A safety coordinator who reports TRIR more than once a year usually ends up with a spreadsheet for it: recordable cases times 200,000, divided by hours worked. That formula is correct the day it's built. It fails quietly later -- a DART formula copied from the TRIR cell without changing its range, or an hours-worked total nobody updated this quarter -- and neither failure looks wrong from the output alone.
A spreadsheet can compute TRIR and DART rate correctly, and most EHS teams already have one. What it does not do on its own is flag a copied formula pointing at the wrong case range, remind anyone to refresh the hours-worked total for the current period, or solve the reverse question of how many more injury-free hours close the gap to a target.
This calculator applies OSHA's own 200,000-hour formula (29 CFR 1904) fresh from the counts you enter every time, keeps TRIR and DART rate as two independently computed figures rather than one formula copied into a second cell, and adds the injury-free-hours-to-target figure -- the rearranged algebra a one-line spreadsheet formula stops short of.
| Question | Where to answer it |
|---|---|
| Can I compute TRIR and DART rate in a spreadsheet? | Yes -- if the formula is right and stays right as periods and case counts change. |
| Would I notice a DART formula silently pointing at the TRIR case range? | Not from the output alone -- both cells would still show a plausible-looking rate. |
| Does either one remind me to refresh the hours-worked total for this period? | Neither. Both trust whatever number is entered as this period's total hours. |
| Does either one tell me how many more injury-free hours reach a target rate? | This calculator solves it directly. A spreadsheet only does if someone has already rearranged the formula for it. |
| Is anything I enter uploaded anywhere? | No. The calculator runs entirely in your browser; nothing is sent to a server. |
Yes -- the formula itself is one line: recordable cases times 200,000, divided by total hours worked. DART rate is the same formula against a different case count. Both are easy to get right once and easy to get wrong quietly later, which is where a hand-built sheet most often fails, not in the arithmetic itself.
The DART formula gets built by copying the TRIR formula and changing the multiplier reference, but not the case-count range -- so it silently reports the same number as TRIR, or a stale one, instead of the DART-only subset. A safety coordinator scanning the two output cells has no way to tell from the numbers alone that one of them is pointing at the wrong range.
Because total hours worked is the denominator, and it is the one cell in the sheet with no natural trigger to update it. A recordable case gets entered the day it happens; hours worked for the quarter usually gets typed in once and left there. A rate computed against last quarter's hours total looks like a normal number -- it is just the wrong one.
Only if someone rearranges the formula for it, which almost none do. Solving for the hours that dilute a fixed case count down to a target rate means isolating hours worked on the other side of the TRIR equation -- an algebra step past the one-line formula most sheets stop at. Most safety coordinators who want that number instead guess at a timeline or wait for the annual OSHA 300A summary to see where the year landed.
No. The calculator this page links to runs entirely in your browser; nothing you enter -- case counts, hours worked, or your company -- is uploaded or stored anywhere but this device.