Short answer: dB (decibels) measure how loud a sound is; Hz (hertz) measure how high or low it is. They describe two different properties of the same sound, so you can’t convert Hz to dB or dB to Hz. A 100 Hz hum and a 5,000 Hz whistle can both be 70 dB.
Every sound has both a level and a frequency. Think of a piano: pressing a key harder makes the note louder (more dB), while moving to a key further right makes it higher (more Hz). This guide explains both units side by side, shows what you can calculate with them together, and how to measure each one with free online tools.
dB vs Hz at a Glance
| Decibel (dB) | Hertz (Hz) | |
|---|---|---|
| Measures | Sound level: how strong the pressure change is | Frequency: how many vibrations per second |
| You hear it as | Loudness | Pitch (low or high) |
| Human range | About 0 dB (threshold) to 130 dB (pain) | About 20 Hz to 20,000 Hz |
| Scale | Logarithmic: +10 dB ≈ twice as loud | Linear count, but pitch is heard logarithmically (an octave doubles the Hz) |
| Everyday example | Conversation 60 dB, lawn mower 90 dB | Mains hum 50/60 Hz, middle A 440 Hz |
| Measured with | Sound level meter or decibel meter | Frequency analyzer or tuner |
| Named after | Alexander Graham Bell (a tenth of a bel) | Heinrich Hertz, who proved radio waves exist |
Can You Convert Hz to dB (or dB to Hz)?
No. Hz and dB measure different things, like kilometres and kilograms. There is no formula that turns a frequency into a level, and a “Hz to dB converter” doesn’t exist. The same frequency can be any loudness, and the same loudness can be any frequency.
What people usually need when they search “hz to db” is one of these, all of which combine the two units:
- A level at a frequency: how many dB a sound has at 100 Hz, at 1 kHz and so on. That is a spectrum, which the frequency analyzer shows live from your microphone.
- Frequency response: a speaker or microphone spec such as “40 Hz – 20 kHz ±3 dB” means the level stays within 3 dB across that range.
- Filter slopes in dB per octave: a first-order filter falls by 6 dB each time the frequency doubles (20 dB per decade); a fourth-order crossover falls 24 dB per octave.
- dB-Hz: a real unit in radio and GPS, meaning decibels relative to 1 Hz of bandwidth. A 1 MHz bandwidth is 60 dB-Hz, and GPS receivers report signal strength (C/N₀) as roughly 35–50 dB-Hz.
- Weighting: dB(A) and dB(C) adjust the level at each frequency to match hearing; see dBA vs dBC.
What Is a Decibel (dB)?
A decibel expresses a ratio on a logarithmic scale. For sound in air, the reference is 20 µPa (see sound pressure level), so 0 dB SPL is roughly the quietest sound a healthy young ear can hear, 60 dB is conversation and 120 dB is painful. Because the scale is logarithmic, 70 dB isn’t slightly more than 60 dB: it has 10 times the sound energy and sounds about twice as loud (hear the steps with the volume level comparator). The decibel chart places everyday sounds on the scale. Read what a decibel is and why the decibel scale is logarithmic for the details.
What Is Hertz (Hz)?
One hertz is one cycle per second. A sound at 440 Hz makes the air vibrate 440 times a second, which we hear as the A above middle C. Doubling the frequency raises the pitch by one octave. Some reference points:
| Frequency | What it sounds like |
|---|---|
| 20–60 Hz | Deep sub-bass you feel as much as hear; wind turbines and large engines |
| 50 or 60 Hz | Electrical mains hum (50 Hz in Europe and most of Asia, 60 Hz in North America) |
| 85–255 Hz | Fundamental of adult speaking voices (lower for men, higher for women) |
| 440 Hz | Tuning note A4 |
| 2,000–5,000 Hz | The range your ears are most sensitive to; consonants, alarms, a baby’s cry |
| 8,000–20,000 Hz | Sizzle of cymbals and “s” sounds; the upper limit falls with age |
Each frequency also has a wavelength: at 343 m/s, a 20 Hz wave is about 17 m long and a 20,000 Hz wave about 1.7 cm. Work it out for any frequency with the audio wavelength calculator, or listen to any pitch with the tone generator.
How Frequency Changes How Loud dB Sounds
Although you can’t convert one into the other, frequency does change how loud a given number of decibels seems. Your ears are most sensitive between about 2,000 and 5,000 Hz and much less sensitive to deep bass. The equal-loudness contours of ISO 226 show that at quiet levels a 100 Hz tone needs roughly 20 dB more than a 1,000 Hz tone to sound equally loud. That is why sound level meters apply A-weighting, which turns down low frequencies the way the ear does; see dB vs dBA.
Which One Damages Hearing: dB or Hz?
Hearing damage depends mainly on the level in dB and how long you are exposed: long daily exposure above 85 dB(A) is the recognised risk (see is 85 dB dangerous?). Frequency plays a part too. The ear canal boosts sound between about 2,000 and 4,000 Hz, so noise-induced hearing loss usually appears first as a dip around 4,000 Hz. A high frequency on its own isn’t harmful at a low level: a quiet 15,000 Hz tone is harmless, while a loud 500 Hz tone can damage hearing.
How to Measure dB and Hz
- Level (dB): use the free sound decibel meter on our homepage, ideally after you calibrate your microphone.
- Frequency (Hz): use the frequency analyzer to see which frequencies a sound contains and the loudest peaks.
- Both over time: to find what is causing a hum, the background noise test reports the level and detects 50/60 Hz mains hum.
- Your hearing across frequencies: the online hearing test checks each ear from 250 to 8,000 Hz.
Frequently Asked Questions
Is Hz louder than dB?
Neither is “louder”: Hz is pitch and dB is level. A higher number of Hz means a higher pitch, not a louder sound.
How many Hz is 85 dB?
85 dB can be at any frequency. The number of decibels says nothing about the pitch; you need a frequency analyzer to find the Hz.
Can a sound have a high Hz and a low dB?
Yes. A faint 12,000 Hz test tone is high-pitched but very quiet, while a truck’s rumble is low-pitched and loud.
Why do speaker specs list both Hz and dB?
Frequency response (Hz range ±dB) tells you which pitches the speaker plays evenly, and sensitivity (dB SPL at 1 W and 1 m) tells you how loud it plays. You can convert sound pressure to dB SPL and back with the SPL converter.
What does dB/Hz mean?
It is a spectral density: the level in each 1 Hz slice of bandwidth, used for noise spectra. dB-Hz (with a hyphen) is the related unit for bandwidth or carrier-to-noise density in radio and GPS. The decibel units guide lists every dB unit.