UART Baud Rate Error Calculator
Calculate rounded UART divider, actual baud and relative mismatch against an independently entered peer baud.
YOUR CALCULATION
Result
—
Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use a positive whole counter divisor and compare the resulting local baud with the actual peer rate.
Divisor=max(1,round(clock/(oversampling×target))); baud=clock/(oversampling×divisor)
Worked example
16 MHz with 16× oversampling and nominal 115200 baud rounds to divisor 9 and actual baud 111111.111, an error of −3.54938272%.
Assumptions and input details
Register value may be divisor−1 on some devices; this tool reports the physical divisor. End-sample drift is a magnitude-only accumulated bit-period estimate. Start synchronization, sample voting, frame formats and permissible link error are device-specific and not inferred.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Find the nearest valid integer divider for a target clock, showing actual rate and signed error.
Convert frame counts, elapsed seconds and timecode, or measure a start/end timecode span. Select exact fractional rates and an explicit drop-frame convention.
Estimate first and final packet arrival over equal-rate store-and-forward links, including packet overhead and per-hop propagation.
Reserved advertising space.