You need to know watts and amps to get volts..

http://www.supercircuits.com/resourc...amps-converter
**Science Concept: Volts, Watts, and Amps**
Electricity is measured in terms of amperage, voltage, and wattage.

**Amperage** (

**amps** for short) is a measure of the AMOUNT of electricity used.

**Voltage** (

**volts**) measures the pressure, or FORCE, of electricity. The amps multiplied by the volts gives you the

**wattage **(

**watts**), a measure of the WORK that electricity does per second.

Think of it this way: Electricity flowing through a wire is like water flowing through a garden hose. The amount of water that can fit through the hose depends on the diameter of the hose (amps). The pressure of the water depends on how far open the faucet is (volts). The amount of work that can be done (watts) depends on both the amount and the pressure of the water (volts x amps = watts).