Sphere surface areaRadius or diameter
Name: Date:
Find the surface area of each sphere. Use π = 3.14.
1 cm²
2 cm²
3 cm²
4 cm²
5 cm²
6 cm²
Surface area of a sphere worksheets
The surface area of a sphere is 4πr², and at π = 3.14 that is 12.56 times the radius squared. These free printable worksheets label some figures with a radius and some with a diameter, so the first step is always reading which one you were given.
Kid stuck on one? You don’t just get the sheet.
Surface area of a sphere
The answer key prints on a separate page.
What's on this sheet
The mistake that costs the most marks is not the formula, it is the label. A sphere 18 cm across has a radius of 9, and squaring 18 instead gives an answer four times too big. Circling the word radius or diameter before touching a calculator is a habit worth more than any amount of extra practice on the multiplication itself.
Why this sheet works
Squaring is the other half, and it is smaller trouble here than on the volume sheet: r² means r × r, not r × 2. Working the square out on its own line before multiplying keeps the two steps from running together. Then it is one multiplication — 4 × 3.14 is 12.56 every time, which a child who notices it only has to work out once for the whole page.
How this one works
One question from this sheet, worked through a step at a time.
Surface area of a sphere, radius 4 cm
radius: 4 cm
4 × 4=16
12.56 ×16=200.96
200.96 cm²
- The 4 cm marked here runs from the center to the surface, so it is already the radius — which is what the formula wants.
- Square the radius on a line of its own. r² means r × r, not r × 2: 4 × 4 = 16.
- Now four times π, times that: 4 × 3.14 is 12.56, and 12.56 × 16 = 200.96. Nothing to round — 12.56 times a whole number always lands on a whole number of hundredths.
- So the surface area is 200.96 square cm. Square, not cubic — a surface is skin rather than space, and the unit is the quickest way to notice you have answered the volume question instead.