Normally do it half the time in the Summer and 2/3 in the winter. So the answer is yes. Most devices (Air conditioenrs are the exception) you can check the watts.. Round off watts to the nearest 100, that is right close to your AMPS draw for that device.. NOTE: This applies to heaters, and cooking devices)
Motor driven stuff (Residential Fridge, air compressor) is different.
NOTE: THIS INCLUDES 12 volt stuff.. Since the converter sucks 120vac
Add up what you ahve turne don.. long about 27 stop turning things on.
Air Conditioners, figure 15, no matter what.. You may need to go higher.
Microwave read the ID tage, a 700 watt MW may well draw 1100 watts (an 11).
Most kitchen stuff is in the 7 range.
Hair dryers and space heaters are 12-15