UART baud rate calculator — bit & byte time

About the model

Every UART frame spends one bit on a start edge, then the data bits, an optional parity bit and the stop bits. 8N1 — 8 data, no parity, one stop — packs 10 bits into each frame, so its byte rate is exactly one tenth of the baud rate. The receiver resynchronises on the falling start edge and samples each bit mid-cell, which is why common MCU UARTs hold up against ±2–3% of clock error before sampling errors appear.

Baud is a symbol rate, not the data payload rate — parity and stop bits eat into the real throughput, so the byte rate above is what a 1-byte-per-9-bit DMA loop will actually push.