What is packet loss?

Acutis · plain-English network help · updated June 2026

Packet loss, in plain English

Everything you send over the internet — a video call, a game move, a web page — is chopped into thousands of tiny chunks called packets. Each one travels separately and is reassembled at the other end. Packet loss is when some of those chunks never arrive. They get dropped somewhere along the way and have to be sent again, or are simply gone for good.

It's measured as a percentage: out of every 100 packets you send, how many go missing. Zero is ideal. Even 1–2% loss is enough to make a call stutter or a game rubber-band, and anything above 5% feels genuinely broken. The frustrating part is that packet loss is invisible to a normal speed test — your download number can look great while packets quietly vanish.

Why packet loss hurts more than low speed

People naturally blame "slow internet," but for real-time activities, dropped packets are usually the bigger villain. Here's why:

• Calls and video. Voice and video are live — there's no time to resend a lost packet, so the missing audio just becomes a gap. That's the robotic, choppy, "you cut out" effect, even on a fast connection.
• Gaming. A lost packet means your move or an enemy's position never registers. The game guesses, then snaps you to the correct spot when the next packet arrives — the dreaded rubber-banding and teleporting, regardless of how high your download speed is.
• Streaming and downloads. These can resend lost packets, so you rarely see errors, but every retransmission adds delay and forces lower video quality or buffering. The pipe is fast; it's just leaking.

The key idea: bandwidth is how wide the road is; packet loss is potholes in it. A wide road full of potholes still gives a rough ride.

What causes packet loss

Most packet loss starts inside your own home, which is good news — that's the part you can fix. Typical causes, roughly in order of how common they are:

• Wi-Fi interference and weak signal. Walls, distance, microwaves, and crowded channels in apartments all corrupt wireless packets so they have to be dropped. This is the number-one cause for most people.
• A bad or loose cable. A cheap, kinked, or damaged Ethernet cable — or a poorly seated connector — drops packets intermittently. Swapping the cable is a five-second test that often fixes it.
• Network congestion. Too much traffic at once — a 4K stream, a cloud backup, and a game all sharing the line — overflows your router's buffers and packets get discarded.
• An overloaded or aging router. Old or overheating routers, or ones running too many connected devices, start dropping packets under load. A reboot helps temporarily; a replacement helps permanently.
• Your ISP or the path beyond your home. A faulty line, a problem at the provider, or congestion several hops out can introduce loss you can't fix yourself — but you can prove it's not your equipment.

How to detect packet loss

You can't fix what you can't see, so the first step is measuring it. A ping test sends a stream of packets to a server and reports how many come back — the gap is your loss. Run it for at least 30 seconds so brief drops show up. Watch two numbers together:

• Packet loss % — anything above 0% on a wired connection is worth investigating; under 1% on Wi-Fi is usually tolerable.
• Jitter — how much your ping bounces around. High jitter often travels with packet loss and ruins calls in the same way.

Run the test once over Wi-Fi and once plugged in with Ethernet. If the loss disappears on the cable, the culprit is your wireless. If it persists everywhere, look at your cable, router, or ISP.

How to fix packet loss

Once you've confirmed loss, work through these in order — cheapest and most likely first:

1. Switch to Ethernet if you can. A wired link removes Wi-Fi interference entirely and is the single biggest fix for most people.
2. Improve the Wi-Fi if you can't go wired: move closer to the router, use the 5GHz band, and change to a less crowded channel.
3. Swap the cable and re-seat both ends. A bad cable is cheap to rule out and a surprisingly common cause.
4. Reduce congestion — pause cloud backups, big downloads, and other devices' streaming while you're on a call or in a game.
5. Reboot the router, and if loss returns under load on old hardware, consider replacing it.
6. If loss persists everywhere, with nothing else running and a fresh cable, the problem is likely your ISP or the path beyond your home — and that's the evidence you need to call them.