UART baud rate calculator — bit & byte time
Work with serial timing: enter a baud rate and read bit time, byte time (8N1) and throughput — or solve the baud rate that fits a target byte rate.
Serial link
Timing & throughput
Bit time
1 ÷ baud
Bits per frame
1 start + 8 data + 0 parity + 1 stop
Byte time
Frame bits ÷ baud
Max bytes/s
Baud ÷ frame bits
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.
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Frequently asked questions
How do I convert UART baud rate to bytes per second?
Divide the baud rate by the number of bits per frame. An 8N1 frame is 10 bits (1 start, 8 data, 1 stop), so 115200 baud carries 115200 ÷ 10 = 11520 bytes per second.
What does 8N1 mean and why does it reduce serial throughput?
8N1 is shorthand for 8 data bits, no parity and 1 stop bit, which packs 10 bits into every frame and delivers only 8 payload bits. The byte rate is therefore exactly one tenth of the baud rate, and adding a parity bit makes each frame 11 bits.
How do I choose a baud rate for a target byte rate?
Multiply the required bytes per second by the frame bits: 11520 bytes/s × 10 bits = 115200 baud. The tool also reports the nearest standard rate from 9600 to 921600 and warns when it is more than about ±3% off, past the typical UART clock tolerance.
Ideal UART timing; real links add framing errors on noisy lines and jitter on clock mismatch. ICBOMS provides this tool for reference only.