TRIR calculation: formula and worked example

The TRIR formula and the 200,000-hour base

TRIR = number of recordable cases × 200,000 ÷ total hours worked

Why 200,000? It is 100 employees × 40 hours a week × 50 weeks. Scaling every site to that base removes the effect of size, so a depot with 98,000 hours and a distribution center with 412,600 hours can be compared directly. The base is the convention of the US Occupational Safety and Health Administration (OSHA) and the Bureau of Labor Statistics (BLS), which publishes industry averages on the same scale.

Use actual hours worked by all employees, including overtime and, where your standard requires it, supervised temporary workers. Leave out vacation, sick leave and holidays, because nobody can be injured at work during hours not worked.

What counts as a recordable case

Under the OSHA recordkeeping rule, a work-related injury or illness is recordable if it results in death, days away from work, restricted work or job transfer, medical treatment beyond first aid, loss of consciousness, or a significant injury or illness diagnosed by a physician or other licensed health care professional. A plaster, an ice pack or a single check-up visit is first aid and does not count. Other countries and company standards use similar but not identical definitions, so state which one you apply when you compare rates.

Site rates and the company rate

Per site: =C2*200000/B2. North DC has 5 cases in 412,600 hours, a TRIR of 2.42. The small returns hub has only 3 cases but the highest rate, 6.12, because it worked just 98,000 hours.

For the company, add up first and divide once: =C6*200000/B6 = 13 × 200,000 ÷ 930,000 = 2.80. The simple average of the four site rates is 3.21, which is wrong: it gives the small hub the same weight as a site with four times its hours. The check in the example confirms the meaning of the base: 930,000 hours are 465 full-time equivalents at 2,000 hours each, and 13 cases per 465 FTE are 2.80 per 100 FTE.

Worked example: TRIR of a warehouse company with four sites

Hours worked and recordable cases per site are inputs (yellow). Column D calculates each site's rate and the company rate, and the rows below add the full-time equivalent check, a target case limit, the DART rate and LTIFR.

Worked example: TRIR of a warehouse company with four sites

	A	B	C	D	Formula in D
1	Site	Hours worked	Recordables	TRIR
2	North DC	412,600	5	2.42	=C2*200000/B2
3	South DC	268,400	4	2.98	=C3*200000/B3
4	Cross-dock	151,000	1	1.32	=C4*200000/B4
5	Returns hub	98,000	3	6.12	=C5*200000/B5
6	Company	930,000	13	2.80	=C6*200000/B6
7
8	Average of the site TRIRs (wrong)			3.21	=AVERAGE(D2:D5)
9	Full-time equivalents (2,000 h each)			465.0	=B6/2000
10	Recordables per 100 FTE			2.80	=C6/D9*100
11
12	Target TRIR next year			2.00
13	Max recordables at target (same hours)			9	=ROUNDDOWN(D12*B6/200000,0)
14
15	DART cases (days away, restricted, transfer)			8
16	DART rate			1.72	=D15*200000/B6
17	Lost-time cases			5
18	LTIFR (per 1,000,000 hours)			5.38	=D17*1000000/B6

Fictional company and illustrative numbers. Formulas follow the OSHA 200,000-hour and the 1,000,000-hour conventions in general terms. Educational only, no affiliation with OSHA, BLS or the ILO, and not legal or compliance advice.

From a TRIR target to a case limit

A target works backwards: allowed cases = target TRIR × hours ÷ 200,000. At 930,000 hours, a target of 2.0 allows 9.3 cases. Cases are whole numbers and 10 would exceed the target, so round down with =ROUNDDOWN(D12*B6/200000,0): 9 cases, four fewer than this year. If hours grow, the limit grows with them.

DART rate and LTIFR

TRIR counts every recordable case. Two related rates focus on the more serious ones:

• DART rate: cases with days away, restricted work or job transfer, on the same 200,000-hour base. 8 DART cases give 8 × 200,000 ÷ 930,000 = 1.72.
• LTIFR (lost time injury frequency rate): lost-time injuries per 1,000,000 hours, the base common in the UK, Australia, the EU and in ILO statistics. 5 lost-time cases give 5.38. The same cases on the 200,000 base would be 1.08, so always check the base before comparing figures.

Is my TRIR good?

Compare with the average for your industry, not with an all-industry figure. In recent BLS surveys the US private-industry rate has been roughly between 2.4 and 2.8 cases per 100 full-time workers, while warehousing, construction and manufacturing usually run higher than office-based industries. Check the latest BLS release for your sector code. Small sites swing a lot from year to year because one case moves the rate by several points, so look at a rolling 12-month rate as well. To flag sites above their benchmark automatically, a formula rule works well, see conditional formatting formula examples.

Common mistakes

• Averaging the site rates. The company TRIR is total cases × 200,000 ÷ total hours. A simple average overweights small sites.
• Using paid hours instead of hours worked. Vacation, sick leave and holidays are not exposure hours and make the rate look better than it is.
• Counting first-aid cases. Only cases that meet the recordable criteria belong in TRIR. Track first aid and near misses separately as leading indicators.
• Mixing the 200,000 and 1,000,000 bases. An LTIFR of 5.38 and a lost-time rate of 1.08 describe the same cases. Convert before comparing.
• Rounding a case limit up. Allowed cases at a target are a maximum, so round down.
• Judging a small site on one year. With under 100,000 hours, a single case adds about 2 points. Use rolling rates and several years.