Spike's Calculators

# Donut - Metric Calculate the area and perimeter of a donut shape.
This calculator uses metres for measurements.

Donut = a circle with a smaller circle centred inside ### Donut Area and Perimeter - Metric

Outer Diameter m
Inner Diameter m
Decimal Precision

#### Results:

Inner Area
Total Area (Donut + Inner)
###### Area of the Donut
Square Metres
Square Feet ft²
Square Inches in²
Metres m
Feet ft
Inches in
Metres m
Feet ft
Inches in

#### Calculation

1. outer diameter in metres
2. inner diameter in metres
3. decimal precision, the number of digits after the decimal point

#### Results

1. the inner area in square metres
2. total area (donut area plus inner area) in square metres
3. the area of the donut in square metres
4. the area in square feet
5. the area in square inches
6. the outer perimeter of the donut in metres
7. the outer perimeter in feet
8. the outer perimeter in inches
9. the inner perimeter of the donut in metres
10. the inner perimeter in feet
11. the inner perimeter in inches
##### Formula
```A = ta-ti
ta = 𝛑D²
ti = 𝛑d²
𝛑 = 3.14159265
PO = 𝛑D
PI = 𝛑d
PO the outer perimeter of the donut
PI the inner perimeter of the donut

```

##### Conversions
```one metre (m) = 3.28083989501312 feet (ft)
one metre (m) = 39.3700787401575 inches (in)
one square metre (m²) = 10.7639104167097 square feet (ft²)
one square metre (m²) = 1550.0031000062 square inches (in²)
```