UART Baud Error Calculator

Estimate UART baud accuracy from clock frequency and integer divider rounding.

Calculator

Inputs

UART clock (Hz) Target baud Oversampling

Results

Ideal divider—

Rounded divider—

Actual baud—

Error (%)—

Bit time error—

Assessment—

Enter UART parameters.

Notes

This calculator assumes integer divider behavior: actual baud = clock / (oversampling × divider). Some MCUs support fractional baud generators and can achieve lower error than this estimate.

FAQ

What baud error is usually acceptable?

Many systems target within ±2%, but tolerance depends on both transmitter and receiver clocks.

Why does oversampling change error?

Different oversampling factors change divider resolution, affecting rounding and final baud.