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TRIR Calculator (Incident Rate, DART & LTIFR)

Calculate workplace safety rates: TRIR, DART rate and lost-time incident rate per 200,000 hours, plus LTIFR and TRIFR per 1,000,000 hours and the severity rate from days lost.

Recordable injuries and illnesses

DART cases (days away, restricted or transferred)

Lost-time injuries (days away from work)

Days lost (away from work)

Total hours worked

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How it works

TRIR = Recordable cases × 200,000 ÷ Hours worked · DART rate = DART cases × 200,000 ÷ Hours · LTIFR = Lost-time injuries × 1,000,000 ÷ Hours · Severity rate = Days lost × 200,000 ÷ Hours

Incidence rates put injury counts on a common exposure base so sites of different sizes can be compared. The US Bureau of Labor Statistics and OSHA use 200,000 hours — 100 full-time workers at 40 hours a week for 50 weeks — so a TRIR of 2.5 means 2.5 recordable cases per 100 workers per year. Australia, the UK, much of Europe and many global companies report LTIFR and TRIFR per 1,000,000 hours instead; the calculator gives both bases.

Worked example

A site with 480,000 hours worked recorded 6 recordable cases, 3 DART cases and 2 lost-time injuries with 45 days lost. TRIR = 6 × 200,000 ÷ 480,000 = 2.50, DART rate = 1.25, lost-time incident rate = 0.83 and LTIFR = 2 × 1,000,000 ÷ 480,000 = 4.17. The severity rate is 18.75 days lost per 200,000 hours, and the site has the equivalent of 240.0 full-time workers.

Sources: OSHA — Interpretation: how the incidence rate formula (× 200,000) is used · OSHA — Injury and illness recordkeeping

Frequently asked questions

How do you calculate TRIR?

Multiply the number of OSHA-recordable injuries and illnesses by 200,000 and divide by the total hours all employees worked in the period. 6 cases in 480,000 hours gives a TRIR of 2.50.

Why 200,000 hours?

It is the hours 100 full-time employees work in a year (40 hours × 50 weeks), so the rate reads as cases per 100 workers per year.

What is the difference between TRIR and DART?

TRIR counts every recordable case, including those needing only medical treatment. DART counts only the more serious cases that caused days away from work, restricted duty or a job transfer.

What is a good TRIR?

It depends on the industry. The US private-industry average has been around 2.4–2.8 in recent BLS surveys, construction about 2.3–2.5 and office work well under 1. Compare against your industry’s published average.

What is LTIFR?

The lost-time injury frequency rate: lost-time injuries per 1,000,000 hours worked. It is the headline safety metric in Australia, mining and many multinational reports. Divide it by 5 to compare with a 200,000-hour rate.

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This calculator is for educational purposes. Double-check important results before acting on them.