How to calculate the amperage of an electrical appliance.

Most electrical appliances manufacturers don’t state the amperage of an electrical appliance on their products as I think they are not required by law to do so. However, they are required to state the voltage and  wattage. That being said, knowing the value of the voltage and the wattage, you can easily calculate amperage.


Voltage or volts in short stands for the the electrical charge coming into our homes. Initialized by the letter “V”, the standard voltage in all Malaysian home and in countries that follows the British Standard, is 240 V. +/- 10%. That means it will be perfectly okay if the Voltage in your house is 220 V. It never exceeds 240 unless there is a leakage somewhere. Countries following the US standard have an incoming Voltage of 110V. It’s very much safer as, 240 Volts going through your body might kill you. 110V is a lot milder. The disadvantage is power consumption will be higher with a lower Voltage. I will explain this later.


Watts stands for the amount of current that the apparatus is consuming. It is represented by the letter “W”. So the higher the wattage, the more current it will use up. When purchasing a water heater of a kettle, pay attention to the Watts stated on the label. If you don’t intend to spend too much on your electrical bill, don’t buy one that has a high wattage. On the other hand, if you just boil a kettle of water each day, a higher wattage kettle will boil faster.


Or Amps in short, means the resistance in the appliances. Taking a simple light bulb as an example, when current(V) passes through the filaments, the filament is like a trap, trying to hold back the current from passing through. But the current is strong, it forces itself through so much so that the force causes so much heat that the filament heats up and starts glowing. Now the bigger the trap (W) meaning the filament, the more harder the current will have to push. The harder it pushes, the hotter and brighter it becomes. So that’s why a 100w light bulb will be much brighter than a 40 watts one and very much hotter too.

This resistant force which is trying to hold back the current is measured in Amps. So the higher the amps means the more current it will be using against the force. 240V is sufficient to push through any resistance in any appliances in our home as all electrical items are designed with this spec in mind. We need to know the amperage of electrical items in our house so we can ensure we don’t overload the permitted level. For a normal terraced house with one air condition unit, the permitted level is 30 amps. This means, all your electrical items running together should not exceed this level or you are going to blow a fuse at the Mains.

How To Calculate Amperage

To calculate how many amps a particular item is consuming, Divide Watts with Volts.

W * V= Amps. For example, if your kettle is 2000 watts, divide that by the Volts which is 240 you will know that the kettle is consuming about 8.3 amps each time you use it. Check every item that you are using so that it does not exceed 30 amps altogether. If it does exceeds the permitted level, use your items alternatively. Like if you are cooking a pot of rice, don’t boil the kettle of water first.

Coming back to the safer version of 110V that we don’t fine here, If you divide 2000 by 110 you will be getting a whooping 18 amps or more. So you see, though it’s safer, the consumption goes very much higher.

Reading The Amperage With An Amperage Meter

amp meter

If calculations are not your strong field, you can always get yourself a amp meter. This device reads the amount of amps the appliance is consuming simply by clamping the device around the LIVE feed of the electrical appliances you want to read. This, however requires some skill and knowledge and not for the layman.