# number of blades on a fan - any significance? **URL:** \ **Category:** Factual Questions\ **Created:** [August 10, 2000, 4:42am UTC](https://boards.straightdope.com/t/number-of-blades-on-a-fan-any-significance/28800 "2000-08-10T04:42:12Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![vandal](https://avatars.discourse-cdn.com/v4/letter/v/858c86/32.png) [@vandal](https://boards.straightdope.com/u/vandal)\ **Post date:** [August 10, 2000, 4:42am UTC](https://boards.straightdope.com/t/number-of-blades-on-a-fan-any-significance/28800/1 "2000-08-10T04:42:12Z")
It’s summer, it’s hot. As such, I have a lot of fans on to keep cool. But, I was wondering about something. Most of the fans I have have 3 blades, but a couple have 4 blades. Does the number of blades make a difference as far as the movement of air goes? I can’t feel any difference. So, I’m wondering, is the number of blades just some arbitrary number that the fan manufacturers choose? Or is there actually some significance behind them? ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 10, 2000, 10:22am UTC](https://boards.straightdope.com/t/number-of-blades-on-a-fan-any-significance/28800/2 "2000-08-10T10:22:10Z")
I imagine one or two simply wouldn’t get the job done, so three works, but four may be more aesthetically pleasing. I would assume the a four-bladed fan would move more air (if it was spinning just as fast.) This WAG has been brought to you by friedo. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [August 10, 2000, 11:21am UTC](https://boards.straightdope.com/t/number-of-blades-on-a-fan-any-significance/28800/3 "2000-08-10T11:21:34Z")
This was answered in “The Last Word” from New Scientist. [What considerations determine how many blades a fan has?](http://www.newscientist.com/lastword/answers/lwa632machines.html) ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [August 10, 2000, 12:53pm UTC](https://boards.straightdope.com/t/number-of-blades-on-a-fan-any-significance/28800/4 "2000-08-10T12:53:40Z")
For 3 or 4 blade “office” fans, the difference is negligible. But when you need to move large volumes of air, more blades are the way to go. But since they are noisier, they’re usually relegated to rooftops or other out-of-the-way places. Jet engine turbine “fans” are a good example. You need high volume (and speed) air flow with little cavitation. So these fans have several dozen very skinny blades. As a result, they’re very noisy. I once worked for a mining fan company in high school. He wanted me to write a computer program to do fan design calculations. But the physics was a little beyond my 11th-grade brain. He had volumes of books on the subject, full of graphs covered with curves. ---
**Author:** ![rocking\_chair](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocking_chair/32/2918_2.png) [@rocking\_chair](https://boards.straightdope.com/u/rocking_chair)\ **Post date:** [August 12, 2000, 3:00am UTC](https://boards.straightdope.com/t/number-of-blades-on-a-fan-any-significance/28800/5 "2000-08-12T03:00:34Z")
five blades are the most stable. stability is very important in a ceiling fan. remote control is fun as well, hunter has remote control, no worries about the string thingy getting caught up in the motor or blades. things not getting caught up in the fan is very important as well, let me tell you. if it is a floor fan there isn’t much diffrence between four and five blades. clip on types are good for spot cooling and drying, they are great for beside your chair or bed.