Small • Standard • L Size • Large • Width & Diameter
Use this Condom Size Chart Japan to understand how Japanese condom sizing works across brands such as Okamoto and Sagami. Japanese domestic manufacturers often publish a 直径 — diameter measurement, while international condom charts frequently use nominal width. This guide keeps those measurements separate so you can compare small, standard, L-size and extra-large condoms without confusing diameter, flat width or penis girth.
Diameter and nominal lay-flat width are different measurements. Do not compare a Japanese 36 mm diameter specification directly with a 36 mm nominal-width condom.
Japanese condom manufacturers use size labels such as 小さめ for smaller products, スタンダード for standard options and Lサイズ or 大きめ for larger products.
The important detail is that Japanese domestic product pages may publish diameter rather than nominal lay-flat width.
| Japanese Product | Market Size Description | Published Measurement | Length | Measurement Type |
|---|---|---|---|---|
| Okamoto Smart Boy | Smaller / 小さめ | 31 mm | Product-specific | Manufacturer-stated diameter |
| Okamoto Standard Reference | Standard | 33 mm | Varies by product | Manufacturer comparison diameter |
| Sagami Original 0.01 | Standard | 36 mm | 170 mm | Diameter |
| Sagami Original 0.02 | Standard | 36 mm | 170 mm | Diameter |
| Okamoto Super Big Boy | Large / 大きめ | 37 mm | Product-specific | Diameter |
| Sagami Original 0.02 L | L Size | 38 mm | 190 mm | Diameter |
| Okamoto Mega Big Boy | Extra Large | Maximum 46 mm | Product-specific | Maximum diameter |
This is the most important part of a Japan condom size chart.
On CondomChart.com, most international size pages use nominal width: the side-to-side width of the condom while it is laid flat.
Japanese manufacturer pages may instead describe a product by 直径, meaning diameter.
Condom is flattened and measured from one side to the other. Common international examples include 49, 52, 54, 56, 58 and 60 mm.
Japanese product specifications may describe the approximate circular diameter of the condom or a particular section of the condom.
The full circumference around the erect penis. This is a body measurement, not a condom width number.
Measured separately. Sagami, for example, publishes both diameter and length for its Original line.
Okamoto's Japanese size-series information provides a particularly clear example of how domestic Japanese sizing can be presented.
Its size comparison uses diameter measurements.
| Okamoto Size | Published Diameter | Difference From Okamoto Standard Reference | General Position |
|---|---|---|---|
| Smart Boy | 31 mm | 2 mm smaller | Small / slimmer |
| Okamoto Standard Reference | 33 mm | Reference | Standard |
| Super Big Boy | 37 mm | 4 mm larger | Large / roomy |
| Mega Big Boy | Maximum 46 mm | Substantially larger | Extra-large shaped option |
Sagami's current Japanese Original product pages publish both length and diameter, making the Standard-versus-L difference easy to see.
| Sagami Product | Material | Published Diameter | Published Length | Size |
|---|---|---|---|---|
| Sagami Original 0.01 | Polyurethane | 36 mm | 170 mm | Standard |
| Sagami Original 0.02 | Polyurethane | 36 mm | 170 mm | Standard |
| Sagami Original 0.02 L | Polyurethane | 38 mm | 190 mm | L Size |
The L version is therefore both wider by the manufacturer's diameter measurement and longer than the standard version.
If you are in Japan but comparing imported condoms—or a Japanese-made product whose international listing uses nominal width—the following chart provides a separate nominal-width reference.
| Nominal Width | Flat Width Inches | Broad Comparison | Important Note |
|---|---|---|---|
| 45 mm | 1.77" | Extra snug | Nominal width, not Japanese diameter |
| 49 mm | 1.93" | Snug | Nominal width |
| 52 mm | 2.05" | Close / mainstream example | Nominal width |
| 54 mm | 2.13" | Regular example | Nominal width |
| 56 mm | 2.20" | Roomier | Nominal width |
| 58 mm | 2.28" | Large / wide | Nominal width |
| 60 mm | 2.36" | Wide | Nominal width |
| 64 mm | 2.52" | Extra wide | Nominal width |
Some international official listings for Japanese-made Okamoto products use the nominal-width system familiar to global condom shoppers.
Two millimetre numbers can look comparable while describing completely different condom geometry.
A Japan-market listing may publish 直径, while an international product chart may publish nominal flat width.
You do not need to estimate your condom size from nationality, height or where you live.
Whether you live in Tokyo, Osaka, Kyoto, Yokohama, Sapporo, Fukuoka or elsewhere in Japan, measure your own body.
Continue with How to Choose Condom Size by Measurement .
Japanese brands may market a narrower product using terms such as 小さめ, meaning smaller-sized.
Okamoto Smart Boy is a current clear example. Okamoto describes it as having a 31 mm diameter compared with the company's 33 mm standard reference.
