What Is Packet Loss?
Packet loss is when data packets sent across a network never reach their destination. Because the internet breaks every transfer into small packets, losing some means retransmissions, delay, and — in real-time apps — visible glitches.
How packet loss happens
Packets get dropped whenever something along the path can't deliver them:
- Congestion — a link or router is saturated and drops packets it can't queue.
- Faulty hardware — a failing NIC, cable, or router port.
- Wireless interference — weak Wi-Fi signal, contention, or noise.
- Overloaded server — the destination itself is too busy to accept traffic.
- Rate limiting / policing — intentional drops when traffic exceeds a threshold.
How it shows up
For file downloads, TCP quietly retransmits lost packets, so you mostly notice it as slower throughput. For real-time traffic — video calls, gaming, VoIP — there's no time to retransmit, so loss becomes stutter, frozen video, robotic audio, and rubber-banding.
What counts as acceptable
- 0% — ideal, expected on a healthy wired path.
- Under 1% — generally fine; most apps absorb it.
- 1–2.5% — noticeable in calls and games.
- Above 2.5% — a real problem worth investigating.
Measuring and narrowing it down
A ping test sends a series of ICMP echoes and reports the percentage that came back — that percentage is your packet loss. Testing from several locations tells you whether loss is near the destination (all locations see it) or specific to one route (only some do).
To find where loss starts, a traceroute-style hop-by-hop test shows the first hop where packets begin disappearing. Loss that only appears at the final hop often means the destination server, not the path.
Frequently asked questions
Is some packet loss normal?
Occasional loss under about 1% is normal and unnoticeable for most uses. Sustained loss above that, especially on a wired connection, points to a real fault worth chasing.
Does high ping mean packet loss?
No. Latency (ping time) and packet loss are separate. A path can have high latency with zero loss, or low latency with heavy loss. A ping test reports both.