HOS Hours-of-Service Limit Estimator
Three clocks decide when you must stop driving: the 14-hour window, the 11-hour driving limit, and your weekly limit. Enter your numbers and see which clock stops you first.
How the hours-of-service clocks work
If you drive a property-carrying commercial motor vehicle in interstate commerce, three separate hours-of-service clocks run at the same time — and you must obey all three. The federal rules in 49 CFR Part 395 set the limits, your electronic logging device (ELD) tracks them, and a roadside inspector can check them at any time. Running out of hours on any one clock means you may not drive again until that clock resets, even if the other two still have time left. That is why this HOS calculator gives you a quick estimate before you roll, so you can avoid a violation and an out-of-service order.
- The 14-hour duty window — the clock-time window in which all of your driving must fit.
- The 11-hour driving limit — the most time you may spend behind the wheel in one shift.
- The 60/70-hour weekly limit — the most on-duty time you may accumulate over 7 or 8 days.
The 14-hour duty window
Your 14-hour window starts the moment you come on duty after at least 10 consecutive hours off, and it runs on clock time, not on work time. Driving, loading and unloading, fueling, inspections, paperwork and waiting at a shipper all burn the window, and so do meal and rest breaks: the clock does not pause. Once the 14 hours are up, you may not drive again until you have had 10 consecutive hours off, even if you still have driving hours left. In practice this is the clock that catches the most drivers, because a long detention at a dock or a slow unload can eat the window while the truck is standing still.
The 11-hour driving limit
After coming on duty following 10 consecutive hours off, you may drive for no more than 11 hours. Only time actually spent behind the wheel counts toward this limit, so on-duty work that is not driving does not use it up — but it does use up your 14-hour window. When you reach 11 hours of driving, you must stop driving until you have had 10 consecutive hours off, even if your 14-hour window still has time left. Every driving minute adds up.
The 60/70-hour weekly limit
The weekly limit caps all on-duty time, not just driving. Carriers that do not operate every day of the week use a 60-hour limit over 7 consecutive days; carriers that operate every day use a 70-hour limit over 8 consecutive days. Every on-duty hour counts — driving, loading, inspections, fueling and any other on-duty work. The limit is a rolling total, so as older days drop off the 7- or 8-day window, their hours become available again. Once you hit the limit, you may not drive until hours drop off or you take a restart.
The 30-minute break rule
You may not drive after 8 cumulative hours of driving time without first taking a break of at least 30 consecutive minutes. The count is cumulative driving since your last break, not 8 hours on duty: a driver who drives in short stretches reaches the break point later in the day than one who drives straight through. The break itself can be off duty, in the sleeper berth, or on duty but not driving — any 30 minutes not behind the wheel qualifies. Taking the break does not stop your 14-hour window, so most drivers take it at a planned fuel or meal stop.
The 10-hour reset and the 34-hour restart
Ten consecutive hours off duty resets both your 14-hour window and your 11-hour driving limit, and it must be a single unbroken stretch — short naps and split rest do not reset the clocks. Most drivers take this break overnight, whether in the sleeper berth or off duty entirely, and start the next shift with both daily clocks at zero. The weekly clock is different: it resets only after 34 or more consecutive hours off duty, known as the 34-hour restart. The restart is optional, not mandatory — a driver can keep rolling as hours drop off the rolling 7- or 8-day total instead. But when a week has been heavy, a 34-hour restart over a weekend is the simplest way to start the next week with a full weekly clock.
Short-haul and adverse-driving exceptions
Two exceptions in 49 CFR Part 395 help in narrow situations, and neither is a general excuse to drive past the limits. The short-haul exception covers drivers who operate within a 150-air-mile radius of their normal work-reporting location and return there within 14 hours, freeing them from the logbook and ELD requirements when all of its conditions are met. The adverse-driving exception lets a driver extend the 14-hour window by up to two hours when driving conditions the driver did not know about before being dispatched — such as sudden severe weather or an unexpected road closure — make the trip take longer. Both exceptions have strict conditions, and neither lets a driver keep driving when it is unsafe to do so.
Use the estimator above before you start your shift and again whenever your plans change, then compare what it says with your ELD — if the two disagree, trust the ELD and check your numbers. For more free planning help, see the Trucking Tools hub, test your safety knowledge with the Safety Audit Quiz, and look up facilities on the Weigh Station Directory. This page is general information about the federal hours-of-service rules, not legal advice; always follow the current 49 CFR Part 395 text and your carrier’s policies.
Frequently asked questions
What are the three HOS clocks?
The three clocks are the 14-hour duty window, which runs on clock time from the moment you start your shift; the 11-hour driving limit, which is the most time you may spend behind the wheel in one shift; and the 60/70-hour weekly limit, which caps all on-duty time over 7 consecutive days (60 hours, for carriers that do not operate every day) or 8 consecutive days (70 hours, for carriers that operate every day). You must obey all three at once — the tightest one is the one that stops you.
When do I have to take the 30-minute break?
You must take a break of at least 30 consecutive minutes after 8 cumulative hours of driving time, before you drive again. The break can be off duty, in the sleeper berth, or on duty but not driving — any 30 minutes not behind the wheel qualifies. Note that the count is cumulative driving time, not time on duty, and the break does not pause your 14-hour window.
Can I keep working after my 14 hours are up?
Yes, you may do non-driving on-duty work after your 14-hour window ends, but you may not drive again until you have had 10 consecutive hours off. Driving after the window ends is an hours-of-service violation, even if you still have driving hours left under the 11-hour limit.
Is the 34-hour restart mandatory?
No — the 34-hour restart is an optional way to reset the weekly clock. After 34 or more consecutive hours off duty, your 60/70-hour total resets to zero. You can also keep driving as hours drop off your rolling 7- or 8-day total, or stop driving when you reach the weekly limit until hours become available again.