Condom nominal width
Nominal width is the width of the condom in millimetres when it's laid flat: in other words, half its circumference.
How nominal width is measured
Lay the condom out unrolled, flat and loose, then measure across it with a ruler. The number you read off is the nominal width. To measure it, ISO 4074-3 hung the unrolled condom over a ruler's edge. Under the standard, the width measured this way may be off by 2 mm at most, in either direction.
Because Condoms sold in the EU must carry the nominal width on the pack, European brands (for example Mister Size, Ritex and Billy Boy) use it for their product names.
From girth to nominal width
You get the condom's circumference before stretching by multiplying Nominal width by two. A circumference slightly under yours is what ONE recommends, so the condom grips and stays put.
Your girth divided by pi is what Okamoto recommends. The calculator uses the Mister Size table, which pairs a 12 cm girth with 53 mm: a little snugger, because condoms stretch.
Girth to nominal width table
| Girth (cm) | Girth (in) | Width (mm) | Width (in) | Size |
|---|---|---|---|---|
| 9.5 to 9.9 | 3.74 to 3.9 | 47 | 1.85 | Extra small |
| 10 to 10.4 | 3.94 to 4.09 | 49 | 1.93 | Small |
| 10.5 to 11.9 | 4.13 to 4.69 | 53 | 2.09 | Regular |
| 12 to 13.4 | 4.72 to 5.28 | 57 | 2.24 | Large |
| 13.5 to 14.4 | 5.31 to 5.67 | 60 | 2.36 | XL |
| 14.5 to 15.4 | 5.71 to 6.06 | 64 | 2.52 | XXL |
| From 15.5 | From 6.1 | 69 | 2.72 | XXXL |
These sizes come from the table published by the condom brand Mister Size. Each row ends just before the next one starts, so every girth has one width. Their published table ends with the 69 mm row at 15.5 cm. If you measure well over 15.5 cm, look at the widest condoms too, up to 72 mm (MY.SIZE PRO 72).
Width, circumference and diameter
Instead of width, some charts list a condom diameter or a circumference. Width doubled gives you the circumference. A 53 mm condom has a diameter of about 34 mm, since diameter comes from circumference divided by pi. The size is the same, whichever of the three you use.
Sources
- Mister Size: the condom's Nominal width is half its circumference, taken at the narrowest spot.
- To measure width under ISO 4074-3, you hung the unrolled condom so it draped past the ruler's edge.
- ONE Condoms note that multiplying the nominal width by 2 gives an approximate condom circumference.
- Okamoto's guide says to take your girth and divide by pi (about 3.14) to find the nominal width.