Estimating my electricity bill - breaking it down

[Anchundan]

I'm trying to work out why my electricity bills are so expensive every month. They seem to be far higher than the neighbours bills.

So I've made a list of all my electric appliances, with the intention of estimating how many hours a day I use them, and how many watts of power they consume.

What's confusing me at the moment, is many of these things have the following :

input : 100-240V 0.3A
output : 7.5V 1.3A

I believe Watts is Volts x Amps - but am I calculating the imput or the output to calculate how much I consume?

i.e. would this particular appliance be 220v x 0.3A = 66W
or would it be 7.5v x 1.3A = 9.75W?

 

[Anchundan]

I think I might buy one of these plug-in energy monitors when next in UK. I'd love to see if things really consume what they say they consume, and also how much power is wasted when things are in 'standby' mode.

I'm currently paying about £50 per month, but already I can see the big consumers are my PC, the TV, and the air conditioning. PC's on all day as I work from home, TV's on all day when my GF's mother stays with us. A/C's only on in the summer, but never realised how much they consume.

 

[Anchundan]

at OP, do you leave your PC a lot ? Mine used to be on 24/7 but now it's just on when needed so that has made a bit of an impact

I don't leave my PC on when I'm not using it, unless I'm defragging, or virus checking, or encoding stuff. I'm litterally staring at it from 9am to 6pm or later (even when taking breaks from work).

Actually, I know the PSU's rated at 480W, but not too sure how much I use of that on average, maybe about 60%.

My water's solar heated (big solar panels on the roof) - it gets piping hot in summer, at about 80°C. It's only in winter that it only gets to about 20°C, so I need to top it up by plugging it into the mains for an hour or two (37°C is the ideal temperature for me!)

I also don't know how much electricity costs per unit out here, I'll need to find out.

How much is it per unit in UK on average?