Printable worksheet

← Back to the Ring Size Converter

10 problems20 problems

Include answer key

In the print window, choose “Save as PDF” as the printer (or print it on paper). Seed 1 rebuilds this exact sheet.

Ring Size worksheet

Grade 7 · CCSS 7.G.B.4

Solve each problem and show your work. Round answers to 2 decimal places where needed.

1.
Problem 1.
- What do you know?: EU / ISO size
- EU / ISO ring size: 55
Find: US / Canada size
Answer
2.
Problem 2.
- What do you know?: US / Canada size
- US / Canada ring size: 6
Find: US / Canada size
Answer
3.
Problem 3.
- What do you know?: Finger or ring circumference
- Measurement: 45 mm
Find: US / Canada size
Answer
4.
Problem 4.
- What do you know?: EU / ISO size
- EU / ISO ring size: 50
Find: US / Canada size
Answer
5.
Problem 5.
- What do you know?: Japanese size
- Japanese ring size: 12
Find: US / Canada size
Answer
6.
Problem 6.
- What do you know?: EU / ISO size
- EU / ISO ring size: 75
Find: US / Canada size
Answer
7.
Problem 7.
- What do you know?: Finger or ring circumference
- Measurement: 60 mm
Find: US / Canada size
Answer
8.
Problem 8.
- What do you know?: Finger or ring circumference
- Measurement: 44 mm
Find: US / Canada size
Answer
9.
Problem 9.
- What do you know?: EU / ISO size
- EU / ISO ring size: 45
Find: US / Canada size
Answer
10.
Problem 10.
- What do you know?: Japanese size
- Japanese ring size: 10
Find: US / Canada size
Answer

Answer key: Ring Size worksheet

1. US / Canada size: 7.25
1. An EU size is the distance around in mm, so divide by π (about 3.14) to get the width across
  $\frac{55}{π}$ $= 17.507044 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 17.507044$ $= 55 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{17.507044 - 11.63}{0.8128}$ $= 7.230615$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 7.25$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{55 - 37.5}{1.25}$ $= 14 steps → O$
2. US / Canada size: 6
1. Turn the US size into a width across: size 0 is 11.63 mm, and each size adds 0.8128 mm
  $11.63 + 0.8128 \times 6$ $= 16.5068 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 16.5068$ $= 51.857642 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{16.5068 - 11.63}{0.8128}$ $= 6$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 6$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{51.857642 - 37.5}{1.25}$ $= 11.49 steps → L½$
3. US / Canada size: 3.25
1. Find the width across the inside: divide the distance around by π (about 3.14)
  $\frac{45}{π}$ $= 14.323945 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 14.323945$ $= 45 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{14.323945 - 11.63}{0.8128}$ $= 3.314401$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 3.25$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{45 - 37.5}{1.25}$ $= 6 steps → G$
4. US / Canada size: 5.25
1. An EU size is the distance around in mm, so divide by π (about 3.14) to get the width across
  $\frac{50}{π}$ $= 15.915494 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 15.915494$ $= 50 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{15.915494 - 11.63}{0.8128}$ $= 5.272508$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 5.25$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{50 - 37.5}{1.25}$ $= 10 steps → K$
5. US / Canada size: 6.25
1. Turn the Japanese size into a width across: 12⅔ mm plus ⅓ mm for each size
  $\frac{38 + 12}{3}$ $= 16.666667 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 16.666667$ $= 52.359878 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{16.666667 - 11.63}{0.8128}$ $= 6.196686$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 6.25$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{52.359878 - 37.5}{1.25}$ $= 11.89 steps → M$
6. US / Canada size: 15
1. An EU size is the distance around in mm, so divide by π (about 3.14) to get the width across
  $\frac{75}{π}$ $= 23.873241 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 23.873241$ $= 75 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{23.873241 - 11.63}{0.8128}$ $= 15.063043$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 15$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{75 - 37.5}{1.25}$ $= 30 steps → Z+5$
7. US / Canada size: 9.25
1. Find the width across the inside: divide the distance around by π (about 3.14)
  $\frac{60}{π}$ $= 19.098593 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 19.098593$ $= 60 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{19.098593 - 11.63}{0.8128}$ $= 9.188722$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 9.25$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{60 - 37.5}{1.25}$ $= 18 steps → S$
8. US / Canada size: 3
1. Find the width across the inside: divide the distance around by π (about 3.14)
  $\frac{44}{π}$ $= 14.005635 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 14.005635$ $= 44 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{14.005635 - 11.63}{0.8128}$ $= 2.922779$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 3$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{44 - 37.5}{1.25}$ $= 5.2 steps → F$
9. US / Canada size: 3.25
1. An EU size is the distance around in mm, so divide by π (about 3.14) to get the width across
  $\frac{45}{π}$ $= 14.323945 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 14.323945$ $= 45 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{14.323945 - 11.63}{0.8128}$ $= 3.314401$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 3.25$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{45 - 37.5}{1.25}$ $= 6 steps → G$
10. US / Canada size: 5.5
1. Turn the Japanese size into a width across: 12⅔ mm plus ⅓ mm for each size
  $\frac{38 + 10}{3}$ $= 16 mm$
2. Find the distance around the inside: π × the width across. This is also the EU size
  $π \times 16$ $= 50.265482 mm$
3. Find the US size: take off the 11.63 mm of size 0, then count how many 0.8128 mm steps are left
  $\frac{16 - 11.63}{0.8128}$ $= 5.376476$
4. Round to the nearest quarter size, the finest step most US jewellers stock
  $nearest quarter size$ $= 5.5$
5. Find the UK letter: starting from A at 37.5 mm around, count one letter for every 1.25 mm
  $\frac{50.265482 - 37.5}{1.25}$ $= 10.21 steps → K$