Fans do increase your electricity bill but not by a lot.
Most fans use between 45 to 100 watts and running your fan 24 hours per day would raise your bill by at most $3.00 to $6.00 per month.
That's much cheaper than using an Air Conditioner.
A fans power is low at high speed because it's using more voltage and working harder to move the air.
Fans also use the same amount of electricity whether on low, medium or high but the voltage is dropped when you lower the speed of the fan.
A typical AC powered multispeed fan will use more power at higher speed positions.
The work being done is moving air and at higher speed, more air is moved using more work from the motor.
Keeping it at as low a speed as possible will save more energy.
A fan does not use less electricity on low.
Fans use the same amount of electricity on low, medium and high.
When you change the speed of the fan you just change the voltage drop and not the wattage draw.
A 45w fan uses 45 watts of electricity per hour.
In 24 hours your 45 watt electric fan will use 1,080 watts which is a bit over a KWH which would cost around 10 cents to run if your KWH cost is 10 cents.
Some fans use more electricity than a light bulb.
For example all fans will use more electricity than an LED light bulb while some smaller fans may use less electricity than a 100 watt light bulb.
LED light bulbs use around 9 watts of electricity while fans use around 50 watts to 100 watts of electricity.
The watts that an electric fan uses per hour ranges from 50 watts to as much as 100 watts per hour.
Larger electric fans can use as much as 200 to 300 watts per hour.
The cost to leave a fan on all day depends on the wattage of the fan.
But for example if your electric fan uses 50 watts then it would cost around $3.00 per month to leave your electric fan all day and all month.
If your fan is 100 watts then it usually costs around $6.00 to $7.50 per month depending on your electric rates.
A 50 watt electric fan will use 50 watts of electricity per hour of run time.
In 12 hours the 50 watt electric fan would use 600 watts of electricity and in 24 hours of run time the 50 watt electric fan would use 1,200 watts of electricity.
So if you run your 50 watt electric fan for 24 hours you would use 1,200 watts of electricity which would cost around 10 to 12 cents per day to run per 24 hours.
If your cost of electricity per KWH or 1,000 watts is 10 cents per KWH then the 50 watt electric fan running 24 hours per day 7 days per week for a month would cost around $3.00 per month which is cheap.
Electric fans are pretty cheap to run.
If you have 100 watt electric fan then it would cost around $6.00 to $7.20 per month to run the 100 watt fan.
If your electric fan is 200 watts then it would cost around $14.50 per month to run the electric fan 24 hours per day.
An air conditioner that uses 500 watts per hour would use 12,000 KWH per 24 hours which would cost $1.20 per day or around $36.00 per month.
Fans are cheaper to run than window air conditioners and even central air conditioners.
Central Air Conditioners can use as much as $300.00 to $400.00 per month in electricity depending on your electric rates.