Sizing

What condom size do I need?

Condoms are sized by nominal width, not length, and a poor fit is the main reason they slip or break. One measurement and one slider gets you the right number, in centimetres or inches.

Calculator
11.7 cm
Flat width 59 mm. Your nominal width: 49–56 mm.
Standard stock is 52–54 mm, which is inside your range.

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How do condom sizes actually work?

The number on the box is the nominal width: the width of the condom laid flat, which is half its circumference. It is defined in ISO 4074, the international standard for latex condoms, and it is a width measure, not a length measure. Length varies little between brands and stretches to fit; width is what determines whether a condom stays on and stays comfortable.

A good fit is 5–20 % narrower than your own flat width, because latex needs slight tension to stay put. That is the entire calculation: flat width = girth in mm / 2, then range = flat / 1.2 to flat / 1.05.

Condom size chart

Condom widths are always given in millimetres, whichever unit you measure in. Standard stock in most shops is 52–54 mm nominal width, which fits a girth of roughly 11–13 cm (4.3–5.1 in). Specialist ranges run from about 45 mm to 69 mm, so nearly everyone can find a proper fit; most people have simply never checked.

Not sure of your girth? Wrap a soft tape, or a marked paper strip, around the thickest part of the erect shaft. Full steps are in the how to measure penis size guide.

Girth (cm / in) Flat width (mm) Snug (mm) Roomy (mm)
8 / 3.1 40 33 38
9 / 3.5 45 38 43
10 / 3.9 50 42 48
11 / 4.3 55 46 52
12 / 4.7 60 50 57
13 / 5.1 65 54 62
14 / 5.5 70 58 67
15 / 5.9 75 63 71
16 / 6.3 80 67 76

Why does fit matter?

Because failure rates follow fit. In a study of 436 men, those reporting ill-fitting condoms had 2.6 times the odds of breakage and 2.7 times the odds of slippage, and both partners reported less pleasure (Crosby et al. 2010). Too wide and it slips, which is a contraception failure, not a wardrobe issue. Too narrow and it hurts, tears more easily, and tends to come off mid-act, which amounts to the same failure. The fix costs nothing: read the number on the box.

Full citations for the sizing standard and the fit research are on the method and sources page.