# Internet Speed Test

> Measure your connection in the browser: latency, jitter, download and upload speed. Powered by M-Lab's open NDT7 measurement network.

Canonical: https://host-tools.com/tools/internet-speed-test/

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## What this tool measures

Four numbers, and they answer different questions:

- **Download** — how fast data comes to you, in megabits per second (Mbps). It is what streaming,
  downloads and most browsing depend on.
- **Upload** — how fast data leaves you, in Mbps. It matters for video calls, backups and sending
  large files.
- **Latency** — the round-trip time to the measurement server, in milliseconds (ms). Lower is
  better; it is what makes a connection feel responsive.
- **Jitter** — how much that latency varies from moment to moment, in ms. High jitter is what
  makes a call stutter even when the bandwidth is fine.

## How the measurement works

The test uses **NDT7**, the open protocol from [M-Lab](https://www.measurementlab.net/). NDT7 is the
same measurement standard used in published internet research, so the numbers are comparable with
data collected elsewhere — not a private scale invented for one site.

Your browser asks M-Lab for the nearest measurement server, opens a WebSocket to it and transfers
data for about ten seconds in each direction. Everything happens on your device: no part of the
test goes through our servers. That matters, because a test served from a single small server
measures that server's bandwidth as soon as your connection is faster than it is.

Latency and jitter are read from the TCP connection that is actually moving the data, not from a
separate ping. That is the latency your transfers really experienced.

## Privacy: the one tool here that sends data to a third party

Every other tool on this site processes everything in your browser and sends nothing. This one is
different, and we would rather say so plainly:

**M-Lab collects the measurements — including your IP address — and publishes them as open data for
research.** That is the point of M-Lab: an open, public dataset about internet performance. Before
the test starts you are asked to accept
[M-Lab's data policy](https://www.measurementlab.net/privacy/), and the test does not run until you
do.

To show the network you are on, the tool also reads your approximate connection details (IP,
network/ASN and city) from Cloudflare's public metadata endpoint. Requests are not stored by us.

If you do not want your IP published as part of an open dataset, do not run this test — every other
tool on the site keeps everything local.

## Why the result can differ from other speed tests

A speed test measures the slowest point on the path, and every provider chooses a different path and
a different server. Expect variation between tests, and treat the numbers as a range rather than an
exact figure.

Things that move the result:

- **Wi-Fi vs cable.** Wi-Fi interference alone can halve a connection.
- **How busy the network is.** Neighbours, other devices in your home and peak hours all count.
- **Your device.** An old laptop or a busy browser cannot always keep up with a fast line.
- **The route to the server.** Distance and congestion between you and the measurement point.

Run the test a couple of times, at different moments, before drawing conclusions.

## Latency, bandwidth and what you actually need

Bandwidth and latency are not the same thing, and buying more of one does not fix the other. A
connection with 500 Mbps and 120 ms of latency will feel worse for a video call than a 100 Mbps line
with 15 ms. If calls freeze but downloads fly, the problem is latency or jitter, not bandwidth.

If the site you are testing looks unreachable, the [Website Status Checker](/tools/website-status/)
tells you whether the server is down or whether something on the way is blocking you.