Ring Blank Sizing Calculator
Calculate the exact blank length for any ring size
Standard US ring sizes (inner diameter in mm)
B&S/AWG gauge thickness
mm
Add 0.5mm to length if band is over 4mm wide
Adjust for edge cleanup and skill level
Results
Inner Diameter
17.35 mm
Metal Thickness
1.024 mm
Inner Circumference
54.51 mm
Ring Blank Length
57.73 mm
Ring Blank Length
2.27 in
How to Use This Calculator
- Select the ring size - Choose the US ring size or enter a custom inner diameter
- Choose metal gauge - Select the gauge of your metal stock or enter custom thickness
- Enter band width - Optional, but important for wide bands over 4mm
- Adjust pi multiplier - Start with 3.1416, increase for extra cleanup allowance
Ring Blank Formula
Blank Length = (Inner Diameter + Metal Thickness) x Pi
The formula accounts for the metal wrapping around the mandrel. The blank stretches to form the outer circumference while the inner diameter stays at your target size.
Tips for Accurate Sizing
- Test with scrap first - Different tools and techniques may require slight adjustments
- Wide bands need extra length - Add 0.5mm for bands over 4mm wide
- Account for finishing - Filing and sanding the ends removes material
- Keep notes - Track what pi multiplier works best with your setup
Did You Know?
- A size 7 ring has an inner circumference of about 54.4mm (2.14 inches).
- Gold is so malleable that one ounce can be stretched into a wire 50 miles long.
- Ring sizes originated in the 1740s, with each size representing 1/64 inch in diameter.