How to Calculate Amps for a Breaker Box
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Determine the size of wiring in your circuits. A 14-gauge wire has a 15 amp rating. A 12-gauge wire has a 20 amp rating.
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Check that each breaker has the same amp rating as the wire ratings. They can have different wiring and amp capabilities, but each should not exceed the number of amps that the breaker can handle. You'll find this number on top of the toggle switch. It may also have a bar that connects two switches on the same breaker.
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The standard voltage for a home is 120 volts. If you have 12-gauge wires with 20 amps, multiply 20 amps by 120 volts to get the total amount of watts that a particular circuit can handle. In this case its would be 2,400 watts. Do this for every circuit to find the total wattage your breaker box needs to handle.
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Check every light fixture and outlet in your home or building. Add up the amps based on wiring.
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As long as you do not have more than 200 amps going into your breaker box you should be fine, but remember that your total watt load will be the sum you determined in Step 3.