Difference between 1/4W and 1/8W

[bonaparte]

About to order resistors for the first time and don't know which ones to get.

[dconeill]

I'm about to buy a motor vehicle for the first time, which should I choose?

A Ford F150, or
A Toyota Prius?

Moral of the story: what you get kind of depends on what you intend to do with them. If you are buying resistors that have to dissipate less than 1/4 watt, then 1/4 watt resistors will do. If less than 1/2 watt, 1/2 watt resistors will do. If you're following a schematic, that will tell you what size you need. What do you intend to do with your resistors?

Also, resistors are cheap. Buy some of each. But you still need to know how much power they have to deal with.

[eMGee]

The higher the wattage, the bigger the resistor -- if you have room, go for the 1/4W.

HTH

[donh]

volts equals amperes times resistance (e=ir)

power equals volts squared over resistance (watts=V^2/Ohms)=(P=V^2/R)

Now you can figure out what wattage resistor you need.

[Big John Studd]

I buy the bigger ones simply so I can read the color bands!!!

[Montana_Dawg]

When determimning the wattage of a resistor, it always a good rule of thumb to place the nominal wattage toward the middle of the range. For example, if the resistor is to dissipate .10W, then a 1/4W (.25) would be preferable to a 1/8 (.125). The reason for this is heat. The closer the resistor gets to its maximum wattage rating, the more heat it dissipates, the hotter it gets, and the average life of the component decreases. Putting a larger wattage resistor in the circuit is perfectly fine (considering size constraints).