Methodology

This page explains how Sauna in Japan collects, verifies, and updates the data shown across the site, including the figures published in our annual data report.

Data Sources

Sauna room temperatures, water bath temperatures, loyly availability, outdoor bath access, and tattoo policies are sourced from community-maintained Japanese databases, where facility details are reported and kept up to date by local sauna enthusiasts and the facilities themselves. Hotel names, locations, pricing, and guest review scores come from major international booking platforms.

What We Track

For every hotel we track six core attributes: sauna room temperature (°C), water bath temperature (°C), loyly availability (self-service or automatic), outdoor bath access, tattoo policy, and the lowest listed nightly rate. Coverage varies by attribute — not every facility publishes every specification. Where a value is unavailable, we show a dash (—) rather than estimating.

Prices

Prices shown are the lowest listed rate for a standard stay at the time of our most recent data refresh. They are indicative only — actual rates vary by date, room type, and availability. Always confirm the final price on the booking platform.

Review Scores

Review scores are guest ratings aggregated from major booking platforms. They reflect overall guest satisfaction with the hotel, not a rating of the sauna facilities specifically.

Tattoo Policies

Tattoo acceptance is recorded as reported at the time of collection. Policies can change without notice, and some facilities that accept tattoos may require cover stickers or private bathing. We strongly recommend confirming directly with the facility before booking.

Update Cycle

The dataset is refreshed periodically, and every aggregate figure on this site is recomputed automatically from the latest dataset at build time. Each facility page and the data report display the month of the most recent refresh.

Corrections

If you spot outdated or incorrect information, please let us know via our social media channels and we will review it promptly.

Citing Our Data

Journalists, bloggers, and researchers are welcome to cite our statistics with attribution and a link to sauna-in-japan.com. See the citation guide in our data report for a ready-to-use credit line.