This **circumference to diameter calculator** is an **essential tool** that helps convert the **diameter** of a circle when given its **circumference**.

A

circular pizza panwith acircumferenceof62.8 inches. To find itsdiameterusing ourcircumference to diameter converter, you would input62.8as the circumference. The calculator would then use theformula(explained later) to determine that the diameter is approximately20 inches.

## Circumference to Diameter Calculator

inches Circumference to | Diameter (inches) |
---|---|

1.0 in | 0.32 in |

1.5 in | 0.48 in |

2.0 in | 0.64 in |

2.5 in | 0.80 in |

3.0 in | 0.96 in |

3.5 in | 1.11 in |

4.0 in | 1.27 in |

4.5 in | 1.43 in |

5.0 in | 1.59 in |

5.5 in | 1.75 in |

6.0 in | 1.91 in |

6.5 in | 2.07 in |

7.0 in | 2.23 in |

7.5 in | 2.38 in |

8.0 in | 2.55 in |

8.5 in | 2.71 in |

9.0 in | 2.87 in |

9.5 in | 3.02 in |

10.0 in | 3.18 in |

10.5 in | 3.34 in |

11.0 in | 3.50 in |

11.5 in | 3.66 in |

12.0 in | 3.82 in |

12.5 in | 3.98 in |

13.0 in | 4.13 in |

13.5 in | 4.29 in |

14.0 in | 4.45 in |

14.5 in | 4.61 in |

15.0 in | 4.77 in |

15.5 in | 4.92 in |

16.0 in | 5.08 in |

16.5 in | 5.14 in |

17.0 in | 5.30 in |

17.5 in | 5.46 in |

18.0 in | 5.62 in |

18.5 in | 5.78 in |

19.0 in | 5.94 in |

19.5 in | 6.10 in |

20.0 in | 6.37 in |

## Circumference to Diameter Chart

Circumference (units) | Diameter (units) |
---|---|

5 | 1.59 |

10 | 3.18 |

15 | 4.77 |

20 | 6.37 |

25 | 7.96 |

30 | 9.55 |

35 | 11.14 |

40 | 12.74 |

50 | 15.92 |

60 | 19.10 |

70 | 22.00 |

75 | 23.87 |

80 | 25.46 |

90 | 28.65 |

100 | 31.83 |

120 | 38.20 |

150 | 47.74 |

200 | 63.66 |

250 | 79.25 |

300 | 95.49 |

## Circumference to Diameter Formula?

The formula to convert **circumference** to **diameter** is:

**D = C / π**

Where:

Dis thediameterCis thecircumferenceπ(pi) is approximately3.14159

This formula is derived from the well-known equation for the circumference of a circle: **C = πD**

If a circle has a

circumferenceof31.4 units: D =31.4 / π≈10 unitsFor a

circular poolwith a circumference of94.2 feet: D =94.2 / π≈30 feet

## How to Convert Circumference to Diameter?

**Measure the circumference**of the circular object**accurately**.**Divide the circumference by π**(3.14159).**Round the result**to the desired number of**decimal places**.

For **precise calculations**, use as many decimal places of π as possible, for most **practical applications**, using **3.14** is sufficient.

Let’s convert a **circumference** of **47.1 cm** to **diameter**.

- Circumference =
47.1 cm47.1 / π≈14.99 cm- Rounded to two decimal places, the
diameteris15.00 cm

## What is the Diameter of a 20 Circumference?

The **diameter** of a circle with a circumference of **20 units** is approximately **6.37 units**.

To find the **diameter** of a circle with a **circumference** of **20 units**:

- Apply the formula:
**D = C / π** - Substitute the known values:
**D = 20 / π** - Calculate:
**D ≈ 6.37 units**

This result can be verified by calculating the circumference using the found diameter: **C = πD = π * 6.37 ≈ 20 units**

# Is the Circumference 3.14 Times the Diameter?

**The circumference is π times the diameter.**

While π is often approximated as **3.14**, its actual value is an **irrational number** that continues infinitely without repeating. The first few digits are **3.14159265359…**

For everyday calculations, using **3.14** as an approximation for π is usually sufficient. However, in fields requiring **high precision**, such as **aerospace engineering** or **scientific research**, more decimal places of π are used.

**Example**: For a circle with a **diameter** of **10 units**:

- Approximate circumference:
**3.14 * 10 = 31.4 units** - More precise circumference:
**π * 10 ≈ 31.4159265359 units**

The difference is **small** but can be **significant** in certain applications.

## What is the Diameter of a 21 Inch Circumference?

The **diameter** of a circle with a **21-inch circumference** is approximately **6.68 inches**.

To find the **diameter** of a circle with a **21-inch circumference**:

- Use the formula:
**D = C / π** - Substitute the known circumference:
**D = 21 / π** - Calculate:
**D ≈ 6.68 inches**

To verify:

- Calculate the
**circumference**using this diameter:**C = πD** **C = π * 6.68 ≈ 20.99 inches**

The slight discrepancy (**20.99 vs 21**) is due to **rounding** in our calculations. Using more decimal places in π would yield a more **precise answer**.

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