Oven output wattages can vary by up to 30% from their rated wattages. Either of the following two methods can provide a more accurate measure of an oven's wattage. Finally, knowing the wattages of your different power levels can help make better use of your oven.
__Time Method__
Note the amount of time it takes for one cup (250 ml) of water to boil at full power, then look up the wattage in this chart:
5'50" 300 watts 1'45" 1000 watts
4'20" 400 watts 1'35" 1100 watts
3'30" 500 watts 1'25" 1200 watts
2'55" 600 watts 1'20" 1300 watts
2'30" 700 watts 1'15" 1400 watts
2'10" 800 watts 1'10" 1500 watts
1'55" 900 watts 1'05" 1600 watts
__Temperature Method__
Measure the temperature of one quart (1 l) of water, then heat it with full power for 61 seconds. Stir, then measure the temperature again, and then multiply the difference by 44 (79 for centigrade). (The industry changed its method of rating wattage in the early 90s, making the ratings higher. To see the actual wattage the food is getting multiply by 39 for Fahrenheit, or 70 for Centigrade.)
__Power Level Wattages__
The wattage of a power level is: [power level] x 0.1 x [wattage of oven].
If the oven has descriptive power levels substitute these numbers for these descriptions:
10 = full/high
7 = medium high/bake/roast
5 = medium/braise
3 = low/simmer/defrost
