Calculate serial communication throughput and efficiency based on baud rate and frame configuration.
2026-03-28T00:00:00Z
Baud rate is the number of signal changes per second in serial communication. It's often confused with bit rate, but they're different: baud rate measures symbols per second, while bit rate measures actual data bits per second. The throughput depends on the frame structure (start bit, data bits, parity bit, stop bits).
Valid Stop Bits: Real UART hardware only supports 1, 1.5, or 2 stop bits. The calculator enforces these values. Other values will show no result.
Calculate throughput for standard serial communication: 9600 baud, 8 data bits, no parity, 1 stop bit:
Baud rate measures signal changes per second. A frame contains: start bit (1), data bits (5-9), parity bit (0-1), stop bit(s) (1-2). Only the data bits carry actual information. Overhead bits (start, parity, stop) reduce efficiency to typically 60-90%.
Common rates: 9600 (standard, reliable), 115200 (modern devices), 57600 (balance). Higher rates are faster but more susceptible to noise over long distances. For short distances (USB), 115200+ is standard. For long cables (>3m), use 9600 or less with error checking.
Real UART hardware only supports these values. 1 stop is standard (fine for modern equipment). 1.5 or 2 stop bits add delay to allow receivers to prepare for the next frame. Older/slower devices may need extra stop bits; avoid unless necessary.
Parity adds a single bit that helps detect single-bit errors during transmission. Odd parity: parity bit is set so total 1-bits is odd. Even parity: parity bit set so total 1-bits is even. Parity catches some errors but not all; use CRC for stronger error detection.
Efficiency tells you what fraction of baud rate carries actual data. A device needing 1000 characters/sec at 8 bits/char needs 8000 bps raw throughput. At 80% efficiency, you need baud rate ≥ 10000. Efficiency determines whether a given baud rate is sufficient.
Not directly, but higher baud rates are more susceptible to signal degradation over distance. RS-232/RS-485 can handle: 9600 baud at >100m, 115200 baud at ~50m. Use differential signaling (RS-485) or lower baud rates for long distances.
Baud (Bd) = signal changes per second. Bits per second (bps) = actual data rate. For NRZ (on/off encoding) in UART, they're equal, but in modem communication, multiple bits are encoded per baud, so bps > baud.
Sender and receiver must use matching parity (both odd, both even, or both none). Mismatch causes transmission errors. No parity is most common in modern protocols; use only if both devices support it. Odd/even parity adds 1 bit of overhead per frame.
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