This tool will not guess your printer's hole offset for you
Plenty of generic advice recommends a default hole compensation value, but real hole offset varies by printer, nozzle, slicer, and even hole size. A default correction that happens to be wrong for your setup can make the fit worse than doing nothing at all. This tool applies your own measured offset directly if you have one, and if you do not, it proposes a calibration test rather than filling the gap with a guessed number.
How the compensation works
A measured offset is the difference between a hole's actual printed diameter and its nominal CAD diameter (positive if it prints larger, negative if smaller). Once you have that number from a test print, this tool subtracts it from your target diameter to tell you what to design at instead, so the printed result lands near your true target. Without a measured offset, the result routes you to a simple calibration print rather than assuming a value.
Worked example
A 6 mm target hole with a measured offset of +0.3 mm (holes print 0.3 mm larger than drawn): the tool recommends designing the hole at 5.70 mm so the printed result lands near 6 mm, and notes that this offset should be re-checked if you change nozzle, material, or hole orientation.
A common mistake
A frequent error is measuring a calibration offset once, months ago, and reusing it indefinitely. A nozzle swap, a slicer update, or a new filament brand can all shift this number without any obvious warning sign. If a part that used to fit suddenly does not, a stale offset is a more likely explanation than a mysterious new problem.
Limitations
This deliberately does not guess a default correction without a measurement. A wrong assumed offset can be worse than no compensation at all if it pushes the hole size the wrong direction; measure before you compensate.