Compare two measured sound levels
Full chart ↓Conversation: 60–70 dBA; motorcycles: 80–110 dBA; sirens: 110–129 dBA. A 10 dB increase means 10× the sound-energy quantity under comparable conditions. NIH/NIDCD examples vary with distance and equipment; the chart below preserves each source’s dB or dBA label.
Example: Comparing 90 dBA with 70 dBA gives a 20 dB increase: 100 times the A-weighted mean-square pressure and 10 times the A-weighted RMS sound pressure. At 90 dBA, the NIOSH constant-level dose formula gives approximately 151 minutes for a 100% daily dose.
Compare A-weighted levels measured on the same basis; this tool does not measure sound.
On this page
Decibel chart of common sounds: 0–160 dB
These are approximate published examples, not measurements of your device or location. The unit column preserves the source’s label: dBA is A-weighted; a general dB label does not specify a weighting. Compare ranges and context, then measure the real exposure when it matters.
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| Threshold-of-hearing reference | 0 | 0 | dBA | OSHA illustration at 1,000 Hz; not absolute silence |
|---|---|---|---|---|
| Quiet study room | 20 | 20 | dBA | OSHA illustrative setting; actual room conditions vary |
| Whisper | 30 | 30 | dB | Quiet, close conversation; illustrative level |
| Refrigerator hum | 40 | 40 | dB | Household appliance; varies by model and distance |
| Dishwasher | 45 | 65 | dB | Household appliance; full published range |
| Urban residence | 50 | 50 | dBA | OSHA illustrative setting; actual local conditions vary |
| Normal conversation | 60 | 70 | dBA | Ordinary speech; measurement distance matters |
| Movie theater | 74 | 104 | dBA | Soundtrack level, seat and cinema vary |
| Lawn mower | 80 | 100 | dB | Near operating equipment; protect hearing |
| Motorcycle / dirt bike | 80 | 110 | dBA | Engine, speed and exposure location vary |
| Freight train | 80 | 80 | dBA | OSHA example at 100 ft (about 30 m) from the source |
| Some power tools | 85 | 90 | dBA | NIOSH example band; individual tools can exceed it |
| Sporting event | 94 | 110 | dBA | Crowd and amplified sound; location varies |
| Headphones at maximum volume | 94 | 110 | dBA | Device-dependent; reduce playback volume |
| Rock concert / nightclub | 95 | 115 | dB | Near amplified music; distance from speakers matters |
| Emergency siren | 110 | 129 | dBA | Near the source; move away when possible |
| Jet takeoff | 130 | 130 | dBA | OSHA example at 200 ft (about 61 m) from the source |
| Fireworks / firecracker | 140 | 160 | dBA | Impulsive sound; continuous-dose formula does not apply |
Example ranges: NIH/NIDCD noise-induced hearing loss, NIH/NIDCD Listen Up chart, NIOSH workplace examples, and the OSHA decibel-scale illustration. Fireworks are impulsive: do not apply continuous-exposure times to this row.
Decibel Chart — all 18 reference rows. Read the stated conditions and sources.
NIOSH exposure time chart: 85–115 dBA
NIOSH’s occupational recommended exposure limit is 85 dBA averaged over 8 hours, with a 3 dB exchange rate. Each 3 dB increase halves the time corresponding to the same dose. The table assumes one constant level and no other contributing noise exposure. It is a risk-management reference, not a promise that hearing damage cannot occur. NIOSH recommendation.
| Constant level (dBA) | Time corresponding to 100% daily dose |
|---|---|
| 85 | 8 hours |
| 88 | 4 hours |
| 91 | 2 hours |
| 94 | 1 hour |
| 97 | 30 minutes |
| 100 | 15 minutes |
| 103 | 7.5 minutes |
| 106 | 3.75 minutes |
| 109 | 1.875 minutes |
| 112 | 56.2 seconds |
| 115 | 28.1 seconds |
T = 8 × 2(85 − L)/3 hours, where L is a constant A-weighted level. Multiple exposures share the same daily dose: add each duration divided by its corresponding T. For example, 4 hours at 85 dBA uses 50% and 1 hour at 91 dBA uses another 50%.
Do not use this table to time exposure to fireworks, firearms or other impulsive sounds. Their peak level and impulse character need separate assessment.
Why a few decibels make a large difference
Decibels express a ratio on a logarithmic scale. For levels using the same reference and weighting, the mean-square-pressure ratio is 10ΔL/10 and the RMS-pressure ratio is 10ΔL/20. With comparable propagation conditions, the energy interpretation follows the mean-square-pressure ratio.
| Level increase | Mean-square-pressure ratio | RMS-pressure ratio |
|---|---|---|
| +3 dB | 2.00× (approximately) | 1.41× |
| +6 dB | 3.98× | 2.00× (approximately) |
| +10 dB | 10× | 3.16× |
| +20 dB | 100× | 10× |
| +30 dB | 1,000× | 31.62× |
Thus, 90 dB versus 70 dB is a 20 dB change, not a 29% sound-energy increase. The physical ratio is 100 to 1. Perceived loudness also depends on frequency, duration and the listener, so it cannot be read directly from an energy ratio. OSHA technical explanation of the decibel scale.
Adding two sound sources: 60 dB + 60 dB ≈ 63 dB
Independent, uncorrelated sources combine through energy, not ordinary addition of their decibel labels:
Ltotal = 10 log10(10L₁/10 + 10L₂/10).
