Work out bit error rate instantly with clear inputs, formula shown and shareable results.
Bit error rate is errors divided by bits transmitted, and it converts to frame loss through 1 - (1 - BER)^(frame bits): a BER of 10^-12 corrupts about one frame in 83 million at 1500 bytes. Verifying a low BER takes a long time — at 10 Gbps, confirming 10^-12 with reasonable confidence needs several minutes of error-free transmission.
BER and frame loss
BER = bit errors / bits sent; frame error rate = 1 - (1 - BER)^(frame bytes x 8); test time for k errors = k / (BER x line rate)
10^-12 or better for most copper and optical variants. Some long-reach optical standards specify 10^-13 before forward error correction.
It corrects a bounded number of errors per block, converting a raw BER of around 10^-5 into a post-FEC rate well below 10^-15, which is how 400G optics work at all.