Arduino Serial Baud/Timing Calculator

About this tool

Work out how long it actually takes to send data over Serial at a given baud rate and frame format — useful for sizing timeouts, estimating how long a sensor data dump or firmware-over-serial transfer will take, or sanity-checking whether a baud rate can keep up with your data rate.

Frequently asked questions

What does "8N1" mean?

8 data bits, No parity bit, 1 stop bit — the default and by far the most common serial frame format, including Arduino's default Serial.begin(baud) (equivalent to Serial.begin(baud, SERIAL_8N1)).

Why is effective throughput lower than the baud rate?

Baud rate counts every bit on the wire, including the start bit, any parity bit, and stop bit(s) — none of which carry actual data. With 8N1, each byte takes 10 bit-times to send 8 bits of data, so effective throughput is baud ÷ 10 × 8, about 80% of the raw baud rate.

Why is 74880 baud in the list?

It's the baud rate ESP8266 modules use for their boot-time diagnostic output — an oddly specific value that trips people up when their serial monitor shows garbage at the usual 115200.