This shows that Japanese “small” sizing may be expressed using diameter, rather than the 45–49 mm nominal-width numbers often seen in international size charts.
Do not compare 31 mm and 49 mm directly without accounting for the different measurement methods.
For international narrow widths, see Small Condom Size Chart .
Japan does not have one single product dimension that every manufacturer must market as “standard”.
Even major Japanese manufacturers publish different measurement systems and different product specifications.
Okamoto's Japanese size-series comparison uses 33 mm as its standard diameter reference.
Sagami Original 0.01 and 0.02 Standard are currently listed at 36 mm diameter and 170 mm length.
An international Japanese-made Okamoto product, meanwhile, may be listed with a 52 ±2 mm nominal width.
Lサイズ is commonly used in Japan to identify a larger condom within a particular product range.
But L does not correspond to one universal diameter or nominal width.
For example, Sagami Original 0.02 L is currently listed at 38 mm diameter and 190 mm length.
Okamoto offers multiple L-size products across its Zero One, Zero Two and 003 ranges.
The practical lesson is simple: treat “L” as a product category and check the technical specification before assuming its exact dimensions.
Okamoto's domestic size-series page gives a straightforward comparison.
| Measurement | Smart Boy | Okamoto Standard Reference |
|---|---|---|
| Published Diameter | 31 mm | 33 mm |
| Difference | 2 mm narrower by diameter | Reference |
| Position | 小さめ / smaller | Standard |
If a standard product repeatedly feels loose, this type of smaller category may be worth comparing.
Super Big Boy is part of Okamoto's larger domestic size range.
It is currently described as having a 37 mm diameter, four millimetres greater than Okamoto's 33 mm standard comparison reference.
The manufacturer positions it as a roomier large-size option.
Again, 37 mm here is a diameter specification—not a 37 mm international nominal-width measurement.
Mega Big Boy moves beyond Super Big Boy in Okamoto's size series.
Okamoto currently describes it as reaching a maximum diameter of 46 mm.
The word “maximum” matters because shaped condoms can have different dimensions at different points.
A maximum body diameter should therefore not be treated as a uniform base measurement or nominal width.
| Measurement | Sagami Original Standard | Sagami Original 0.02 L | Difference |
|---|---|---|---|
| Diameter | 36 mm | 38 mm | +2 mm |
| Length | 170 mm | 190 mm | +20 mm |
| Material | Polyurethane | Polyurethane | Same material family |
This comparison demonstrates that Japan-market L sizing can alter both width and length together.
It is not accurate to say that every condom sold in Japan is inherently smaller.
Japan has narrow products, standard products, L sizes and extra-large products.
Okamoto itself sells a size series ranging from the smaller Smart Boy to Super Big Boy and Mega Big Boy, while Sagami offers both standard and L-size Original products.
Japanese-made condoms are also sold internationally with nominal widths such as 52 ±2 mm and 56 ±2 mm.
A 52 mm nominal-width condom measures approximately 2.05 inches across when laid flat.
Some official international listings of Japanese-made Okamoto products use approximately 52 ±2 mm nominal width.
This does not contradict Okamoto Japan's domestic diameter references; it reflects a different measurement description.
Always read the unit and measurement type before comparing specifications.
56 mm nominal width equals approximately 2.20 inches when flat.
Okamoto's official international product listings include larger Japanese-made polyurethane options around 56 ±2 mm nominal width.
That places them above common 52 mm international-width references.
For cross-brand sizing, see Large Condom Size Chart .
Imported and specialist condom ranges may extend beyond common 52–56 mm nominal-width products.
For international nominal-width comparison:
These nominal-width values should not be compared directly with Okamoto or Sagami diameter numbers.
Read What Does 58mm Condom Mean? or 60mm Condom Size for dedicated guides.
Moving from a standard option to an L-size or roomier product can be worth comparing when a smaller product is consistently uncomfortable.
A wider product is not automatically more comfortable if it compromises secure fit.
Japan is well known for both latex and polyurethane condoms.
Sagami Original is made from polyurethane, while Okamoto offers both latex and polyurethane product families.
Material can influence stretch, feel and how a given size behaves.
That means two products with similar dimensional specifications may not feel identical.
When comparing Japanese condoms, look at:
They represent different measurements and should not be treated as the same size.
Japanese manufacturers sell small, standard, large and extra-large products.
L-size dimensions differ by manufacturer and product family.
Sagami Standard and L demonstrate that length can change substantially with the size category.
Penis girth is full body circumference and should be measured separately.
Living in Japan does not determine which condom width fits your body.
Japanese product specifications can change. Check the current manufacturer page or packaging before purchasing based on an exact diameter, width or length.
Common questions about Japanese condom sizes, Okamoto, Sagami, diameter, nominal width, small sizes, standard condoms, L-size condoms and measuring for proper fit.