I Need To Plug Something Into A Gas Powered Generator . It Uses 25 Amps. How Many Watts Of Power Do I Need From The Generator?

watts are amps multiplied by volts

How to Convert Watts to Amps Simplified -- Converting Amps to Watts the easy way (http://www.powerstream.com/Amps-Watts.htm)

The conversion of Amps to Watts is governed by the equation Watts = Amps x Volts

For example 1 amp * 110 volts = 110 watts

multiplied by 25 would mean 2750 watts

Hopefully someone else will comment. I'm not an electrician.

Is the generator putting out 110 volts or 220??

I Need To Plug Something Into A Gas Powered Generator . It Uses 25 Amps. How Many Watts Of Power Do I Need From The Generator??
Oneguyinohio is spot on with his comments and calculations.
The POWER needed is indeed 2750 Watts. Irrespectively if the generator produces 110Volt or 220Volt, although the voltage is important to match generator with the used appliance.
If you still have to buy both, go for a higher voltage or dual voltage system : the lower the current (i.e. the higher the voltage) the lower the loss in the wiring. A dual voltage two phase generator (110-0-110) has the advantage that you can also connect other appliances to the generator.
;)