Watt Split

The meter gives you one number for everything in the house, which is why the argument about a high bill never gets anywhere. It might be the air conditioner. It might be the water motor, or the second refrigerator nobody switches off, or the six fans that run all day. Nothing on the bill tells you, so the question gets settled by whoever sounds most certain. Watt Split answers it with arithmetic instead. Enter each appliance once with the wattage printed on its plate, and say how many of them there are - six identical fans go in as one row with six against it. Then, as the day goes, tap in roughly how many hours each one ran. Half an hour a tap, or type an exact figure when you know it. From that the app works out the units each appliance accounts for and draws them as a block of tiles, sized in proportion, so the appliance eating your units is simply the biggest shape on the screen. Below the block the same figures are ranked, with each appliance's share, its hours and what a single hour of it comes to in units. The second half of the app is the honest half. Write down the number on your meter dial whenever you pass it, and Watt Split works out what the meter genuinely recorded between one reading and the next. It then puts that real figure against the total your own entries add up to over exactly the same days, and tells you the difference. Where the meter recorded more, those units appear in the block as their own amber tile, to scale, because they are part of what you are paying for even though nothing in your list explains them. Where your entries come out higher than the meter, the app says so plainly and tells you a wattage or an hours figure needs correcting, rather than dressing a mistake up as a saving. It is careful about what it claims. A plate rating is what an appliance draws at full tilt, and a refrigerator or an air conditioner cycles on and off, so the per-appliance figures are estimates for comparing your own appliances against each other - never measurements. The app says this on the screen where the figures appear, not only in the small print. Your meter reading is the one real number it has, and it treats it that way. There is nothing about money anywhere in it. No tariff, no slab, no bill, no estimate of what an appliance costs you. It deals in units and hours, which is what you have to understand before any of the rest makes sense. Everything stays on your phone. There is no account to make, no sign-in, no subscription, and the app never asks for a single permission, because it needs none. It works with the phone in flight mode on the roof beside the meter, and it reads nothing from your electricity supplier, your smart meter or your inverter. You type what you know; it does the arithmetic you would not otherwise do. Set the day of the month your own billing period starts and the split lines up with the bill you actually receive. Step back through earlier periods any time to see what changed. Watt Split is not a measuring device and gives no electrical, wiring or safety advice.