How to check resistor wattage

[irfan bangash]

How to check resistor watt ?

some R is big or some R size is small , how i chk R is 1watt 2watt 1/2watt 1/4watt ?

 

[cowboybob]

For the most part it is a matter of size (diameter)

These are approximations, but fairly close estimations.

A resistor that has a diameter more or less the equivalent to the spray tube of an aerosol can is probably 1/8W.

Each successive doubling in size are 1/4, 1/2 and 1W.

 

[crutschow]

Look up a similar physical size resistor and note its power rating. That will be the rating of your resistor.

 

[ronsimpson]

The 1% resistors are usually one size bigger than 5% parts.

 

[crutschow]

The 1% resistors are usually one size bigger than 5% parts.

Good point.