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Condom Size Calculator

Turn a girth measurement into the nominal width printed on the box, in millimetres, plus the nearest stock sizes and a length check. Enter centimetres or inches, then press Calculate.

Written and reviewed by SM Arijul Islam · Last reviewed 6 November 2026 · Editorial standards · Report an error

Nominal width, not "large" or "XL"

Condom packaging carries a number in millimetres: 49, 52, 54, 56, 60. That is the nominal width, defined by the international standard ISO 4074 as the condom's lay-flat width at its narrowest point, measured between 20 and 50 mm from the open end. Because a flat condom has two layers across its width, the number is roughly half the circumference it is built for, and the standard allows each condom to sit within ±2 mm of the figure on the box.

Shop labels such as "regular", "large" or "extra large" are marketing, and they differ between brands — a "large" from one manufacturer can be a 54 mm, from another a 57 mm. The millimetre number is the only figure that means the same thing everywhere.

How to measure girth

Measure while erect, which is the state the condom has to fit.
Wrap a soft tape around the middle of the shaft — not the base, not the head, and not over the foreskin ridge.
Keep the tape snug but not compressing; read the circumference where it meets itself.
No tape measure? Wrap a strip of paper, mark the overlap, and lay it against a ruler.
Take two or three readings on different days; a few millimetres of variation is normal.

Girth to nominal width

Girth mapped to condom nominal width and the usual shop band
Girth	In inches	Nominal width	Usual band
Under 100 mm	Under 3.9 in	41 – 45 mm	Snug / small
100 – 109 mm	3.9 – 4.3 in	45 – 49 mm	Snug / small
110 – 119 mm	4.3 – 4.7 in	50 – 54 mm	Standard
120 – 129 mm	4.7 – 5.1 in	54 – 58 mm	Large
130 – 139 mm	5.1 – 5.5 in	59 – 63 mm	Large / extra large
140 – 149 mm	5.5 – 5.9 in	63 – 67 mm	Extra large
150 mm and up	5.9 in and up	67 – 69 mm	XXL

The ranges overlap on purpose. Latex stretches by roughly 10% to 15%, so neighbouring widths both fit the same person; the table is a starting point, not a prescription.

Worked example

A girth of 120 mm is a little over 4.7 inches. Half of 120 mm is 60 mm, and taking off a tenth for stretch gives about 54 mm, so the box to look for is 54 mm or the 56 mm beside it. A 110 mm girth lands at roughly 50 mm, and a 135 mm girth at about 61 mm — a 60 mm or a 64 mm condom. Below about 100 mm the choice narrows to the snug sizes in the 45 to 49 mm range, which are sold as "tight" or "extra tight" rather than by a letter.

What length changes

Width decides whether a condom stays on and feels right; length decides whether it rolls all the way down. ISO 4074 requires a minimum length of 160 mm, and most condoms are 180 to 205 mm with unused length left rolled at the base. A length under about 12 cm makes no difference at all to the choice, and only a length above roughly 20 cm usually justifies hunting for longer condoms — a long condom that is too wide will still slip.

Frequently asked questions

What is nominal width?

Nominal width is the condom measured flat, in millimetres, at its narrowest point. It is the number printed on the box and is roughly half of the girth the condom is made to fit.

How do I measure girth?

Wrap a soft tape measure around the shaft while erect, at the widest point but not over the base or the head, and read the circumference. A strip of paper marked and laid flat against a ruler works too.

Does length matter for condom size?

Much less than width. Condoms are made at least 160 mm long and typical ones are 180 to 205 mm, and unused length simply stays rolled at the base. Only a length well above 20 cm usually justifies a longer condom.

Why do two brands with the same nominal width feel different?

Nominal width describes one point on the condom, while shape, wall thickness, material and lubrication all change how it feels. Latex also stretches, so a condom a few millimetres narrower still fits.

Is a size calculator reliable?

It gives a starting point, not a guarantee. Measurement error and natural variation are larger than the gaps between sizes, so try the calculated width and the one above it before settling on a box.

Troubleshooting a fit

A condom that bunches into folds or slides off is too wide — drop 2 mm.
A condom that pinches, leaves a deep ring or is hard to unroll is too narrow — go up 2 mm.
A condom that will not stay rolled at the base is more often a length issue than a width one.
Slippage after a few minutes of use usually means the width is too large, not that the condom is faulty.

Common mistakes to avoid

Buying by the label. "Large" is not standardised; the millimetre width is.
Measuring flaccid. Girth while erect is what the condom has to fit.
Measuring over the widest point at the base, which overstates the width needed.
Assuming a bigger condom is safer or more comfortable. A loose condom is more likely to slip off.

Sources and limits

The nominal width definition, its ±2 mm tolerance and the minimum length come from ISO 4074, the international standard for natural rubber latex male condoms. The stretch allowance used here is the common rule of thumb in condom sizing: nominal width around half the measured girth, less roughly a tenth. It is an estimate — no calculator can account for differences in shape, erection firmness or the properties of a specific product.