Culture

What is the Difference Between Sento and Onsen?

Both are traditional bathhouses, but they provide different experiences. Here’s a basic guide to sento and onsen—plus a word on their relationships with tattoos.

By Laura Payne Jan 4, 2024 4 min read 1

Japan’s centuries-old bathing culture is unique thanks to influences such as the country’s large number of natural hot springs, observations of the potential health benefits of mineral-rich baths and beliefs from Shinto and Buddhism—which associate bathing with cleansing the body and mind and gaining merit.

In modern Japan, hot baths are such a big part of everyday life that the Japanese language has multiple words to explain bathing experiences. Sento (public baths) and onsen (hot springs) are two examples that describe traditional communal baths. While sento and onsen are similar, each carries distinct differences.

If you want to experience Japan’s bathing culture, here is some basic information you should know beforehand.

Different Water Source

Sento also have a whole different vibe than traditional onsen.

Japan doesn’t mess around when it comes to onsen. They even have strict laws as outlined in the Hot Springs Act. To legally be called an onsen, a facility needs water as hot as 25 degrees Celsius and containing specified minerals.

Any facility using hot spring water that naturally meets these conditions is called a tennen onsen (natural onsen). Jinko onsen (man-made onsen) meet the conditions artificially—for instance, a spring may contain sufficient minerals but must be heated to 25 degrees. A sento simply needs heated tap water to fill their baths.

Different Purpose

Is it an onsen or a nice sento? It depends on the water.

Since the Heian Period (794–1185), sento have served as communal bathing and socializing spaces. This tradition persisted after World War II due to the lack of bathing facilities in many homes at that time.

However, as private baths in homes became commonplace, the number of sento dwindled. Despite this, laws like the Public Bath House Act officially recognize sento as essential for community health and hygiene. This recognition allowed many sento to remain open during Japan’s COVID-19 lockdown. In contrast, onsens are primarily destinations for leisure and relaxation. Typically located outside city centers, visitors travel to onsens for mineral baths, delectable food, and overnight stays.

The Public Bath House Act does not govern these facilities, thanks to the inclusion of accommodations and the unique composition of the onsen water. Moreover, “sento” usually refers to a specific facility, while “onsen” can encompass a single facility or an entire area. For instance, Tamayu in Shimane Prefecture features a neighborhood with multiple resorts, each housing an onsen facility. Collectively, they draw water from the same spring and are known as Tamatsukuri Onsen.

Different Prices

A private onsen in the countryside isn’t going to be cheap.

An onsen is going to be more expensive compared to sento. An onsen is a private business, and the owner determines admission. On the other hand, sento prices are regulated by the government, reflecting their status as public necessities. As of 2020, the maximum admission fee for adults at sento is 520 yen, making them an affordable option for daily bathing. This government regulation ensures accessibility to communal bathing facilities for the wider community.

However, there are exceptions to this rule. “Super sento,” classified as recreational facilities under the Public Bath House Act, are not subject to price regulation. An example is Spa World in Osaka, a super sento offering themed baths, swimming pools and activities like karaoke. Foot baths, ashiyu in Japanese, are another exception to the pricing norm. Typically found outdoors in onsen areas, ashiyu are usually free to use.

What About Tattoos?

Typical cute-but-strict signage banning tattoos in Japan.

In 2016, the Japan Tourism Agency officially encouraged bathing facilities to find ways for tattooed guests to enjoy the bathing culture. Many facilities have since adopted the agency’s suggestions, such as providing waterproof patches for guests to cover small tattoos. These encouragements aim to shift social perceptions and interpretations of the law rather than altering a specific legal provision.

The Public Bath House Act doesn’t explicitly prohibit tattooed visitors from sento; it only restricts those who may pose a public health risk, such as those with infectious diseases. Laws governing hotels and inns, often applied to onsen, allow for refusing guests engaging in illegal activities or disrupting public morals, but they don’t specifically address tattoos.

Traditionally associated with yakuza (organized crime members) in Japan, tattoos are often cited as a reason for barring visitors. Facilities, particularly recreational ones like onsen and super sento, justify these decisions by banning anyone who might make other visitors uncomfortable.

Nevertheless, sento, as public facilities, are far more likely to be less strict about tattoos than onsen. If you have tattoos and plan to visit an onsen, it’s crucial to check the specific policies of the facility beforehand. While some places are becoming more accepting, others may still enforce restrictions based on their rules or cultural considerations. To plan ahead, check out our list of the 30 best tattoo-friendly onsen in Japan.

What is your favorite sento or onsen? Do you know any good tattoo-friendly facilities? Let us know in the comments!