この回線はどれくらい速い？
このサイトで唯一、自前のデータからは出せない測定です。回線の限界速度で実際にデータを流す必要があるためで、その部分は OpenSpeedTest が自社ネットワークで担当します。開始を押すまで、何も読み込まれず、先方へ何も届きません。
開始すると OpenSpeedTest のウィジェットが読み込まれます。以後、測定はあなたのブラウザと先方のサーバーの間で行われ、あなたのアドレスと通信量は先方から見えます。このサイトの他の機能はそうではありません。押さない限り、先方への通信は一切ありません。
テストが動く場所
速度テストは回線を数秒間いっぱいに使う必要があり、数千回ごとにテラバイト規模の通信になります。これを自前で背負えば、サイトの他の部分を無料に保っている費用を帯域に注ぐことになり、混んだサーバーはあなたではなく自分自身を測ることになります。OpenSpeedTest はオープンソースで商用利用も無料、まさにこのための回線を持っています。だからこの数字は先方のものであり、そのほうが正確です。ここの他のすべては、いまも自分たちで作ったデータから答えています。
A speed test moves data between your browser and a server and times it. The number it produces is the capacity of the path between those two points at that moment — not a property of your line, and not a promise about any other destination. The measurement here is run by OpenSpeedTest, on their network rather than ours.
What the three numbers mean
Download is how fast data reaches you, and it is the number that decides whether video buffers. Upload is how fast it leaves, which matters for video calls, backups and sending large files; on most cable and DSL lines it is a fraction of the download figure by design. Latency is how long a round trip takes, and it is what makes a connection feel quick or sluggish — for calls and games it matters far more than raw speed. Jitter is how much that round trip varies, and a high figure is what turns a call choppy even when the speed looks fine.
Why our number can differ from your provider's
A provider quotes the capacity of the line into your home. This test measures the whole path from your browser to the test server: your Wi-Fi, your router, everything else on the line, your provider's network, and the route out to the nearest OpenSpeedTest node. A result below the advertised figure usually means a bottleneck somewhere along that path rather than a fault on the line, which is why a wired test on an otherwise idle connection is the one worth comparing.
Why the test is not ours
Every other answer on this site is read from data we compile, on our own hardware, with nothing about your visit leaving it. A speed test cannot work that way: it has to saturate your line for several seconds, which is terabytes of traffic for every few thousand tests, and an origin busy serving that measures its own congestion as much as your connection. So this one page hands the measurement to OpenSpeedTest — open source, free for commercial use, and running a network built for it. The widget is not loaded until you press start, so their servers see nothing about a visitor who only reads the page.
よくある質問
Why is my speed lower than what I pay for?
Most often Wi-Fi, an older router, or something else on the line using it at the same time. Beyond your home, the path to any given server can be congested even when your line is not. Test over a cable with everything else idle, and compare a few servers before concluding the line is at fault.
Does a VPN slow the test down?
Almost always, yes. The traffic takes a detour through the VPN's exit server and is encrypted on the way, so both the speed and the latency you see belong to that path rather than to your own connection.
What is a good latency?
Under 30 ms is excellent for anything interactive, and under 60 ms is comfortable. Satellite links run into the hundreds and mobile networks vary with signal. Jitter above roughly 30 ms is what makes calls break up, even on a fast line.
Who sees my address when I run the test?
OpenSpeedTest does, once you start it — the bytes have to go somewhere, and they go to their servers. We do not record the result, do not receive it, and do not associate anything with your address; nothing is loaded from them at all until you press start. Reading this page without starting the test contacts no one but us.