STILL / FREE TOOL
Average decibels with energy, not arithmetic.
Combine level segments with their durations. Use comparable levels with the same units, weighting and reference. This does not turn dBFS into sound pressure or decide whether an exposure is safe.
120 seconds total · arithmetic average would be 65.0 dB
Calculations stay in your browser. No microphone access or measurement upload.
The calculation
For each segment, convert the level to relative energy using 10L/10, multiply by its duration, add the contributions, divide by total time, then take 10 log10 of the result.
L = 10 log10(Σ(tᵢ × 10^(Lᵢ/10)) / Σtᵢ)
Check the assumptions
- Each input represents a constant level or an appropriate energy-average level over its segment.
- Segments describe successive periods, not simultaneous sources being added together.
- Both values use the same weighting, units, reference and compatible measurement setup.
- The result is a mathematical average, not a certified measurement or a noise-dose assessment.
Examples you can verify
60 and 60 dB for equal durations remain 60 dB. 60 and 70 dB for equal durations give approximately 67.4 dB. Increasing the duration of the louder segment moves the result toward that louder level.