Noise Dose Calculator
One saw cut does not make a hearing case. A whole shift of saws, nailers and a compressor might. This adds the periods together the way 1926.52(d)(2) says to, and shows whether the day crosses the line where a hearing protection and conservation program become mandatory.
Pre-filled with example readings for one carpenter’s 8-hour shift. Enter each period at a roughly steady level, in dBA (slow response), and its hours.
113%
Construction exposure factor Fe (1.13; over 1.00 exceeds)
136%
Dose counting every period at 80 dBA and above
92.2
8-hour TWA, dBA
Exceeds the construction limit. 1926.52 requires feasible engineering or administrative controls, hearing protection, and a continuing, effective hearing conservation program.
The arithmetic, shown
T = 8 ÷ 2^((L − 90) ÷ 5) hours
1. 100 dBA for 1 h → T = 2.00 h → C/T = 0.500
2. 95 dBA for 2.5 h → T = 4.00 h → C/T = 0.625
3. 88 dBA for 2.5 h → T = 10.56 h → C/T = 0.237 (dose only)
4. 78 dBA for 2 h → T = 42.22 h → C/T = 0.047 (below 80, not counted)
Fe = Σ C/T for periods ≥ 90 dBA = 1.125
TWA = 16.61 × log₁₀(D ÷ 100) + 90 = 92.2
What a noise dose is
OSHA does not limit a sound level; it limits a sound level for a length of time. The construction table allows 8 hours at 90 dBA, and every 5 dB louder halves the time — OSHA calls this the 5 dBA exchange rate. Mix several levels in one day and you add each period as a fraction of its allowed time. The rule says so in plain words: when exposure is made up of periods at different levels, “their combined effect should be considered, rather than the individual effect of each.”
| Duration per day, hours | Sound level, dBA slow response |
|---|---|
| 8 | 90 |
| 6 | 92 |
| 4 | 95 |
| 3 | 97 |
| 2 | 100 |
| 1½ | 102 |
| 1 | 105 |
| ½ | 110 |
| ¼ or less | 115 |
Table D-2, Permissible Noise Exposures, read from 29 CFR 1926.52 on 2026-10-18.
How to use the calculator
- Split the shift into steady periods. Saw time, nailing time, background time. Fluctuations at intervals of a second or less count as continuous noise under 1926.52(c), so a nailer firing every second is one period, not hundreds.
- Enter a measured level for each. A sound level meter on the A-scale, slow response, at the worker’s ear — or a dosimeter, which does this sum for you over the whole shift.
- Read Fe first. It is the construction test. Over 1.00 (100%) and the exposure exceeds the table.
- Then read the dose and TWA. They count quieter periods too, down to 80 dBA, the way general industry computes the 85 dBA action level. Construction has no such action level, but it is the early warning.
OSHA’s own worked example
The standard prints a sample computation. A worker exposed to 110 dBA for ¼ hour, 100 dBA for ½ hour and 90 dBA for 1½ hours scores 0.500 + 0.25 + 0.188 = 0.938. Below 1, so within the limit — even though the 110 dBA quarter-hour alone used half the day’s allowance. Enter those three rows above and you will get the same 0.94.
Caution
What the rule requires once you are over
Three duties, in this order. Feasible administrative or engineering controls first — quieter tools, enclosing the compressor, moving the cut station, rotating the cutter. If they fail, hearing protection under 1926.101, where inserted plugs must be fitted or determined individually by a competent person and plain cotton is not acceptable. And in all cases above the table, “a continuing, effective hearing conservation program shall be administered.” Plan the controls on the JHA for the task, and log who was trained on the training matrix.
The construction rule does not spell out what that program contains. The general-industry rule, 1910.95(c) through (o), does — monitoring, audiometric testing, hearing protectors, training and records — and it starts at an 85 dBA TWA or a 50% dose rather than at 90. OSHA’s construction page also points to a consensus standard, ANSI/ASSP A10.46-2020, which applies to construction and demolition workers at 85 dBA and above. It is not an OSHA rule, but it is the obvious template.
Warning
The rule text
Quoted from the current eCFR text of title 29, read on 2026-10-18.
When employees are subjected to sound levels exceeding those listed in Table D-2 of this section, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of the table, personal protective equipment as required in subpart E, shall be provided and used to reduce sound levels within the levels of the table.
In all cases where the sound levels exceed the values shown herein, a continuing, effective hearing conservation program shall be administered.
If the value of F e exceeds unity (1) the exposure exceeds permissible levels.
(b) Ear protective devices inserted in the ear shall be fitted or determined individually by competent persons. (c) Plain cotton is not an acceptable protective device.
The employer shall administer a continuing, effective hearing conservation program, as described in paragraphs (c) through (o) of this section, whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.
Sources, with the date each was read
- 29 CFR 1926.52 — Occupational noise exposure (eCFR)read 2026-10-18
- 29 CFR 1926.101 — Hearing protection (eCFR)read 2026-10-18
- 29 CFR 1910.95 and Appendix A — Occupational noise exposure, general industry (eCFR)read 2026-10-18
- Occupational Noise Exposure — overview (OSHA)read 2026-10-18
- Noise in Construction (OSHA)read 2026-10-18