To calculate your DART rate, multiply the number of DART cases by 200,000, then divide by the total hours all employees worked during the period. The result tells you how many serious workplace injuries or illnesses occurred per 100 full-time workers in a year, giving you a standardized number you can compare across companies, job sites, and industries.
The DART Rate Formula
The formula is straightforward:
DART Rate = (Number of DART cases × 200,000) ÷ Total hours worked by all employees
The 200,000 multiplier represents the total hours 100 employees would work in a year (40 hours per week, 50 weeks per year). OSHA uses this number as a standard base so that a small company with 15 workers and a large operation with 5,000 can be compared on equal footing. Without it, raw case counts would be meaningless across different workforce sizes.
Here’s a quick example. Say your company recorded 4 DART cases over the past year, and your employees worked a combined 500,000 hours. The math: (4 × 200,000) ÷ 500,000 = 1.6. That means for every 100 full-time workers, you’d expect about 1.6 serious injuries or illnesses per year.
What Counts as a DART Case
DART stands for Days Away, Restricted, or Transferred. A case qualifies if a work-related injury or illness results in any of the following outcomes:
- Days away from work: The employee misses one or more scheduled workdays because of the injury or illness.
- Restricted work: The employee stays on the job but can’t perform one or more routine functions, or can’t work a full scheduled shift. A “routine function” is any activity the employee regularly performs at least once per week. A restriction counts whether it’s imposed by the employer or recommended by a healthcare professional.
- Job transfer: The employee is reassigned to a different job, even for part of a day. The day the injury occurs doesn’t count; the transfer has to extend beyond that initial day.
On OSHA’s Form 300A (the annual summary log), DART cases are tallied from Column H (days away from work) and Column I (job transfer or restriction). Each incident is counted once, even if a single injury results in both missed days and restricted duty afterward. You’re counting cases, not days.
How to Count Total Hours Worked
The denominator in the formula requires accuracy. Include hours actually worked by all employees: salaried, hourly, part-time, seasonal, and any temporary workers you supervise (including those supplied by a staffing agency). Overtime hours count too.
Do not include vacation time, sick leave, holidays, or any other paid time off. Even if employees were paid for those hours, they weren’t working and weren’t exposed to workplace hazards, so the hours don’t belong in the calculation. If your payroll system only tracks hours paid rather than hours worked, OSHA requires you to estimate actual hours worked. For salaried employees who don’t clock in and out, a reasonable estimate based on their typical schedule is acceptable.
A Step-by-Step Example
Suppose you’re calculating the annual DART rate for a manufacturing facility. Here’s how to walk through it:
First, pull your OSHA 300 Log and count the entries with a check mark in Column H or Column I. Let’s say you find 7 cases: 3 where the employee missed work entirely, 2 where they were placed on light duty, and 2 where they were temporarily moved to a different role.
Next, calculate total hours worked. Your facility has 120 employees. Most worked close to full-time schedules, and after removing PTO and holidays, your payroll department estimates 210,000 total hours for the year.
Now plug in the numbers: (7 × 200,000) ÷ 210,000 = 6.67. That’s your DART rate. For every 100 full-time equivalent workers, roughly 6.67 experienced a serious enough injury to miss work, be restricted, or be transferred.
Industry Benchmarks to Compare Against
A DART rate means very little in isolation. You need context. The Bureau of Labor Statistics publishes industry-specific rates annually using data from employers nationwide. The 2024 figures for some common industries:
- Construction: 1.3 per 100 full-time workers
- Manufacturing: 1.7
- Health care and social assistance: 1.7
If your rate is significantly above the average for your industry, it signals that your workplace is producing more serious injuries than comparable operations. In the manufacturing example above, a DART rate of 6.67 would be nearly four times the national average, a clear red flag. Contractors and clients increasingly use DART rates as qualification criteria for bidding on projects, so a high number can cost you business opportunities in addition to indicating safety problems.
DART Rate vs. Total Recordable Incident Rate
DART rate and TRIR (Total Recordable Incident Rate) use the same formula structure but measure different things. TRIR captures every recordable workplace injury or illness, including minor ones that required only medical treatment beyond first aid. DART filters for severity, counting only cases where the worker couldn’t do their normal job afterward.
Think of TRIR as a measure of how often injuries happen at all. DART tells you how often injuries are serious enough to disrupt work. A company could have a moderate TRIR but a very low DART rate, meaning injuries occur but rarely result in missed time or job changes. Conversely, a company with a low TRIR but a DART rate close to it likely has few incidents overall, but the ones that do happen tend to be serious. Most safety professionals track both because together they reveal whether your problem is frequency, severity, or both.
Reporting Requirements
OSHA requires certain employers to submit injury and illness data electronically through its Injury Tracking Application. The rules apply at the establishment level, not the company as a whole. Establishments with 20 or more employees in certain industries must submit Form 300A data annually. Those with 100 or more employees in industries listed in OSHA’s Appendix B must also submit detailed information from Forms 300 and 301, a requirement that took effect in 2024.
Establishments with fewer than 20 employees at peak staffing during the previous year are exempt from electronic reporting, as are those in industries specifically excluded under OSHA’s recordkeeping appendices. Even if you’re exempt from electronic submission, keeping an accurate 300 Log and calculating your DART rate remains a practical tool for spotting safety trends before they become costly patterns.