Decibel Calculator
Enter a sound pressure level (dB SPL) or a power/voltage ratio to see the ratio behind the number and compare it to everyday noise
Get a feel for what the decibel — a logarithmic unit — is actually measuring. Convert between sound pressure level (dB SPL) and signal power or voltage ratios, and compare your figure against a chart of familiar real-world noise levels.
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How to use
- Choose what you're calculating: enter a sound pressure level in dB SPL, or enter a signal power/voltage ratio.
- Type in the decibel figure or the ratio to see the corresponding relative energy in real time.
- Compare your result against the reference cards for standard noise levels — rustling leaves, normal conversation, a rock concert, a jet taking off.
FAQ
- If a sound goes up by 10 dB, how much louder is it?
- In terms of sound power, a 10 dB increase means exactly 10 times the physical energy. But because of how human hearing works, a 10 dB jump is perceived as roughly twice as loud. Add 20 dB and the energy is 100 times greater.
- If I combine two equally loud sound sources, does the decibel level double (e.g., 60dB + 60dB = 120dB)?
- No. Decibels are a logarithmic scale, so you can't just add them directly. Combining two sources of equal loudness doubles the sound energy, which only adds about 3dB to the original level — so two 60dB sources running together land around 63dB, not the 120dB you'd get from simple arithmetic addition.
- If I combine two equally loud sound sources, does the decibel level double (e.g., 60dB + 60dB = 120dB)?
- No. Decibels are a logarithmic scale, so you can't just add them directly. Combining two sources of equal loudness doubles the sound energy, which only adds about 3dB to the original level — so two 60dB sources running together land around 63dB, not the 120dB you'd get from simple arithmetic addition.