Baud Rate Calculator

The baud is named after French engineer Émile Baudot, who in 1874 invented the 5-bit Baudot code used in early telegraphy — the first character encoding to use fixed-length binary codes rather than variable-length Morse. Teleprinters running Baudot code operated at 50 baud (about 50 words per minute for skilled operators), a rate that persisted in telex networks for a century.

The modern distinction between baud (symbols/second) and bps (bits/second) became important with the modems of the 1960s-80s. Bell 103 modems (1962) used 300 baud FSK with 1 bit/symbol = 300 bps. Bell 212A (1976) used 600 baud DPSK with 2 bits/symbol = 1200 bps. V.32 (1984) used 2400 baud TCM with 4 bits/symbol = 9600 bps. Modern V.90 modems (1998) hit 56 kbps using 8000 baud with 7 bits/symbol.

UART still uses 1 bit per symbol so baud = bps, but the standard 8N1 framing (1 start bit + 8 data + 1 stop = 10 bits per byte) makes char/sec = bps / 10. Classic 9600 baud means 960 char/sec; 115200 baud (the near-universal modern default) gives 11,520 char/sec. High-speed UARTs hit 921600 and even 3 Mbps (on FTDI chips), though cable length and crystal accuracy become limiting factors above ~1 Mbps.

Enter baud rate (symbols per second), bits per symbol (1 for UART, 4 for 16-QAM, 6 for 64-QAM, 8 for 256-QAM, etc.), and frame bits (10 for UART 8N1, 11 for 8N2, 12 for 8E1 with parity and 2 stops). The tool returns bit rate = baud × bits/symbol, character rate = bits/frame_bits, bit time = 1/bit_rate, and efficiency = payload/frame × 100% (80% for 8N1).

Keep in mind that receiver clocks must match the transmitter's baud rate to within ~2% (one stop-bit worth of drift per character). Standard crystal-based UARTs at ±50 ppm have no problem at 115200 baud over 1 m of wire; RC-oscillator ones (like internal AVR RC at ±10%) often fail at anything above 9600 baud. Everything runs client-side; no values leave your browser.