Once a year for a typical household. That is the baseline the Consumer Product Safety Commission, the National Fire Protection Association and most dryer manufacturers all land on, and for a lot of homes it is the whole answer.

What moves the number is how much air has to travel through the duct, and how hard that air has to work to get out.

A schedule that fits the house

• One or two people, a few loads a week. Every twelve to eighteen months is usually honest.
• A typical household. Annually.
• More than about five loads a week, or pets, or a lot of towels and bedding. Every six months. Lint accumulation tracks load count far more closely than it tracks the calendar, and pet hair packs denser than clothing lint once it settles.
• A long run, an attic-to-roof run, or a concealed section of flexible foil. Every six months, and the foil should be replaced.

Nobody can give you a number that is right for every house, which is why the useful version of this question is not how often, but what does my particular duct do.

Why the interval runs shorter here

Humid air makes dryers work longer. Longer cycles push more lint through the duct, so a South Florida household running the same number of loads as one in a dry climate puts more into the vent line over a year.

There is also no off-season. National advice often suggests scheduling in spring or fall, which assumes a period of lighter use. Here the dryer runs at the same rate in August as in January, and beach towels and pool laundry push the summer months higher rather than lower.

Coastal buildings add a third factor. Salt air corrodes exterior vent hoods and dampers, and a damper that no longer swings freely restricts airflow even when the duct behind it is clear.

Duct length is the variable nobody checks

Code puts a ceiling on how long a dryer duct can be. The standard maximum is thirty-five feet of developed length, and every bend counts against it: roughly five feet deducted for each ninety-degree elbow and two and a half feet for each forty-five. A run with three ninety-degree turns has spent fifteen of its thirty-five feet before it covers any distance.

Plenty of laundry rooms in older coastal condo buildings sit toward the center of the floor plan and vent horizontally to an exterior wall. Those runs can approach or exceed forty feet before you count the elbows. If that describes your unit, annual cleaning is a floor rather than a target, and it is worth knowing whether the run is legal at all before you assume the dryer is the problem.

If you do not know where your duct goes or how far it travels, that is worth establishing once. See how to find your dryer vent.

What a cleaning has to include for the interval to mean anything

An interval only counts if the cleaning actually reset it. A service that clears the first several feet behind the dryer and leaves the rest of the run packed has not bought you twelve months. It has bought you a receipt.

A cleaning that resets the clock covers the transition duct behind the machine, the full concealed run, and the exterior hood and damper. It ends with the dryer running and airflow confirmed at the outside vent, so the result is something you can see rather than something you are told. We describe the full process on the dryer vent cleaning page.

Signs you are already overdue

The interval is a guideline. These are facts:

• Clothes need more than one cycle
• The dryer or the room is noticeably hot after a load
• The flap on the exterior vent hood barely moves while the dryer runs
• There is a musty smell in the laundry area
• The dryer shuts off before the cycle ends
• Lint is collecting around the outside vent or behind the machine
• The dryer is displaying an airflow, heating, or temperature code

That last one is worth taking seriously. LG dryers with Flow Sense report duct blockage as a percentage. Samsung lists a clogged lint screen or vent as the most common cause of its heating and temperature codes. Whirlpool uses a restricted-airflow code. When the appliance itself is telling you the duct is blocked, the interval question is already settled. See dryer error codes by brand.

The lint trap is not the vent

These get treated as the same job and they are not. The lint screen catches what it can at the drum, and it should be cleared after every load. Everything the screen misses goes into the duct, where it settles at elbows, sags and low points and stays there. Emptying the trap diligently for a decade does nothing for the run behind the wall.

What you can do between cleanings

• Clear the lint screen after every load, not every few loads
• Once a month, run the dryer and check that the exterior flap opens fully and holds steady
• Look at the outside hood for lint at the edges, debris, or a nest
• Leave a few inches behind the dryer so the transition duct is not crushed against the wall
• Wash the lint screen with warm water once or twice a year if you use dryer sheets, which leave a film that restricts airflow through the mesh

None of this replaces cleaning the run. It does tell you early when something has changed.

Check your warranty before you skip a year

Some manufacturers now require documented annual vent cleaning as a condition of honoring a warranty claim, on the reasoning that most heat-related component failures trace back to restricted airflow. If your dryer is still under warranty, it is worth reading that section before deciding the interval does not apply to you. A denied claim on a control board costs considerably more than a cleaning.

What if it has never been cleaned

Then it is due now, regardless of how the dryer seems to be running. First cleanings on a run that has gone ten or fifteen years are the ones that produce the most obvious change in drying time, and they are also where we find the collapsed foil, the crushed transition duct and the exterior hood packed solid.

Why the interval matters beyond drying time

Lint is combustible, and a restricted vent makes the dryer run hotter than it was designed to. Those two conditions together are the mechanism behind dryer fires, and failure to clean is the leading cause of them. Cleaning on a schedule removes one of the two.

It also takes strain off the appliance. A dryer fighting a blocked duct runs longer and hotter every cycle, which shortens the life of the heating element, the thermostats and the thermal fuse, and eventually the control board. That is the quiet cost of stretching the interval, and it usually arrives as a repair or replace decision years earlier than it should have.

One honest caveat. A clean duct lowers the risk, it does not eliminate it. Vents have caught fire on runs cleaned weeks earlier, because the duct material, the exterior termination and the condition of the machine all matter too. Frequency is the variable you control most easily, not the only one that counts.