The term “V” stands for “volt,” which is a unit of electrical potential. For example, if the load is 10 amps, then the wattage of the 12 volt amp would be 120 watts (12 volts x 10 amps = 120 watts). To calculate the wattage of a 12 volt amp for a particular load, we can use the equation: Watts = Volts x Amps. However, the wattage of a 12 volt amp can vary depending on the electrical load.Īn amp can have a wattage rating ranging from a few watts to thousands of watts. Therefore, a 12 volt amp is equal to 12 watts. How many watts are in a 12 volt amp?Īt a constant voltage of 12 volts, a single ampere is equal to 12 watts. Therefore, 12 volts 120 watts is equal to 10 amps. This can be calculated by using the following formula: Amps = Watts / Volts = 120 / 12 = 10 amps. How many amps is 12 volts 120 watts?ġ2 volts 120 watts is equal to 10 amps. To find the wattage at 12V, multiply the amps (I) by the voltage (V): W (watts) = I (amps) x V (volts).Īn example would be if the amps is 2A then the wattage would be 24W (2A x 12V). An example would be if the wattage is 24W then the amps would be 2A (12V / (24W / 12V)). The equation to use would be I (amps) = 12V / (W / V) or I (amps) = 12V / (W / 12V). In the equation I (amps) = V (volts) / R (ohms), we can substitute the 12 V and the wattage (W) to come up with the amps. Ohm’s law states that the current (I) flowing through a conductor is equal to the voltage (V) divided by the resistance (R). capacitor) and to draw a significant current (and thus need to rate the cables correctly for this current) but to consume no energy (zero watts).To convert 12V watts to amps, you need to use Ohm’s law. As you electrical types know, it is possible to have a voltage across a device (e.g. Power factor is always between zero and 1 because watts (real power) is always less than or equal to volt amperes. This is because the currents for each device are not necessarily in phase with each other.īut – importantly – you can add up the individual VA ratings to get a conservative figure since the actual total (calculated correctly) will always be less than or equal to this value. Unfortunately (apart from direct current circuits) you can’t simply add the VA rating of devices to come up with the total VA rating. You must ensure your wires and associated circuits can cope with 2.2amps (rms). If it is supplied by a 230Vrms ac line you would calculate maximum current as 500 VA/230Vrm = 2.2amps (rms). So to work out the current draw of a device you simply take the VA and divide by rms voltage.įor example, you have a device which is rated at 500VA (maximum VA the device will draw). Volt amps are very important for calculating current draw (and is essential to know in sizing cables). A standard multimeter is not much help here. The measurement of watts does require specialized equipment where both voltage and current needs to be measured over a specific time. When calculating the real power for multiple devices you simply add the watts for each appliance. Rms volts refers to root mean square voltage (which is peak volts divided by square root of 2).įor dc circuits, this simply becomes W = V (dc) x I (dc). Watts are calculated by W = volts (rms) x amps (rms) x cos (phi) where phi is the angle between the current and voltage for ac circuits (cos (phi) is often referred to as the power factor). People building aluminium smelters would consider these numbers as they would make a big difference to a business case. Other interesting ones are Australia (29c/kWh), UK (20c/kWh) and South Africa and Canada (10c/kWh). For example (for 2011 in US cents), in India it is 8c/kWh against Denmark where it is 41c/kWh (perhaps – and I am speculating here – they are paying for the enormous investment in wind energy). We have a surprisingly wide range of charges throughout the world for kilowatt-hour charges. This is what you as a consumer generally pay your electrical utility in kilowatt-hours (a 60W light bulb left on for 10 hours consumes 0.6 kWh). One watt is the consumption or generation of energy at the rate of one joule per second. So herewith a quick summary of the differences with some interesting alternative calculations to work out total VA (I am waiting for the deluge of critiques from my electrical brotherhood).

As you would know, electrical products generally indicate both to show how much energy and current they draw.

Amp v watt