Home / Blog / Dryer vent length and bends
Dryer Vent Length and Bends: What the Manual and Code Say
How long can a dryer vent be, and what does each bend cost you? Here is how the manual and the model code set the limit, with worked examples.
Last reviewed October 1, 2026. Written and reviewed by the Plano Dryer Pros team. How we create content
Your dryer’s manual sets the maximum vent length, and it governs. Where it is silent, the model residential code allows 35 feet of duct, reduced by 5 feet for each 90-degree bend and 2.5 feet for each 45-degree bend. A shorter, straighter run moves air better, and a long run with many bends needs more frequent cleaning.
Key takeaways
- The dryer manual sets the maximum length, and it governs.
- The model residential code defaults to 35 feet, minus 5 feet per 90-degree bend and 2.5 feet per 45-degree bend.
- Every bend shortens the run you can use, so fewer and gentler bends are better.
- A long or bent run needs more frequent cleaning, and local code may differ.
The rule in one table
| Item | Typical allowance |
|---|---|
| Maximum straight length (model code default) | 35 feet |
| Each 90-degree elbow | Reduces the maximum by 5 feet |
| Each 45-degree elbow | Reduces the maximum by 2.5 feet |
| The dryer manual | Sets its own maximum, and it governs |
| Local building code | May adopt or amend the model code, so check it |
How long can a dryer vent be?
The dryer manual sets the maximum length, and it governs. Where the manual does not say, the model residential code defaults to 35 feet of duct, reduced for each bend. Local code can differ, so check it. A shorter, straighter run moves air better, and a long run needs more frequent cleaning.
Worked examples
| Run | Calculation | Allowed straight length left |
|---|---|---|
| Straight to the wall, no bends | 35 feet | 35 feet |
| Two 90-degree bends | 35 minus 10 feet | 25 feet |
| One 90-degree and two 45-degree bends | 35 minus 5 minus 5 feet | 25 feet |
| Four 90-degree bends | 35 minus 20 feet | 15 feet |
How many bends can a dryer vent have?
There is no fixed number, because each bend takes away part of the allowed length. Under the model code default, a 90-degree bend costs 5 feet and a 45-degree bend 2.5 feet, so a run with several bends must be much shorter. The manual for your dryer sets the real limit.
What makes a run work better
- Use rigid or semi-rigid metal duct, not thin foil or vinyl
- Keep it short, and as straight as the room allows
- Use gentle, wide bends instead of sharp elbows
- Secure joints with foil tape or clamps, and avoid screws that stick into the duct
- End at a hood with a flap and no screen
Does a longer vent make my dryer slower?
Yes. Every extra foot and every bend adds resistance, so a long run moves less air and clothes take longer to dry. A run near its limit also collects lint faster. If a long run is the cause, shortening it or re-routing it is a better fix than adding a booster fan.
What if my vent is longer than allowed
A run over the limit restricts airflow, which leads to long drying times, overheating, blown fuses and a higher fire risk. The fixes are to shorten it, remove bends, use smoother duct, or in some cases fit a booster fan that the manual and code allow. A technician can measure the airflow and advise. See the vent safety guide.
Is a vent booster fan the answer to a long vent?
Sometimes, but only if the manual and local code allow it. A booster fan can help move air through a long run, but it can also catch lint and needs regular cleaning. Often a shorter, straighter duct is the better fix. Ask a technician to measure the airflow before you choose.
Sources
- National Fire Protection Association, Clothes Dryers and Washing Machines fact sheet (2010 to 2014 annual averages)
- Your dryer’s installation and service manual, which governs over any general guidance on this page
- Plano Dryer Pros estimates of typical local repair pricing, checked against national consumer cost guides for context. See our Editorial Policy.
Frequently asked questions
Does the 35-foot rule apply to every dryer?
No. It is the model code default, and your dryer’s manual may set a different maximum, which then governs. Local building codes can also differ, so check the manual and ask the local authority if you are building or altering a run.
How do I measure my dryer vent length?
Measure the duct from the back of the dryer to the outside hood along the route it takes, then subtract the allowance for each bend. A tape measure works for an exposed run, and for a hidden run, a technician can trace and measure it.
Does the hood count toward the length?
Check the manual and code, because some count the hood and some treat it separately. Either way, a clear hood with no screen matters more than the exact count, because a clogged hood restricts airflow as badly as a long duct.
Can I run a dryer vent up through the roof?
It is possible, but vertical and roof runs are harder to clean, collect lint at the turns and can trap moisture. They count toward the length and bends, and the roof hood needs a flap that closes. Ask a technician about the run first.
What diameter should the duct be?
Most dryers use 4-inch duct, but your manual governs. Keep the same diameter from the dryer to the hood, because a narrower section restricts airflow. Avoid transitions to a smaller size along the run.
Get your dryer working again
Call and a person will answer, or request a repair online. You get the full price in writing before any work starts.