Sound Level Calculator
Combine decibels and distance loss.
Enter your values
Enter the source 1 in dB.
Enter the source 2 in dB.
Enter the source 3 in dB.
Enter the distance from source in m.
Enter the reference distance in m.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Combined level
- 79.5 dB
- Level at distance
- 61.4 dB
- Loss over distance
- 18.1 dB
- Hearing risk
- Below action level
Quick answer
Decibels add logarithmically — two equal sources give only a 3 dB increase.
L = 10 log10(Σ10^(Li/10))
At a glance
| What it does | Combine decibels and distance loss. |
|---|---|
| Category | Engineering |
| Inputs needed | Source 1, Source 2, Source 3, Distance from source, Reference distance |
| Main output | Combined level |
| Formula | L = 10 log10(Σ10^(Li/10)) |
| Cost | Free — no sign-up, no download |
How to use the Sound Level Calculator
- 1Enter each source level in decibels.
- 2Enter the distance and reference distance.
- 3Check against the 85 dB action level.
Inputs explained
- Source 1(dB)
- Enter the source 1 in dB.
- Source 2(dB)
- Enter the source 2 in dB.
- Source 3(dB)
- Enter the source 3 in dB.
- Distance from source(m)
- Enter the distance from source in m.
- Reference distance(m)
- Enter the reference distance in m.
Worked example
Using the values the calculator loads with:
Inputs
- Source 178 dB
- Source 274 dB
- Source 30 dB
- Distance from source8 m
- Reference distance1 m
Results
- Combined level79.5 dB
- Level at distance61.4 dB
- Loss over distance18.1 dB
- Hearing riskBelow action level
Frequently asked questions
Why don't decibels add normally?
The scale is logarithmic — doubling power adds only 3 dB.
How much does distance help?
Each doubling of distance drops free-field level by 6 dB.
What do I need to enter into the Sound Level Calculator?
Just 5 values: source 1, source 2, source 3, distance from source, reference distance. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Sound Level Calculator work out the answer?
Decibels add logarithmically — two equal sources give only a 3 dB increase. It applies the formula L = 10 log10(Σ10^(Li/10)) and shows the working so you can check each step by hand.
Is the Sound Level Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.