# LTIFR and Injury Severity Rate Calculator

> Source: https://netray.co/tools/ltifr-severity-rate-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Compute lost time injury frequency rate, severity rate and average days lost per injury on the hours basis your company or customer uses.

## Category

ehs-workforce

## Industry

Manufacturing

## Audience

- Safety manager
- EHS coordinator
- Plant manager

## Tool

**Kind:** calculator

**Inputs:**

#### Lost time injuries in period

**Key:** lti

**Type:** number

**Default:** 3

**Min:** 0

**Step:** 1

**Unit:** cases

**Help:** Cases that resulted in at least one lost day or shift under your definition.

#### Total days lost in period

**Key:** days

**Type:** number

**Default:** 46

**Min:** 0

**Step:** 1

**Unit:** days

**Help:** Use scheduled work days or calendar days consistently with your policy.

#### Total hours worked in period

**Key:** hours

**Type:** number

**Default:** 520000

**Min:** 1

**Step:** 1000

**Unit:** hours

**Help:** All employees, including overtime and, if policy says so, contractors.

#### Rate basis

**Key:** basis

**Type:** select

**Default:** 1000000

**Options:**

##### Per 1,000,000 hours

**Value:** 1000000

##### Per 200,000 hours

**Value:** 200000

##### Per 100,000 hours

**Value:** 100000

#### Target LTIFR

**Key:** target

**Type:** number

**Default:** 3

**Min:** 0

**Step:** 0.1

**Help:** Your company or customer target on the same basis.

**Outputs:**

#### LTIFR

**Key:** ltifr

**Expr:** lti * basis / hours

**Format:** decimal

**Primary:** true

**Description:** Lost time injuries x basis / hours worked.

#### Severity rate

**Key:** sr

**Expr:** days * basis / hours

**Format:** decimal

**Primary:** true

**Description:** Days lost x basis / hours worked.

#### Average days lost per injury

**Key:** avg

**Expr:** days / max(lti, 1)

**Format:** decimal

#### Gap to target

**Key:** gap

**Expr:** ltifr - target

**Format:** decimal

**Description:** Positive means worse than target.

#### Maximum injuries allowed at target

**Key:** allow

**Expr:** floor(target * hours / basis)

**Format:** integer

**Description:** Whole injuries that keep the period at or below target.

**Chart:**

#### LTIFR by number of lost time injuries

**Type:** line

**X:** lti

**From:** 0

**To:** 12

**Steps:** 13

**Series:**

- ltifr

**Disclaimer:** Definitions of lost time injury, day counting and included workers vary by country, company and customer. Use the definition your contract or regulator specifies.

## Content

**Intro:** LTIFR and severity rate are the headline safety KPIs for many manufacturing groups, mining and construction clients, and supplier audits outside the US. This calculator keeps the arithmetic and the basis consistent.

**Sections:**

#### How to use it

**Body:** Enter the lost time injuries, total days lost and total hours worked for the same reporting period and the same population. Pick the rate basis your group uses. Many European and Australian companies report per million hours, US OSHA statistics use 200,000 hours, and some older systems use 100,000. Add your target to see the gap and the number of injuries you can afford before breaching it. The chart shows how the rate rises with each additional case on your hours base.

#### The formulas

**Body:** LTIFR = lost time injuries x basis / hours worked. Severity rate = days lost x basis / hours worked. Average days per injury = days lost / lost time injuries. Because the same hours base sits in both rates, severity rate divided by LTIFR returns the average days per case. A site with a very low frequency but a high average days figure is having few but serious injuries, which a frequency number alone hides.

**Bullets:**

- Keep the basis constant in a trend report
- Report both rates, not one
- Define how days are counted before comparing sites

#### Reading the output

**Body:** Compare frequency to a target and severity to the history of your own plant. Small plants swing sharply: with 150,000 hours a year, one injury at the million-hour basis gives an LTIFR near 6.7, so use rolling twelve-month figures and show the case count beside the rate. The allowed-injury output turns an abstract target into a number a supervisor can act on, such as two cases for the year.

#### Common mistakes

**Body:** The usual errors are mixing contractor hours into the denominator but not their injuries, comparing a million-hour rate with a 200,000-hour rate, and counting restricted work days in one place but not another. Also remember that a rate rewards under-reporting. Pair it with near miss counts and leading indicators so a quiet year is not mistaken for a safe one.

**Cta:** If hours worked sit in payroll and incident data sits in another system, we can help build a monthly safety KPI view over your ERP data without manual copy and paste.

**Faq:**

#### What is the LTIFR formula?

**Answer:** LTIFR equals the number of lost time injuries multiplied by the rate basis, usually 1,000,000, divided by the total hours worked in the period. Use the same period and population for the numerator and the denominator.

#### What is the difference between LTIFR and TRIR?

**Answer:** LTIFR counts only injuries that cause lost time. TRIR counts all recordable cases, including medical treatment and restricted work, and is usually on a 200,000-hour basis. They answer different questions, so do not substitute one for the other.

#### How is severity rate different from frequency rate?

**Answer:** Frequency rate shows how often lost time injuries happen. Severity rate shows how many days were lost per unit of exposure. A plant can have a low frequency and a high severity if a few cases are serious.

#### Which hours basis should I use?

**Answer:** Use whatever your corporate group, customer or regulator requires. A million-hour basis is common internationally, 200,000 hours is typical for US OSHA based reporting. Never compare rates calculated on different bases.

## Search terms

ltifr calculator, lost time injury frequency rate formula, injury severity rate calculator, frequency rate per million hours, average days lost per injury, safety kpi calculator, lti rate calculation, accident frequency rate formula

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