never sent to a server.
About this tool
Use tool ↑Generate numbered X/Y centers for evenly spaced holes, with a diagram and CSV.
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center. All lengths are mm. Zero degrees points along +X; +Y points up. Coordinates use sine and cosine. This is geometry, not G-code, tolerances or structural approval.
- Enter your values
- Pitch circle diameter
- Hole count
- Starting angle
- Numbering direction
- Center X
- Center Y
- Calculation method
θᵢ = θ₀ ± i × 360°/n; Xᵢ = X₀ + D/2 × cos(θᵢ); Yᵢ = Y₀ + D/2 × sin(θᵢ)
- Example scenario · Result
90°
Calculation method
- For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
- All lengths are mm.
- Zero degrees points along +X; +Y points up.
- Coordinates use sine and cosine.
- This is geometry, not G-code, tolerances or structural approval.
θᵢ = θ₀ ± i × 360°/n; Xᵢ = X₀ + D/2 × cos(θᵢ); Yᵢ = Y₀ + D/2 × sin(θᵢ)
Bolt circle coordinate planner
- Pitch circle diameter
- 100 mm
- Hole count
- 4
- Starting angle
- 0 °
- Numbering direction
- Counterclockwise
- Center X
- 0 mm
- Center Y
- 0 mm
Result
90°
Frequently asked questions
Can I run this CSV on a machine?
No. These are hole-center coordinates only. Check the drawing, datum, units, clearances and machining program independently.
Where does my data go?
Calculations run on your device. Form inputs are not sent to a server.
Terms and definitions
Enter your values
- Measurement system
The initial choice follows your browser region. Your choice is remembered on this device. Gallons are US gallons. Switching units keeps your numbers unchanged and interprets them in the new unit.
Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
- Pitch circle diameter
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.001 · Maximum: 1000000 mm
- Hole count
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Enter a whole number; fractional counts are not valid.
Minimum: 2 · Maximum: 360
- Starting angle
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Enter a numerical value for this quantity. Use the unit shown beside this field. °
Minimum: -360 · Maximum: 360 °
- Numbering direction
Choose the mode that matches the data you entered.
Options: Counterclockwise · Clockwise
- Center X
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: -1000000 · Maximum: 1000000 mm
- Center Y
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: -1000000 · Maximum: 1000000 mm
Result
- Result
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center. All lengths are mm. Zero degrees points along +X; +Y points up. Coordinates use sine and cosine. This is geometry, not G-code, tolerances or structural approval.
Calculated from your entries using the method below.
- Hole count
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Calculated from your entries using the method below.
- Adjacent-hole chord
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Calculated from your entries using the method below.
- Number
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center. All lengths are mm. Zero degrees points along +X; +Y points up. Coordinates use sine and cosine. This is geometry, not G-code, tolerances or structural approval.
Calculated from your entries using the method below.
- Angle (°)
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center.
Calculated from your entries using the method below.
- X (mm)
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center. All lengths are mm. Zero degrees points along +X; +Y points up. Coordinates use sine and cosine. This is geometry, not G-code, tolerances or structural approval.
Calculated from your entries using the method below.
- Y (mm)
For machinists laying out a complete circle: enter diameter, hole count and starting angle; optionally move the center. All lengths are mm. Zero degrees points along +X; +Y points up. Coordinates use sine and cosine. This is geometry, not G-code, tolerances or structural approval.
Calculated from your entries using the method below.
Common mistakes and quick fixes
Can I run this CSV on a machine?
Mistake: Treating a result as valid outside the described scope.
Fix: No. These are hole-center coordinates only. Check the drawing, datum, units, clearances and machining program independently.
Limits and key assumptions
- No. These are hole-center coordinates only. Check the drawing, datum, units, clearances and machining program independently.
- This is geometry, not G-code, tolerances or structural approval.
- Displayed results may be rounded; rounding does not add measurement precision.