Incidence Rate Calculator

The general-purpose BLS (Bureau of Labor Statistics) incidence rate formula — the same underlying calculation used for TRIR, DART, and DAFW rates, applicable to any case category on your OSHA Form 300A.

Case Category Sets the correct standardization multiplier automatically — illness-only subcategories use a different base than injury/combined categories.

Number of Cases

Total Hours Worked

0.00

INCIDENCE RATE

Formula Reference

Incidence Rate = (Number of Cases × Multiplier) ÷ Total Hours Worked

Injury / combined categories	200,000 base — rate per 100 full-time workers
Illness-only subcategories	20,000,000 base — rate per 10,000 full-time workers

Per BLS guidance, when comparing illness rates specifically by type (skin disorders, respiratory conditions, hearing loss, etc.), use the 20,000,000-hour base instead of 200,000 — this produces a rate per 10,000 equivalent full-time workers rather than per 100, since illness-specific case counts are typically much smaller and a per-100 rate would be too coarse to be meaningful.

Where to Find Your Case Counts (OSHA Form 300A)

Total Recordable	Column H + Column I + Column J
DAFW	Column H
Restricted/Transfer	Column I
Other Recordable	Column J
Illness subcategories	Columns M-1 through M-6

Based on BLS/OSHA incidence rate methodology (29 CFR 1904 and the BLS Survey of Occupational Injuries and Illnesses). This is the same general formula underlying TRIR, DART, and DAFW rate calculators — the only difference between all of them is which case category is counted in the numerator and which base (200,000 or 20,000,000) applies. Compare your result against BLS's published rates for your specific NAICS industry code and establishment size category, not a generic benchmark. For customized calculators tailored to your organization, please contact Impact Tech Solutions.