CircumferenceRadius or diameter
Name: Date:
Find the circumference of each circle. Use π = 3.14.
1 cm
2 cm
3 cm
4 cm
5 cm
6 cm
7 cm
8 cm
Circumference of a circle worksheets
The circumference is the perimeter of a circle, and the whole difficulty is noticing which measurement you were handed. These free printable worksheets label either the radius or the diameter.
If they get stuck
Circumference of a circle
The answer key prints on a separate page.
What's on this sheet
The segment on the figure is not decoration. A spoke from the center is a radius and a chord across the middle is a diameter, and the number sits on the segment rather than off to one side, because a child who puts a diameter where the formula wants a radius gets an answer twice too large.
Why this sheet works
Circles are drawn from their true size rather than from the printed number. On a mixed sheet a circle labeled 20 as a diameter is genuinely half the size of one labeled 20 as a radius, so the picture and the number agree — which is the check a child needs when the two formulas start to blur.
How this one works
Circumference: circle marked 7 cm
- The 7 cm marked here goes right ACROSS the circle — it is the diameter, the whole way across, which is exactly what a circumference needs.
- Circumference is π × the whole way across — that is the diameter, 7.
- Then multiply by π: 7 × 3.14 = 21.98 cm. Slightly more than three times across — which is what π has always been.