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    Severity Rate

    Definition

    A measure relating days lost, or another defined severity measure, to hours worked. Formulas and day-count rules differ between reporting schemes.

    Editorial definition: The QHSE Standard, updated 3 October 2026 · https://qhsetech.com/glossary/severity-rate

    Scope: State the numerator, multiplier, population and period. Different reporting schemes use different formulas.

    Sources checked: . Examples are editorial illustrations.

    What the US recording rules and BLS pages say about counting days

    The term severity rate is used for measures of how serious cases were, usually built from days lost, where an incidence rate describes how many there were. The pages opened for this term do not define a severity rate. The Bureau of Labor Statistics page on computing rates gives one formula, cases times 200,000 over the hours employees worked, and applies it to all recordable cases, to cases with days away from work and to the DART rate. It explains the 200,000 as the hours of 100 full-time employees across a year, at 40 hours for 50 weeks. The page does not mention a severity rate, days lost per case or any other severity measure.

    What the pages do give is the day-count rule. Under OSHA's 1904.7, counting days away from work starts on the day after the injury, not on the day it occurred. All calendar days count, including weekends and holidays and days the employee was not scheduled to work. The employer may cap the total at 180 calendar days, and entering 180 is treated as adequate. Restricted work and job transfer days are counted the same way. The cap matters when one long case would otherwise dominate a total, as the example below shows. A severity figure built on the log therefore depends on these choices, and a figure built on uncapped days or on workdays will not match one built on the rule.

    BLS reports severity in another way. Its latest-numbers page, with a release date of 22 January 2026 and reference year 2024, gives, for private industry, 888,100 cases involving days away from work and a median of 8 days away from work. A median and a mean can differ widely when a few cases are very long, and a rate per 200,000 hours is a different quantity again. Any severity rate used inside a company therefore needs its own written definition: which days, what cap, what multiplier and what population. This page is general information on US recording rules, not legal advice.

    Sources opened :

    What a severity record set looks like in software

    • For each case, the injury date, the first day counted, the days away and the days of restricted work or transfer, entered as separate fields.
    • The cap applied, such as 180 calendar days, with a flag on the cases it changed and the uncapped figure kept.
    • Hours worked by site and period, with the source of the figure and any estimate marked.
    • The written definition of each severity measure in use: numerator, multiplier, population and period.
    • Calculated measures stored with the inputs, so a figure can be reproduced: total days, mean days per case, median days and days per 200,000 hours.
    • Updates to day counts as cases close, with the date of each change.
    • Links to the investigation and the injury type, so a long case can be examined and not just counted.
    • The industry or classification used for any comparison with BLS figures, and the year of those figures.

    Severity rate, frequency rate and DART rate

    A frequency or incidence rate counts cases, and BLS applies one formula to all recordable cases and to cases with days away. A DART rate counts the cases with days away, restricted work or transfer, and it counts each case once whatever its length, so a three-day case and a 180-day case weigh the same. A severity measure counts the days, which is why it needs its own definition and why a figure from one scheme cannot be compared with another until the formulas are shown.

    A hypothetical example: five cases, three summaries

    This case is invented to illustrate the record and describes no real site. A plant has 5 cases with days away: 3, 9, 12, 40 and 200 days. The 200-day case is capped at 180, which the rule allows, so the counted days are 3 plus 9 plus 12 plus 40 plus 180, which is 244. The plant worked 400,000 hours, and its own definition is days multiplied by 200,000 and divided by hours, so the severity rate is 244 times 200,000 divided by 400,000, which is 122 days per 200,000 hours.

    The mean is 244 divided by 5, or 48.8 days per case, while the median of the five counted values, 3, 9, 12, 40 and 180, is 12 days. The record shows all three figures and notes that the mean is pulled up by one long case. At 800,000 hours the same 244 days would give 61 days per 200,000 hours, so the hours worked are an input on which the figure depends, and an estimate of them changes it. It also keeps the uncapped total of 264 days, and it states that the 122 figure follows the plant's own definition and is not a figure defined by OSHA or BLS.

    Common misunderstandings about severity rates

    • There is no single severity rate. The pages opened do not define one, so each use has to state its formula.
    • A low incidence rate does not mean low severity. A site can have few cases and several very long ones.
    • The day of injury does not count. Under 1904.7 counting begins the next day.
    • Days are not working days. The rule counts calendar days, weekends and holidays included.
    • An average does not describe a typical case. BLS reports a median, which differs from a mean when a few cases are long.

    How the severity rate relates to other glossary terms

    Severity builds on the log and sits beside the rates that count cases.

    • OSHA 300: the log where days away and restricted days are entered.
    • DART rate: a case-count rate for days away, restricted work or transfer.
    • EMR: an insurance factor built from claim costs, not days.
    • Lagging indicator: the class of measure that looks back at outcomes, as severity does.

    Records and evidence that usually exist for severity rates

    • The log with days away and restricted days for each case.
    • Hours worked by site and period, with their source.
    • The written definition and the calculation sheet.
    • Records of cap use and day-count updates.
    • Investigation records for the longest cases.
    • Management review notes that cite the figure.

    What a software tool needs to capture for severity rates

    • Separate fields for days away and restricted days, with start dates.
    • A configurable cap and a record of the uncapped figure.
    • Hours worked by period that feed every rate.
    • A stored formula with multiplier and population, visible on every report.
    • Mean, median and total days shown side by side.
    • A link from each long case to its investigation.

    Catalog profiles documenting incident recording and reporting

    The list comes from the incident platform rule. It does not show that a product calculates a severity rate or applies a day cap, which should be tested with the formula your organisation uses.

    Same rule for every product: tagged “Incident Management” or “Incident Reporting”, with a sourced incident reporting or management capability in its record, or one the vendor stated to us, labelled as vendor-stated. Documented and conditional capabilities qualify; check the linked scope before treating a module as included.

    Tekmon pays for a sponsored placement (above); its place in this list follows the same rule as every entry. How lists are ordered

    All 56 matching profiles are shown. Documentation review, not hands-on testing or a claim of compliance.

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    Frequently asked questions

    Is there one official severity rate formula?

    The OSHA and BLS pages opened for this page do not define one. BLS gives an incidence rate formula for cases, so a severity rate needs its own written definition.

    How does OSHA count days away from work?

    Counting starts the day after the injury, uses calendar days including weekends and holidays, and the total may be capped at 180 days.

    What does BLS report for days away from work?

    Its latest-numbers page, released on 22 January 2026 for reference year 2024, gives 888,100 cases with days away and a median of 8 days.

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