Calculate the packet loss percentage from sent and received packet counts.
Packet loss occurs when packets sent across a network fail to reach their destination, typically due to congestion, faulty hardware, or wireless interference. It is calculated as the percentage of sent packets that were not received. Even small amounts of packet loss (1-2%) can noticeably degrade real-time applications like VoIP calls and video conferencing, since lost packets can't simply be retransmitted in time.
Packet loss percentage
loss% = (sent − received) / sent × 100
Generally, under 1% packet loss is considered acceptable for most applications. VoIP and video conferencing start to show noticeable quality degradation above roughly 1-2% loss, and become largely unusable above 5%.
Common causes include network congestion, insufficient bandwidth, faulty cables or hardware, wireless interference, software bugs on network devices, and overloaded routers dropping packets when their buffers are full.
Latency measures how long a packet takes to arrive; packet loss measures whether it arrives at all. High latency with low loss means things are slow but reliable, while high loss means data is actually being dropped.
Tools like ping and mtr send a known number of packets and count how many responses come back, reporting the loss percentage. Continuous monitoring tools track this over time to catch intermittent issues.