# How to calculate heat in wire?

I'm fairly new to electronics, but I understand the relation between current resistance and voltage. I wanted to make a heating element for a project of mine. I have a spool of 14 awg bare copper wire, but I don't know how many amps I need. I'd like to get the heat output on the wire to 60-70 watts. If anyone could tell me a formula or relation between current and/or resistance and wattage, that would be great.

• $P={{I^2}R}$. Electronics 101. – Ignacio Vazquez-Abrams Oct 3 '16 at 20:55
• .. and about 2.525 milli-ohms per foot for #14 copper – brhans Oct 3 '16 at 21:04
• 100 ft spool" 252.5 mOhms into 65W= 16A the. V=IR = 4V – Tony Stewart EE75 Oct 3 '16 at 22:11
• It is easier using resistance wire , Nichrome or use 5V CPU power supply and use 125 ft. or use 12V PSU and lighter gauge magnet wire – Tony Stewart EE75 Oct 3 '16 at 22:12
• Or stainless steel wire. – mkeith Oct 4 '16 at 3:16

For example, if you design it for 1A you will need 65 ohms (and 65V), which is 65$\Omega$/8.286m$\Omega$/m = 7.8km of AWG14 wire. Not very practical.