The small screen that arrived with your smart meter, usually a plastic unit that sits on the kitchen worktop, is the most useful energy gadget most people already own and never really use. It is a live readout of what your whole home is spending, updated every few seconds. Used well, it turns the abstract question of where your money goes into something you can watch in real time, walking round the house switching things on and off and seeing the number move. It costs nothing extra, it needs no setting up beyond entering your tariff, and it can pay for a fair few evenings of attention many times over.
The short answer. The in-home display shows your live electricity use, usually as pence per hour or watts, plus running totals for the day, week and month. The most valuable screen is the live cost: switch things on and off and watch it jump, and you quickly learn which appliances are the expensive ones. Set your unit rate and standing charge in the display so the money figures are right, then use it to find and cut your biggest draws. It reads only your whole-home total, so for a single appliance a plug-in monitor is more precise.
What the display is actually telling you
The display talks to your smart meter over a short-range wireless link, so it shows what the meter is recording without you having to go and read it. Most models cycle through a few screens. There is a live now figure, showing how much electricity your home is drawing this instant, given either in watts, in kilowatts, or as a cost in pence per hour. There is a set of running totals for today, this week and this month, in both energy used and money spent. If you have gas through a smart meter too, there is usually a separate set of the same figures for gas, though gas updates far less often, typically about every half hour rather than every few seconds. And there is often a traffic-light indicator, a coloured bar or dot meant to show at a glance whether your current use is low, medium or high.
The single most useful of these is the live now figure shown as a cost. When it reads, say, 8p an hour, that is the rate your home is spending right now if nothing changes. Leave the kettle off and the lights low and it might sit at 3p or 4p an hour, the background hum of the fridge, the router and standby devices. Switch on something that makes heat and it leaps. That responsiveness is the whole point, and it is where the learning happens.
Set your tariff first, or the money is wrong
Before you trust any of the pound-and-pence figures, check that the display knows your actual prices. Many displays pick up the unit rate and standing charge automatically from the supplier, but not all do, and after a price change or a tariff switch the stored rate can be out of date. If the money figures look off, dig into the settings menu and enter your current unit rate in pence per kWh and your daily standing charge, both of which are printed on your bill. The energy figures in kWh are measured by the meter and are always right; it is only the conversion into money that depends on the rate you have told it. Get that rate correct and every cost the display shows becomes trustworthy. If you are unsure what a unit even is, the what is a kWh guide explains it, and the kWh to cost calculator does the conversion by hand.
Hunt down what costs the most
Here is the exercise that makes the display worth its shelf space. Spend ten minutes walking round the house with it in your hand, switching things on one at a time and watching the live figure. Boil the kettle and watch it jump by around 3kW, roughly 78p an hour while it runs, though it only runs a couple of minutes. Turn on the electric shower and it may leap by 8 or 9kW, the biggest single jump in most homes. Switch on the oven, the tumble dryer, the immersion heater, and each one shows its cost as a step up in the number. Then switch on all your lights, or a laptop charger, and notice how little the figure moves. This is the lesson the display teaches better than any article: the things that make heat cost real money, and the things that do not cost almost nothing.
| Switch on... | Rough jump in live use | Cost per hour while running |
|---|---|---|
| Electric shower | ~8.5 kW | ~£2.21 |
| Kettle | ~3 kW | ~78p |
| Tumble dryer | ~2.5 kW | ~65p |
| Oven | ~2 kW | ~52p |
| Fridge-freezer | ~0.1 kW | ~3p |
| LED lights, whole room | ~0.03 kW | ~1p |
Illustrative jumps at an example 26p per kWh. Your own appliances will differ; the display shows your real numbers as you switch each one on. See what uses the most electricity for the full ranking.
Once you have done this once, you carry the knowledge for good. You stop worrying about leaving a phone charger plugged in, because you saw it barely move the number, and you start paying attention to the shower, the dryer and the heating, because you saw those send it soaring. That reallocation of worry, away from the trivial and towards the things that matter, is worth more than any single saving.
Reading the daily and monthly totals
The running totals answer a different question: not what is expensive right now, but whether your habits are adding up to more or less than you expected. Glance at the day total each evening for a week and you build a feel for a normal day, which makes an abnormal one obvious. A day the total is much higher than usual, and you can usually think back to what did it: a load of washing dried indoors on the heater, a long shower, the oven on for a roast. The month figure is the one to check against your bill. If the display says you have spent a certain amount this month and your direct debit assumes far more, that is a signal worth acting on, because it may mean you are building up credit you could reclaim or reduce.
One caution with the totals. The display's month figure counts from a date it chose, not necessarily your billing month, and it may or may not include the daily standing charge, the fixed sum you pay every day regardless of use. Check whether your display adds the standing charge into its totals; if it does not, your real spend is higher than the screen suggests by the standing charge times the number of days. That fixed charge is also why the number is never zero even on a day you use almost nothing.
If you are on a time-of-use tariff
The display earns its keep twice over if your electricity price changes through the day, as it does on Economy 7 or a modern time-of-use tariff. On these, the same appliance costs very different amounts depending on when you run it, and the live cost figure reflects that if the display knows your rates. A dishwasher run at the peak rate might show as costing three or four times what the same cycle costs in the cheap overnight window. Watching that gap on the screen is the clearest possible nudge to move the flexible loads, the dishwasher, the washing machine, the EV charge, the immersion heater, into the cheap hours. Some newer displays even show which price band you are in right now, so you can see at a glance whether it is a good moment to put the washing on.
What the display cannot do
For all its usefulness, the in-home display has real limits worth knowing. It shows your whole-home total, not individual appliances, so when the number reads 0.4kW you know the house is drawing that, but not how it splits between the fridge, the router and whatever else is on. To pin down one appliance precisely, a plug-in energy monitor that sits between the appliance and the socket is the better tool, because it measures only what is plugged into it. The display also cannot see anything hardwired in a way the meter does not separate, and it will not tell you whether an appliance is faulty or simply thirsty. And crucially, the display does not save a single penny on its own; it only shows you where the money goes. The saving comes from what you change once you have seen it. If your display has gone blank or stopped updating, it is worth asking your supplier to help re-pair it, because a working one that you actually glance at is one of the cheapest ways to keep a grip on the bill. To turn any figure you see into a running cost, the appliance running cost calculator finishes the sum.
Common questions
How do I use my smart meter in-home display to save money?
Set your correct unit rate and standing charge in the display, then walk round the house switching appliances on and off while watching the live cost figure. You quickly learn which things are expensive, usually anything that makes heat, and can focus your effort there. The display shows where the money goes; the saving comes from what you change.
Why is the cost on my in-home display wrong?
Usually because the stored tariff is out of date. The energy figures in kWh come straight from the meter and are accurate, but the money figures depend on the unit rate and standing charge saved in the display. Enter the current rates from your bill in the settings menu and the costs will line up.
Does the in-home display show gas as well as electricity?
If you have a smart gas meter, most displays show gas use and cost on a separate screen. Gas updates far less often than electricity, typically about every half hour rather than every few seconds, so you will not see it jump in real time the way electricity does.
Does a smart meter display actually reduce my bill?
Not by itself. It is a monitor, not a control, so it saves nothing until you act on what it shows. Its value is making your live and total spending visible, which helps you spot the expensive habits and shift flexible use to cheaper times if you are on a time-of-use tariff.