How to calculate lost workday rate on OSHA 300 log

Written by curt guillory
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How to calculate lost workday rate on OSHA 300 log
Calculating the D.A.R.T Rate on an OSHA 300 log is a simple process. (paperwork image by Pix by Marti from

Calculating lost workday rates on OSHA's 300 log is a straightforward process. While OSHA requirements are stringent, since Jan. 1, 2002, things have changed in order to make reporting less difficult and more accurate. According to OSHA's website, "OSHA's new recordkeeping log is easier to understand and to use." This is welcomed news for those responsible for keeping OSHA records. states, "The Lost Workday Rate is now referred to as the D.A.R.T (Days Away, Restricted, or Transferred) Rate."

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  1. 1

    Gather the number of lost workdays. states that for the OSHA 300 log lost work days, "cases involving days away and/or restricted work activity, and/or job transfer" should be used in the D.A.R.T. calculation.

  2. 2

    Calculate the total hours worked for all employees of your company for a calender year.

  3. 3

    Using 200,000 as the standard base number of hours worked for 100 full-time equivalent employees is also required to calculate the D.A.R.T. rate. The website explains, "Using this standardised base rate, any company can calculate their rate(s) and get a percentage per 100 employees."

  4. 4

    Calculate the D.A.R.T. rate using the formula (N divided by EH) times (200,000), where N equals the number of cases involving days away and/or restricted work activity, and/or job transfer; EH equals is the total number of hours worked by all employees during the calendar year. uses this example: Employees of an establishment, including management, temporary, and leased workers, worked 645,089 hours at the worksite. There were 22 injury and illness cases involving days away and/or

    restricted work activity and/or job transfer from the OSHA-300 Log (total of

    column H plus column I). The DART rate would be (22 divided by 645,089) times

    (200,000) = 6.8.

Tips and warnings

  • Calculating the D.A.R.T. rate will only be as accurate as your company's record keeping as it relates to missed workdays.
  • Not all businesses are required to maintain an OSHA 300 log. Check your businesses requirements at OSHA's website
  • Do not confuse the D.A.R.T. rate with the Days Away from Work Injury and Illness Case Rate. This rate does not take employee transfers into consideration.

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