Reading C1 and C2
In common 45° chamfer notation, C1 has two 1 mm legs and C2 has two 2 mm legs. The inclined face is longer: approximately 1.414 mm for C1. Check the drawing's notes and dimensioning convention if its notation differs.
Chamfer calculator
Calculate 45° chamfers, C1 and C2 sizes, legs and face length. Enter a different angle and check radial or axial dimensions for CNC.
Chamfer
1What does the drawing dimension?
or load an example:
2Enter the measurements
3Result
Click a dimension to copy it
How to use this calculation
A dimension along a part face is different from the length of the inclined chamfer surface. Select a C size for a 45° chamfer, or supply a known leg and angle for another slope. Use the sketch to confirm which face defines the angle.
Worked example
Known measurements
C size = 1 mm · angle = 45°
Result
Leg A = 1 mm · leg B = 1 mm · face ≈ 1.414 mm
Do not confuse the inclined face with the C size. For depth with a conical tool, use countersink / Z.
Chamfers other than 45°
The calculator uses leg B = leg A · tan α and face = leg A / cos α. Angle α lies between the inclined face and leg A, as labelled in the sketch. If your drawing measures from the other face, use the complementary angle.
Applying the geometry on a lathe
The legs are geometric distances. A radial change becomes twice that amount in X when the lathe uses diameter programming. These results do not include tool nose radius compensation or a cutter's actual tip geometry; establish those references before programming.
Frequently asked questions
Does C1 mean a 1 mm inclined face?
For a usual 45° chamfer, no: it indicates a 1 mm leg. The inclined face is √2 mm, approximately 1.414 mm.
Can I use C notation for 30°?
Enter the leg and angle explicitly instead. Do not interpret a C callout without checking the drawing's convention.
Is the calculated leg an X diameter change?
The output is a length. Double a radial change when using an X axis programmed in diameters.
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