Baud Rate Calculator

Baud rate and bit rate are related but different — baud rate measures the number of signal changes per second, while bit rate measures how many bits are transferred. Enter your Bit Rate, Bits per Baud, and Clock Frequency, then select a Calculation Mode (Bit Rate to Baud Rate, Baud Rate to Bit Rate, or UART Configuration) to get your Baud Rate, Transmission Speed, and — for microcontroller work — the UBRR Register Value and Error Rate. Toggle Double Speed Mode (U2X) to see how it affects your actual baud rate and reduces timing error.

bps

Data transmission rate in bits per second

Number of bits transmitted per baud symbol

Hz

Peripheral clock frequency for microcontroller calculations

Enable double speed transmission mode for reduced error

Results

Baud Rate

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Transmission Speed

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UBRR Register Value

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Error Rate

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Actual Baud Rate

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Results Table

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Frequently Asked Questions

What is baud rate and how is it different from bit rate?

Baud rate is the number of signal units (symbols) transmitted per second, while bit rate is the number of bits transmitted per second. They are equal when each symbol represents one bit, but can differ in multi-bit encoding schemes.

How do I calculate baud rate from bit rate?

Divide the bit rate by the number of bits per baud symbol. For example, if you have 9600 bps and 1 bit per symbol, the baud rate is 9600 bauds. The formula is: Baud Rate = Bit Rate ÷ Bits per Baud.

What baud rate should I use for my project?

Common baud rates include 9600, 19200, 38400, 57600, and 115200 bps. Choose based on your application needs: higher rates for faster data transfer, lower rates for more reliable communication over longer distances or noisy environments.

What is the UBRR register value used for?

The UBRR (USART Baud Rate Register) value is used in microcontrollers like AVR to configure the hardware UART for the desired baud rate. It's calculated based on the system clock frequency and target baud rate.

How can I calculate baud rate from clock frequency?

For UART calculations, use the formula: UBRR = (Clock Frequency / (16 × Baud Rate)) - 1 for normal mode, or UBRR = (Clock Frequency / (8 × Baud Rate)) - 1 for double speed mode.

What is the baud rate of 1200 bits per second?

If using 1 bit per baud symbol, 1200 bits per second equals 1200 bauds. This is a common low-speed baud rate often used in older systems or applications requiring high reliability.

Why is there an error percentage in baud rate calculations?

Error occurs because the actual baud rate generated by hardware may not exactly match the desired rate due to clock frequency limitations and integer division in register calculations. Errors under 2% are typically acceptable.

What does double speed mode (U2X) do?

Double speed mode reduces the divisor from 16 to 8 in the baud rate calculation, allowing for higher precision and potentially lower error rates, especially at higher baud rates with given clock frequencies.