Two independent 60 dB sources produce approximately 63.01 dB together at the measurement point, provided each source alone produces 60 dB there. A 70 dB source added to a 60 dB source gives about 70.41 dB: the louder source dominates.
This calculation does not describe two perfectly phase-related tones in every location. Interference and room acoustics can change the local result. Use measurements or an appropriate acoustic model for an actual installation. OSHA noise measurement principles.
dB, dBA, sound pressure and sound power
dB is a logarithmic unit and needs a quantity and reference. For sound pressure in air, the usual reference is 20 micropascals. dBA identifies A-frequency weighting, commonly used for occupational noise assessment. A weighting adjusts the contribution of different frequencies; it is not a distance correction.
A product’s sound power rating and a sound pressure measurement at the listener are different quantities. Sound pressure changes with location and surroundings. Do not compare a sound-power specification with an at-ear sound-pressure value as if they were the same measurement.
Also distinguish a momentary reading, a peak reading and an average over time. A low average can conceal a short intense event. The units, weighting, time basis and measurement position should travel with the number. NIOSH: sound level, TWA and dose.
How to make a useful noise comparison
- Use the same quantity. Compare sound pressure with sound pressure, not with sound power.
- Match the weighting and averaging. Record whether the reading is dBA and whether it is a steady, average or peak value.
- Record distance and position. A measurement beside a tool is different from one across the room.
- Capture real operating conditions. Speed, loading and the background environment can change the level.
- Measure exposure over time. For moving workers or changing tasks, a personal dosimeter is more informative than one spot reading.
A sound-level meter measures sound at a location; a dosimeter tracks a person’s exposure. A phone app may help identify a noisy area, but the phone, microphone, calibration and measurement range limit its use. NIOSH notes that apps may not meet regulatory measurement requirements. NIOSH measurement guidance.
NIOSH recommendations and OSHA requirements differ
The occupational reference in this page uses NIOSH: 85 dBA for 8 hours and a 3 dB exchange rate. OSHA’s general-industry permissible-exposure framework uses 90 dBA for 8 hours and a 5 dB exchange rate, with a separate 85 dBA action level for a hearing-conservation program.
These are different systems with different purposes. Do not substitute this NIOSH table for an OSHA compliance calculation, or treat an occupational limit as a universal residential-noise or recreational-listening standard. Applicable requirements depend on the work and jurisdiction. OSHA occupational-noise overview.
The practical response to a high measured level is to reduce the source, reduce exposure and use properly selected protection as appropriate. A table is useful for recognizing the scale of the problem; it does not replace a workplace noise assessment.
Decibel Chart FAQs
How loud is 70 decibels?
NIH/NIDCD places normal conversation at roughly 60–70 dBA. A 70 dBA measurement is a useful conversational-scale reference, but it does not identify the source, distance or sound quality by itself.
Is 85 dBA safe for 8 hours?
85 dBA for 8 hours is the NIOSH occupational recommended exposure limit. It is not a guarantee of no hearing injury for every person. Repeated exposure, individual susceptibility and other noise during the day matter.
Is 100 dB twice as loud as 50 dB?
No. A 50 dB increase corresponds to 100,000 times the mean-square sound pressure under comparable measurement conditions. Perceived loudness is a separate response and does not scale directly with that ratio.
How long is the NIOSH exposure reference at 100 dBA?
15 minutes corresponds to 100% of the daily occupational dose in the 85 dBA / 8-hour / 3 dB model, assuming no other noise exposure. It is not permission to remain in hazardous noise and does not apply to impulse sounds.
Does doubling the distance always reduce sound by 6 dB?
Approximately 6 dB per doubling is a free-field point-source relationship under appropriate conditions. Reflections, multiple sources, barriers, source geometry and background sound can change the result. Do not apply it as a universal indoor rule.
Can I add two decibel readings together?
Use logarithmic addition for independent sources measured on the same basis. Two equal 60 dB sources give about 63 dB together, not 120 dB. Phase-related tones require more care because interference can change the local pressure.
Does zero decibels mean there is no sound?
No. For sound pressure in air, 0 dB SPL corresponds to the reference pressure of 20 micropascals. It is a reference level near the hearing threshold at some frequencies, not an absence of pressure variation. Negative dB SPL values are possible; this comparison tool accepts 0–160 dBA.
Sources and Data Basis
Reference basis reviewed October 25, 2026. Follow the scope and conditions given with each table and lookup result.
- NIH/NIDCD — Noise-Induced Hearing LossCommon sound ranges: conversation 60–70dBA, movies74–104dBA, motorcycles80–110dBA, music/sport/concert94–110dBA, sirens110–129dBA, fireworks140–160dBA. Variation with distance/duration and impulse hazards.
- NIH/NIDCD — Listen Up sound-level chartApproximate contextual sounds: whisper30dB, refrigerator40dB, dishwasher45–65dB, mower80–100dB, concerts95–115dB. Published chart labels dB; do not imply a calibrated dBA measurement for every example.
- CDC/NIOSH — Noise-Induced Hearing Loss85dBA for8h REL; every3dB increase halves exposure duration; susceptibility varies, not a guaranteed safe time.
- CDC/NIOSH — Understand Noise ExposureA-weighting, 3dB exchange rate, dose and TWA measurement; SLM versus personal dosimeter.
- OSHA Technical Manual — NoiseLogarithmic sound-pressure formulas, sound-level addition, frequency weighting, OSHA versus NIOSH distinction.
- OSHA — Occupational Noise ExposureGeneral industry PEL90dBA8h/5dB exchange; hearing conservation action level85dBA8h; NIOSH3dB recommendation distinct.