Case 1
- First frequency
- 440Hz
- Second frequency
- 444Hz
4.00Hz
Open with these valuesBeat Frequency Calculator
4.00Hz
Result: 4.00 HzTwo tones sounded together swell and fade at the difference of their frequencies. A string at 444 Hz against a fork at 440 Hz gives four beats per second. Which frequency you enter first makes no difference, and identical tones give zero beats — that is how a string gets tuned.
The numbers at a glance
Held fixed: First frequency 440.00 Hz.
| Second frequency (Hz) | Result (Hz) |
|---|---|
| 0.00 | 440.00 |
| 200.00 | 240.00 |
| 400.00 | 40.00 |
| 444.00Your value | 4.00 |
| 600.00 | 160.00 |
| 800.00 | 360.00 |
Worked examples
Case 2
- First frequency
- 256Hz
- Second frequency
- 260Hz
4.00Hz
Open with these valuesCase 3
- First frequency
- 1000Hz
- Second frequency
- 997Hz
3.00Hz
Open with these valuesHow it's calculated
f_beat = |f₁ − f₂|
- StepEnter the first frequency in hertz.
- StepEnter the second, in the same unit.
- ResultRead the beats per second; zero means the two match.
Reference table
| Two frequencies (Hz) | Situation | Beats per second |
|---|---|---|
| 440, 444 | String sharp against a tuning fork | 4 |
| 256, 260 | Middle C against a slightly sharp one | 4 |
| 100, 100 | Perfectly in tune | 0 |
| 1000, 997 | A tone flat by three hertz | 3 |
| 60, 50.5 | Too far apart to hear as beating | 9.5 |
Questions
What is a beat frequency?
When two tones of slightly different pitch sound together, they alternately reinforce and cancel each other. The loudness swells and fades at a rate equal to the difference of the two frequencies.
Does the order of the two frequencies matter?
No. The result is the absolute difference, so 440 and 444 give the same four beats as 444 and 440.
How is this used for tuning?
Sound the string against a reference and slow the beats down. When they disappear the two frequencies are equal, and the ear notices a missing beat far more reliably than a small pitch difference.
Can you always hear the beating?
Only up to roughly 20 beats per second. Above that the swelling turns into roughness and then into two separate tones, which is perception rather than arithmetic.
Sources and last check
Information, not professional advice.