Reading your smart meter: what the IHD numbers actually tell you
The in-home display shows four numbers that most people cannot quickly interpret. Here is what each one means, and which two are worth watching.
Open the little screen that came free with your smart meter, press the Home button, and you are looking at four numbers: a kilowatt-hour figure, a pound figure, a pence-per-kilowatt-hour figure, and something called a standing charge. If you cannot tell within ten seconds which of those four to act on, you are in the same position as roughly 15 million British households. The in-home display (IHD) is one of the most useful pieces of hardware in a UK home. It is also one of the worst explained.
What follows is the short version. kWh is the one you can act on; standing charge is the one you cannot. The pound figure is a sum of the first two, and the p/kWh is a rate that changes quarterly whether you look at it or not. Four numbers, two levers, one habit.
The kilowatt-hour: the only live number that matters
A kilowatt-hour is the unit of energy you are actually buying. One kWh runs a 1,000-watt kettle for an hour, or a 100-watt bulb for ten hours, or an 8 kW electric shower for seven and a half minutes. On most IHDs the current figure is either in red/amber/green bands or as a rolling wattage reading in the top-right.
The useful trick is to understand your baseline. A typical British semi with the heating off and nothing in particular running sits between 100 and 300 watts: fridge, freezer, broadband router, standby kit, the odd always-on charger. That is your floor. Anything above it is a behaviour you are performing, almost always involving heat.
Turn the electric oven on. Watch the IHD jump by about 2,500 to 3,500 watts. Switch on the kettle. Watch it jump by 2,800. Run the tumble dryer. Jump by 2,400, held for forty minutes. Those three are more than 90 per cent of a kitchen's electric bill between them; nothing else you turn on will change the meter in the way those do.
If an appliance doubles the IHD reading when you switch it on, it is worth watching. If it barely moves the needle, you are spending your attention in the wrong place.
Standing charge: paid every day whether you use anything or not
Standing charge is the daily fixed fee you pay for being connected to the network. In late 2026 the typical figure under the Ofgem price cap sits around 60p/day for electricity and 32p/day for gas — about £335 a year combined, before you have boiled the first kettle.
This is the number you cannot change by switching things off. You can change it only by switching to a tariff with a different standing charge structure, or by disconnecting entirely (rarely sensible). The IHD shows it as a running counter; some displays let you compare today's standing charge against today's usage, which at least makes the ratio visible.
For a very low-usage household — an elderly single person in a small flat using perhaps 1,500 kWh a year of electricity — standing charges can be 40 per cent of the bill. For an average three-bedroom family house they are closer to 15 per cent. If you are in the first category, a no-standing-charge tariff is worth investigating; Citizens Advice's energy pages list current options and the trade-offs. If you are in the second, standing-charge-shopping is a smaller lever than usage-shopping.
Pence per kilowatt-hour: the price cap and your tariff
The p/kWh figure on the IHD is your current unit price. Under the price cap from 1 October 2026 to 31 December 2026, the typical electricity unit rate is around 27 p/kWh; gas is around 6.5 p/kWh. Those figures are set by Ofgem quarterly for direct-debit standard-variable tariffs; fixed-price tariffs lock in a different rate for their term.
The IHD does not know which tariff you are on unless the supplier has pushed the figures to it. About 85 per cent of SMETS2 meters now have current tariff data populated; SMETS1 meters, particularly the older British Gas and SSE kit, often show the installer's placeholder rate from 2017 and have never been updated. If your p/kWh on the IHD does not match the figure on your most recent bill, trust the bill — or ask your supplier to push a tariff refresh to the meter.
Regional variation matters here. The same supplier charges different unit rates in Scottish Hydro Electric region (north Scotland) than in London, driven by network charges. The IHD does not explain this; it just shows the local figure.
The pound figure: a running total, not a budget
The pound figure on the Home screen is today's spend so far: standing charge plus (kWh × unit rate). It is the number that catches attention and the number most people watch wrong.
It catches attention because it is in pounds, and pounds are what we feel. It is wrong to watch because it includes the standing charge — which you have no power to change — and because it is cumulative over the day, which means it always goes up, and always feels like it should not. By 6pm on a cold February evening you can be at £6 on the IHD without having done anything unusual.
The better habit is to look at the figure at the same time two days in a row. Thursday 6pm against Wednesday 6pm. If Thursday is £1 higher despite nothing obvious having changed, something changed — a tumble-dryer load, a longer bath, the heating coming on an hour earlier because it got colder overnight. If it is roughly the same, you are running normally. The absolute pound figure means less than the day-over-day delta.
The two numbers worth a weekly glance
If this is more than you want to think about: look at two numbers, once a week.
First, your weekly kWh total for electricity. Most IHDs will show this under a history or weekly-summary menu. A benchmark: an average UK home uses about 2,700 kWh of electricity a year, which is 52 kWh a week. Allow some seasonality — January is a bit higher than June — and you have a sanity check. If you are at 90 kWh a week in May, something is on that you did not notice.
Second, your weekly kWh total for gas (if you have a dual-fuel setup). The average UK home uses about 11,500 kWh of gas a year, overwhelmingly weighted to the heating months. In July this should be a small number — maybe 5-15 kWh for hot water alone. In January it can be 400 kWh in a cold week. If July is 100 kWh, your boiler is doing something it should not.
The Ofgem typical domestic consumption values page has current benchmarks by household size. Compare yours. If you are above the Ofgem high band without an obvious reason — big house, electric heating, home working all day — the first place to look is your heating programme and hot-water schedule.
What the IHD will not tell you
Three things to be clear about. The IHD does not know which appliance drew which kWh; it only knows total. If you want appliance-level data you need a smart plug for each appliance (Shelly, Tapo and TP-Link do reliable ones under £15) or the appliance itself must report over Wi-Fi.
The IHD does not predict your bill reliably more than a week out. The extrapolated "monthly" figure some displays show assumes current usage holds; in practice usage swings by 50 per cent month to month in a British home with central heating.
And the IHD is not the source of truth for the supplier. The supplier bills from the smart meter itself; the IHD is a read-only copy. If the IHD stops working — usually a flat battery or a Zigbee connection issue — the bill carries on unaffected. You do not need to do anything urgently about a broken IHD, though it is worth asking the supplier for a replacement because the habit is more valuable than the hardware cost.
The point of any of this is modest. Twenty seconds a week looking at two numbers — weekly kWh for each fuel — tells you most of what you need to know. The p/kWh and the standing charge are context; the pound figure is theatre; the kWh is the number. If you only remember one line from this piece: your eye should go to kWh, and your action should go to the three or four heat-based appliances that move it.