Awards, Barometers

So-net, the best fixed Internet performances in Japan

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Press release

Barometer of fixed Internet connections  
Japan H2 2022 – H1 2023 

So-net provided the best broadband Internet performances in Japan during the last two semesters.

This study is based on tests carried out by users of the nPerf.com website in Japan and other websites that collaborate with nPerf and have installed our free speed test.

Between July 1st, 2022 and June 30th, 2023 we counted in Japan 59,143 tests.

The overall distribution of the tests per provider is as follows:

The nPerf study is based on thousands of tests carried out exclusively by the operators’ end customers, which makes it the “crowdsourced” study based on one of the largest panels of the country. These tests reflect the actual experience of the general public in Japan on the various Internet networks.


So-net won the Japanese broadband Internet race during the two last semesters. The company leads on all the KPIs, which means the fixed-line operator had the best download and upload speeds, and the best latency within the period, which ensures the top position with the best nPerf score in total (169,733 nPoints).

The highest speed is the best.

  • Download speed: indicates the amount of data your connection can receive in one second from the nPerf server. Surfing the Internet, listening to music or downloading large files require a good download speed. Download speed is measured in megabits per second (Mb/s).

With a very significant gap when it comes to download speed (305 Mb/s), the carrier does make the difference compared to its rivals, offering around 100 additional Mb/s than its closest competitor in this field: J:COM (205 Mb/s).

In any case, average performances of the Japanese providers on this field are quite high. The last position of this ranking is for SoftBank (124 Mb/s), which offers an average bitrate more than twice as slow than the leader.

So-net has also taken victory in the latency category (20.7 ms), which is 9 ms less than the last placed SoftBank (29 ms).

  • The latency indicates the delay a small packet of data needs to make a round-trip from your device to a server. It describes how responsive your connection is: the time between sending information and receiving it. The shorter the delay, the most reactive is your connection. Latency is measured in milliseconds (ms). 

au one net and NTT, in the battle for the second place.

Those ISP have done a good work throughout the period, and even if they finish around 20,000 nPoints under the leader, they will surely fight to be considered the main competitors for the leader. Their scores are tight (respectively 151,779 and 149,446 nPoints).

J:COM and SoftBank arrive last despite a good fight.

With less than 145,000 points each, the victory seems a bit far away for both of them and the gap too large to catch up with the others. Nevertheless, let’s reminder that the Japanese market offers very high performances when it comes to fixed-broadband Internet. They have both very good KPIs.


nPerf is a French company based in Lyon and with more than 10 years of experience in the Internet sector. nPerf uses a worldwide dedicated servers network, which is optimized to deliver enough bitrate to saturate your connection, so that we can measure its bitrate accurately.

nPerf speed test is compatible with all broadband and mobile connections: ADSL, VDSL, cable, optical fiber FTTH / FTTB, satellite, wifi, wimax, cellular 2G / 3G / 4G (LTE), 5G.

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