Will My Smartphone Work in Japan? The Ultimate eSIM & SIM Card Guide for Travelers

Travelers visiting Japan often want to purchase a SIM card or eSIM to stay connected. Many inquire about whether their smartphones will work in Japan. To help you determine whether your smartphone can connect to Japan's mobile networks, we have summarized Japan's communication frequencies below.

Technical Requirements for Smartphones to Work in Japan

Certain technical requirements must be met for a smartphone to function in Japan.

1. SIM Lock-Free

Your smartphone must not be SIM-locked by a mobile carrier.

2. Compatibility with Japanese Frequencies

Your smartphone must support Japan’s frequency bands. If you plan to use an eSIM in Japan, your device must be eSIM-compatible. Many eSIM-compatible smartphones support Japan's frequency bands. To check whether your smartphone supports eSIM, refer to the following link: How to Quickly Check if Your Smartphone Can Use a Japanese eSIM

Japan’s Mobile Frequencies

Many travelers ask whether their smartphones support Japanese frequencies and whether they can connect in rural areas. Below is a frequency band table categorized by Japan’s major mobile carriers.

Japan 5G Frequency

Japan’s 5G network is divided into two categories:

• Sub6: Frequencies below 6GHz, offering strong obstacle penetration.
• Millimeter Wave: Frequencies between 30GHz and 300GHz (Japan primarily uses the 28GHz band) with ultra-fast speeds.

* A technology that repurposes existing 4G (LTE) networks for 5G use. The connection speed is approximately the same as 4G.

Japan 4G Frequency Number Support Table

Ensuring Stable Connectivity in Japan with SIM Cards or eSIMs

Many travelers hope to experience high-speed 5G in Japan. However, even in 2025, 5G coverage is still limited, and in many cases, the displayed "5G" signal is actually using a repurposed 4G network.

5G SIM Cards and eSIMs Often Provide Similar Speeds to 4G

Even if your smartphone displays "5G," it may be operating on a technology derived from 4G, resulting in similar speeds. Since 4G in Japan is stable and fast, most users will not experience issues using 4G. 5G-compatible SIM cards and eSIMs tend to be more expensive, but given the current limited coverage, a 4G-compatible SIM or eSIM is sufficient.

5G Coverage is Limited

True high-speed 5G connectivity is only available in specific areas, and few smartphones fully support it. Reliable 4G connectivity is sufficient.

iPhone 16 Series in Japan Does Not Support 5G Millimeter Wave

The iPhone 16 series sold in Japan does not support 5G millimeter waves. This further limits the availability of high-speed 5G connections.

Only Three Frequency Bands Are Essential for Connectivity in Japan

Rather than chasing high-speed connectivity, ensuring stable communication during your stay is crucial. Your smartphone should support Japan’s key 4G frequency bands.

For docomo Users, These Three 4G Bands Are Sufficient

Many SIM card and eSIM providers use docomo’s network, Japan’s largest carrier with the widest coverage. Travel Mobile, for example, uses docomo’s network. Docomo primarily operates on Band 1, Band 3, and Band 19. If your smartphone supports these bands, you can expect stable connectivity.

Checking Your Smartphone’s Frequency Compatibility

Most smartphone manufacturers provide specifications on their official websites, making it easy to check supported frequency bands.

Pocket WiFi Offers Stable and Fast Connectivity

If your smartphone does not fully support Japanese frequencies, you may experience connectivity issues. In such cases, renting a Pocket WiFi device ensures stable and high-speed connectivity.

Conclusion

To connect in Japan, ensure the following:

• Your smartphone is SIM-unlocked.
• It supports key Japanese 4G frequencies (especially Band 1, Band 3, and Band 19).
• 5G coverage is limited, so a 4G-compatible SIM or eSIM is sufficient.