I have a "KILL A WATT" plugged in to one of our outlets at all times. This will not only tell you the voltage, but it will also tell you the frequency, which is important when on generator to see if you have 60 cycles).
If you plug any appliance in to it, it will tell you how many amps that appliance actually draws as well as the wattage.
These are available at many big box stores or online for less than $20 and since they are a digital readout, they are a little easier to use than a voltmeter for some. There are no leads to mess with. You just plug it in.
