Statistics & Probability

Instant, private, and free

Pie Chart Angle Calculator.

Calculate a sector angle from a part and total.

On-device calculationNo signup
01

Set your values

Results update as you type.

angleDegrees: 90

angleDegrees

90.000000
percentage: 25

percentage

25.000000

Results update automatically as you type.

Use Cases

Creating Pie Charts for Reports

When building a pie chart in spreadsheet software or manually, use this calculator to find the exact angle for each data slice.

Example: If sales are 120 units out of 400 total, the sector angle is 108°.

Educational Demonstrations

Teachers and students can use this tool to understand the relationship between data proportions and circle geometry.

Example: Show that a part of 50 out of 200 gives a 90° sector.

Frequently Asked Questions

How do I calculate a pie chart angle?
Enter the value for the sector (Part) and the total sum of all sectors (Total). The calculator divides Part by Total and multiplies by 360 degrees to give the sector angle.
What if my Total is zero?
If Total is zero, the calculator cannot compute an angle because division by zero is undefined. Ensure Total is greater than zero.
Can I use this for percentages?
Yes, if you have percentages, you can still use Part and Total. For example, if a sector is 25% of the whole, set Part=25 and Total=100 to get 90 degrees.

Tips & Common Mistakes

Tips

  • Ensure Part is less than or equal to Total; otherwise, the angle will exceed 360°, which is not valid for a pie chart.
  • Use the same units for Part and Total (e.g., both in dollars, both in counts) to get a meaningful ratio.
  • Double-check your Total includes all categories; missing any will skew the angles.
  • For quick mental checks, remember that 25% of the total corresponds to a 90° angle.

Common Mistakes to Avoid

  • Entering percentages directly as Part without adjusting Total to 100, leading to incorrect angles.
  • Using a Total of zero, which results in an error or undefined angle.
  • Forgetting to convert the result to degrees if your calculator is set to radians mode.

Last updated: August 13, 2026