Hours of service, explained plain

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Most hours trouble does not come from a driver trying to cheat. It comes from mixing up the clocks. A driver watches the driving hours, forgets the window, and is surprised when the day ends early. Another driver watches the window, forgets the break, and drives past a rule he thought he had covered. A third driver has a fine day, day after day, and then runs out of week on Friday afternoon.

This guide puts the four main clocks side by side, in plain words, so you can see how they fit together. These are the federal rules for interstate drivers carrying property — freight, not passengers. Passenger-carrying drivers have different numbers, in 49 CFR 395.5; this guide does not use those numbers.

First: 10 hours off before you start

Everything starts with rest. Before driving, a driver must have 10 consecutive hours off duty. Consecutive is the key word. It is one unbroken stretch, not ten hours added up across a day in small pieces. Off duty and sleeper berth time can be combined to make that stretch, and a separate guide on this site explains how a valid split in the sleeper berth can also build the rest in two parts. But the simple, ordinary way is simple: ten hours in a row, off duty, then you come on duty fresh.

That moment — when you come on duty after the 10 hours off — is the moment your other clocks start. It is worth fixing in your mind, because two of the clocks count from it in different ways, and confusing them is where most mistakes begin.

The 14-hour window: a clock that never stops

After coming on duty following those 10 hours off, you may not drive once 14 consecutive hours have passed. If you come on duty at 6:00 in the morning, your window closes at 8:00 in the evening. After 8:00 in the evening, you may not drive, no matter how little driving you have done that day.

The window runs on clock time. It does not run on driving time, and it does not run only while you work. Breaks count inside it. Fueling counts inside it. Waiting at a dock counts inside it. A long lunch counts inside it. Sitting for three hours waiting for a load counts inside it. Nothing pauses the window, except a qualifying split-sleeper pair, which has its own guide. For an ordinary day, picture the window as a kitchen timer set for 14 hours the moment you come on duty. It ticks while you work and it ticks while you wait. When it rings, driving is done for that shift.

This is why a day with a long wait can feel unfair. You may have driven only five hours, rested in the cab, and eaten a slow meal — and still have no window left. The rule does not ask how tired you feel or how hard you worked. It asks how much clock time has passed since you came on duty.

Note what the window does and does not forbid. After the window closes, you may not drive. The rule in 395.3(a)(2) is a driving limit, not a rule that every kind of work must stop at that exact minute. In the worked example below, the driver uses the last part of his window for non-driving work. But once the window is gone, the truck does not move under your hand until you have taken the rest that starts a new day.

The 11-hour limit: driving hours inside the window

Inside that 14-hour window, you may drive at most 11 hours. This clock counts only driving time. Time spent on a pretrip, fueling, loading, or waiting does not use up driving hours — but remember, all of that time does use up the window.

So the two clocks drain at different speeds, and either one can end your driving:

• You run out of drive time with window left. A clean, fast day on open road: you drive 11 hours while the window still has time in it. Driving stops anyway. The 11 is spent.
• You run out of window with drive time left. A day of waiting, traffic, and short hops: the 14 hours pass while you have driven only 7. Driving stops anyway. The window is spent.

Whichever clock hits zero first ends the driving. That one sentence, kept in mind all day, prevents most bad surprises. When you plan a day, plan against both numbers, not just the one that looks closer.

The 30-minute break: after 8 hours of driving

After 8 cumulative hours of driving time, you may not drive again until you have taken a 30-minute interruption. Read that carefully: it is 8 hours of driving, not 8 hours on duty. A driver who spends two hours loading before his first mile has been on duty two hours but has used none of the 8 driving hours that count toward the break.

The interruption can be off duty, time in the sleeper berth, on-duty time that is not driving, or a mix of those. It must be at least 30 minutes. Fueling and doing paperwork as on-duty not driving can therefore serve as the break, as long as no driving happens during it and the full 30 minutes pass before you drive again. Many drivers simply take it off duty with a meal, which is the easiest way to be sure it counts and the easiest way to explain it later.

You may take the break early. Nothing says you must wait until the 8-hour mark is close. In the worked example below, the driver takes his break after 5 hours of driving, well ahead of the deadline, and that settles the break rule for the day. Taking it early is often the smart move when a good stop is in front of you and a bad stretch of road is behind it.

One exception to note: short-haul drivers under 49 CFR 395.1(e) are excepted from this break rule. If your work is under that short-haul exception, the 30-minute break in 395.3(a)(3)(ii) does not apply to you in the same way. Everyone else should plan the break into the day from the start, not discover it at hour seven.

The week: 60 or 70 on-duty hours

The daily clocks reset with rest. The weekly clock is slower and quieter, and it catches drivers who are not watching it. The rule: do not drive after you have been on duty 60 hours in 7 consecutive days, if your carrier does not operate every day of the week — or 70 hours in 8 consecutive days, if your carrier does operate every day of the week.

On-duty here means all on-duty time: driving plus on-duty not driving. The pretrip counts. Fueling counts. Loading, unloading, and waiting on duty count. A day is not just its driving hours; for the week, a day is every hour you were on duty in it.

Hours come back in two ways. The slow way is recap: as each old day falls off the back of the 7- or 8-day count, the hours you worked that day become available again. The fast way is a 34-hour restart: take at least 34 consecutive hours off, and the weekly count starts again from zero. The restart has its own guide, because when it helps — and when it does not — is worth a full page.

Walk through what that day teaches. The break was taken early and never became a problem. The driving limit, not the window, ended the driving — with two hours of window to spare. And the week quietly took 11.5 hours, not 11, because the half hour of pretrip and fuel is on-duty time too. If you had guessed his day by driving hours alone, you would have understated his week by half an hour every single day. Over a week, that is hours you thought you had and do not.

A short drill for the start of any day

1. Fix your start time

   Say out loud when you came on duty after your 10 hours off, and count 14 hours forward. That is when your window closes. Every plan for the day must fit inside it.

2. Count driving and window separately

   Ask two questions, not one: how many driving hours do I have (11 minus what you will use), and how much window do I have? The smaller answer is your real limit.

3. Place the break before you need it

   Pick where the 30-minute break will happen before the 8th hour of driving arrives. Early is fine. A planned stop beats a desperate one.

4. Add the whole day to the week

   Before you start, add today's expected on-duty hours — driving and non-driving together — to your week total. If the week is nearly full, today is the day to know it, not tonight.

The three traps, stated plain

The window does not stop for breaks. Resting, eating, waiting, and fueling all happen inside the 14 hours. A break helps the break rule and can help the driver; it does not buy back window time.

The break clock counts driving only. Eight hours on duty with three hours of driving is three hours toward the break deadline, not eight. Do not take a break you do not yet need out of confusion — and do not skip one you do need because the day felt short on duty time but was long on driving.

The week counts all on-duty time. Every on-duty hour, driving or not, goes onto the 60 or 70. Drivers who count only driving are borrowing hours from a week that will collect the debt on the worst possible day.

Hold those three sentences and the four clocks together, and the rules stop being a pile of numbers. They become one picture: rest first, a window that always ticks, driving hours inside it, a break in the middle of the driving, and a week that remembers everything.

Rules checked October 2026. Rule sources: 49 CFR 395.3; 49 CFR 395.1(e).