👤 By whycalculator Team 📅 Last Updated April 09, 2026
mm to Degree Calculator
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Are you looking to convert arc length or deflection into degrees? This mm-to-degree calculator will help you to calculate the angle by entering the arc length and radius. You can easily switch between different units like mm, cm, feet, and inches. Input your values, hit calculate, and get the results instantly!
How to Convert MM to Degree?
To convert millimeters (mm) to degrees, first calculate the angle subtended by an arc at the center of a circle. It can be found using the arc length and the radius of the circle. The relationship between arc length, radius, and angle (in degrees) follows a simple formula:
Formula:
θ = (L/2πR) × 360
Where:
- θ = Angle in degrees
- L = Arc length in mm
- R = Radius in mm
Example:

Arc length (L): 50 mm
Radius (R): 100 mm
θ = (L/2πR) × 360
θ = (50/2π×100) × 360 = 28.65°
This means a 50 mm arc on a 100 mm radius circle subtends an angle of approximately 28.65 degrees at the center.
How to Convert mm to Degrees (using radians)?
When dealing with circles, angles can also be measured in radians. To convert arc length to degrees, first calculate the angle in radians and then convert it to degrees.
Formula (Radians to Degrees):
θ = L/R
Where:
- θ = Angle in radians
- L = Arc length
- R = Radius
To convert radians to degrees:
θ = θ × 180/π
Example 1:
Arc length (L): 75 mm
Radius (R): 150 mm
Calculate in radians:
θ = 75/150 = 0.5 radians
Convert to degrees:
0.5 × 180/π = 28.65°
| Arc Length (mm) | Radius (mm) | Angle (Degrees) |
|---|---|---|
| 10 | 100 | 5.73° |
| 20 | 100 | 11.46° |
| 30 | 100 | 17.19° |
| 40 | 100 | 22.92° |
| 50 | 100 | 28.65° |
| 60 | 100 | 34.38° |
| 70 | 100 | 40.11° |
| 80 | 100 | 45.84° |
| 90 | 100 | 51.57° |
| 100 | 100 | 57.30° |
| 110 | 100 | 63.03° |
| 120 | 100 | 68.76° |
FAQs:
Can I convert mm to degrees without knowing the radius?
No, the radius is essential for the conversion because the relationship between arc length and angle depends on the circle's size.
What is the angle in degrees for 50 mm arc length and 200 mm radius?
Using the formula:
θ = (50/2π × 200) × 360 ≈ 14.32°
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