What is packet loss?

Short answer

Packet loss is the share of small data messages that never arrive. Many call and game services want it close to zero, because lost messages cause choppy audio and stutter. SpeedUp does not measure it, but a ping test can.

What it is

Everything you do online is sent as small packets. If a packet gets lost on the way, it has to be sent again or skipped. Web pages and downloads recover and just feel slower. Calls and games cannot wait, so you hear and see the gap.

Signs of packet loss

Robotic or choppy voices in calls.
Video that freezes or jumps.
Game characters that teleport or snap back.
A connection that seems fine on speed tests but fails in live use.

Common causes

Weak or crowded Wi-Fi.
A damaged or loose network cable.
An overloaded or failing router.
A faulty line or a problem at the provider.
Mobile data with a weak signal.

How to check it

On Windows, open Command Prompt and type ping -n 100 1.1.1.1. On a Mac, open Terminal and type ping -c 100 1.1.1.1.
At the end, read the line with Lost (Windows) or packet loss (Mac).
Run it on Wi-Fi, then on a cable. If loss only appears on Wi-Fi, the signal is the problem.

See how to check your ping for more detail.

How to reduce it

Use a cable, or move closer to the router.
Replace a suspect network cable.
Restart the router and update its firmware.
If it happens on a cable too, contact your provider and share your test results.

Packet loss, ping and jitter are different

Ping is how long a message takes. Jitter is how much that time varies. Packet loss is the share that never arrive. See ping vs latency for all the terms side by side.