How do I calculate the resistance needed to make a "heater"?

I plan on making a heater out of resistors, I have no clue on how to calculate this, I can supply it with 12VDC up to 5 amps. I don't plan on making this on a large scale The future purpose of this fingertip and toe warmer. Any, if all help is appreciated! :)

sort by: active | newest | oldest
110100101108 years ago
how much power you want ? i think 2 - 4 W is about whats need to warm your toe

now 2 W / 12 V = about 170 mA

12 V / 170 mA = about 0.06 Kohm = 60 ohm

think how much resistors you want to use and how much watts each is

say you have 1/2 W resistors. you can load each with at most 1/2 W. for 2 W you need atleast 4 resistors

you can use for example

15 ohm resistors in series
240 ohm resistors in parallel
60 ohm resistors in 2 X 2

or nicrome wire of total resistance 60 ohm - as redrockers said
110100101108 years ago
if its same resistance as the resistors it'll make the same amount of heat
junits15 (author)  110100101108 years ago
ok so I want to run this on twelve volts I set the wattage by the amount of resistors i use, and ampers needed is calculated by Amps = Watts/Volts. I could run this on batteries right, origionally i was going to run it on a regulated power supply but I don't think i even need to.
the sum power is chosen by you the amount of resistors determines how much of it each resistor takes - as in 4 1/2 W resistors give 2 W togethr dont delete your previous replies
110100101108 years ago
it can be designed for any voltage. if you allready have a power source you'd like to use then design for its voltage
Redrockers8 years ago
just use some nichrome wire