Two-Tone Beat Frequency Calculator
How fast will two nearby steady tones beat, and how many cycles can you observe?
Method, formula and assumptions
Beat frequency is the absolute frequency difference. Beat period is its reciprocal; observed cycles equal difference x duration. The mean is the midpoint between the two tone frequencies.
Input definitions and supported units
- First tone (Hz): Measured or assumed numerical value, from 1 to 100000; must be positive.
- Second tone (Hz): Measured or assumed numerical value, from 1 to 100000; must be positive.
- Observation duration (seconds): Measured or assumed numerical value, from 0 to 1000000; zero is supported where the stated method permits it.
Worked example with answer
440 and 442 Hz differ by 2 Hz, giving a 0.5-second beat period. Ten seconds contains 20 beat cycles; the mean tone is 441 Hz.
How to use the results
A slower beat pattern indicates closer frequencies in this ideal two-tone model. Equal frequencies are rejected because a finite beat period is undefined.
Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.
Limitations and references
Beating requires sufficiently similar tones and listening conditions; this does not predict perceived roughness or musical consonance for arbitrary complex sounds.
The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.
Related planning tools
Creator & reviewers
Creator persona
- Casey RowanUnits, conversions & measurement
Reviewer personas
- Devon ShawFormula & assumptions review
- Sage MitchellClarity & usability review