Random Drug Testing Calculator
Enter your covered pool, your annual testing rate, and how often you draw. This works out how many tests your program needs per year and per selection, so you can see whether your schedule actually delivers the rate your policy promises.
Reading the Result
The tests-per-year figure is what your policy has committed you to. The tests-per-selection figure is the operational number: it is how many people have to be notified, tested, and tracked each time you draw, and it is the one that tells you whether your schedule is realistic.
The third figure is the one employees care about. If a person in the pool has a one-in-four chance of selection in a year, then some of them will be selected twice in a row, and someone will conclude they are being targeted. Knowing the number in advance makes that conversation much easier.
Want the pool, selections, and tracking run for you?Five questions, about a minute. A specialist follows up within one business day.
Request a SpecialistWhat the Calculator Cannot Tell You
- Whether your rate is right. That comes from your risk, your industry, and your regulator if you have one.
- Whether your pool is correct. Most programs fail here rather than on arithmetic, because the roster drifts and nobody reconciles it.
- Whether you will meet it. A rate in a policy and a rate in your completion records are different things, and only the second one matters when the program is questioned.
Regulated Programs
If your program is federally regulated, the rate is set for you and can change from year to year, so check the current figure for your agency rather than a number from a previous year. The arithmetic here still applies; only the input changes.
Common questions
Where does the number come from?
Straight arithmetic: your covered pool multiplied by your annual rate gives tests per year, divided by your number of draws gives tests per draw. Nothing is rounded up or down for you, because whether you round is a policy decision. Most programs round up, since falling short of your own stated rate is the worse error.
What rate should we use?
Federally regulated programs have rates set annually by the agency that regulates them, so use the current figure for yours. Non-regulated programs choose their own, and the right answer is one you will actually meet every year. See setting up a random program for how to decide.
Does the pool change during the year?
Almost always, which is why this is a planning figure rather than a fixed target. Your pool should be reconciled against your roster continuously, and the tests-per-draw number recalculated as the covered population moves. In a high-turnover workforce, that drift is significant.
Why spread draws across the year?
Because unpredictability is the entire mechanism. A single annual draw is predictable in practice even if the names are random, and clustering selections at year end to catch up is conspicuous and hard to defend. Quarterly is the common compromise; monthly suits larger pools.
Have Your Random Program Run for You
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Sources and review
- 49 CFR Part 382 - Controlled Substances and Alcohol Use and Testing (eCFR)
- SAMHSA - Drug-Free Workplace employer resources
This page is general information about employer drug testing, not legal advice. Drug testing rules differ by state and by industry. Check with your own counsel before setting or changing a testing policy.