A lost time injury (LTI) is a workplace injury or illness serious enough that the affected worker misses at least one full day of work beyond the day the incident occurred. It’s one of the most widely tracked safety metrics in occupational health, used by companies, regulators, and insurers to measure how well a workplace protects its people. If an employee gets hurt on the job Tuesday and can’t come back Wednesday, that’s a lost time injury, and it triggers specific recording and reporting requirements.
What Counts as a Lost Time Injury
The defining feature is simple: the injured worker cannot return to work for one or more days after the injury. The count begins the day after the incident, not the day it happens. So if a warehouse worker strains their back on a Monday and their doctor tells them to stay home through Friday, that’s four lost days (Tuesday through Friday).
The count includes calendar days, not just scheduled shifts. Weekends, holidays, and vacation days all get counted if the worker wouldn’t have been able to work on those days because of the injury. A Friday injury that keeps someone out through the following Monday counts as three lost days (Saturday, Sunday, Monday), even though Saturday and Sunday weren’t workdays.
One important detail: the days are counted based on a doctor’s recommendation, regardless of whether the employee actually follows it. If a physician recommends five days off and the worker comes back after two, the employer still records five lost days. The maximum recording cap is 180 calendar days. For injuries that keep someone out longer than six months, employers can simply enter 180 on the log.
How LTIs Differ From Other Injury Categories
Not every workplace injury is a lost time injury. OSHA classifies recordable incidents into a hierarchy based on severity:
- First aid cases: Minor injuries treated with bandages, ice packs, or over-the-counter medication. These don’t require formal recording.
- Medical treatment injuries: Injuries that need care beyond first aid (stitches, prescription medication, physical therapy) but don’t result in missed work or job restrictions.
- Restricted work cases: The worker returns to the job but can’t perform all their normal duties. A construction worker with a wrist sprain who comes back but is limited to paperwork falls into this category.
- Lost time injuries: The worker misses one or more days entirely. This is the most severe non-fatal category and carries the most weight in safety performance metrics.
The distinction between a restricted work case and an LTI matters because companies often track them separately. An employer might bring an injured worker back on light duty specifically to avoid recording a lost time injury, which is legal as long as the worker can meaningfully perform the modified role.
How Companies Calculate LTI Rates
Raw counts of injuries don’t tell you much on their own. A company with 10,000 employees will naturally have more incidents than one with 50. To make meaningful comparisons, organizations use standardized formulas.
The most common is the Lost Time Injury Frequency Rate (LTIFR). The formula multiplies the number of lost time injuries by 200,000, then divides by the total employee hours worked. The 200,000 figure represents a baseline of 100 employees working 40 hours a week for 50 weeks. So if a company with 500,000 labor hours in a year had three lost time injuries, the calculation would be (3 × 200,000) ÷ 500,000 = 1.2. That means 1.2 lost time injuries per 100 full-time workers per year.
A separate metric, the severity rate, captures how bad the injuries actually were. It divides total lost workdays by total recordable incidents. A company might have a low frequency rate but a high severity rate if their rare injuries tend to be serious ones that keep people out for weeks.
Industry Benchmarks
Injury rates vary dramatically by industry. Bureau of Labor Statistics data for 2024 shows total recordable injury and illness rates per 100 full-time workers of 2.2 in construction, 2.7 in manufacturing, and 3.4 in healthcare and social assistance. Healthcare’s higher rate surprises many people, but the sector deals with patient handling injuries, needlestick exposures, and workplace violence at rates that push it above traditionally “dangerous” industries.
These figures cover all recordable incidents, not just lost time cases. Lost time injuries make up a subset of that total. Companies typically aim for an LTIFR well below their industry average, and many in sectors like oil and gas or mining set internal targets approaching zero.
Recording and Reporting Requirements
In the United States, employers log lost time injuries on OSHA Form 300, a running log of all work-related injuries and illnesses throughout the year. Each lost time case gets a check mark in the “days away from work” column, along with the number of calendar days missed. A companion form, the 300A, summarizes annual totals and must be posted in the workplace each February through April so employees can see it.
Employers can use equivalent formats like spreadsheets instead of the official paper forms, as long as the same data fields are captured. Covered establishments submit their 300, 300A, and individual incident data (Form 301) electronically through OSHA’s Injury Tracking Application. OSHA does not accept paper submissions by mail or electronic forms by email.
If an injured employee leaves the company because of the injury, the employer must estimate the total days that would have been lost and record that number. If the employee leaves for an unrelated reason, like taking a different job or retiring, the employer can stop counting.
The Financial Cost of Lost Time Injuries
The direct costs of an LTI, primarily workers’ compensation claims, are only part of the picture. OSHA’s Safety Pays estimator uses an indirect cost multiplier on top of direct claim costs to capture the less obvious expenses: hiring and training replacement workers, lost productivity, administrative time spent on investigations and paperwork, potential equipment damage, and the ripple effects on team morale and schedules.
How much an employer pays out of pocket for direct costs depends on their insurance structure, but indirect costs always fall on the employer. OSHA’s model factors in a company’s profit margin to estimate how much additional revenue the business would need to generate just to break even on a single injury. For many companies, especially those operating on thin margins, a handful of serious lost time injuries in a year can represent a significant financial burden that no amount of extra sales easily offsets.
How LTIs Are Tracked Outside the US
The concept of a lost time injury exists globally, but definitions vary. In the United Kingdom, the Health and Safety Executive tracks working days lost and calculates rates per full-time equivalent worker rather than per 200,000 hours. The UK system also distinguishes between injuries causing over three days of absence and shorter ones, with longer absences triggering more stringent reporting under RIDDOR (the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations).
Australia, Canada, and many international oil and gas companies use the same basic LTIFR formula with the 200,000-hour (or sometimes 1,000,000-hour) multiplier. The core idea is consistent everywhere: when someone gets hurt badly enough that they can’t show up to work the next day, it represents a failure in safety systems that needs to be counted, investigated, and prevented from happening again.