Smart Plug vs Smart Meter: Whole-Home vs Per-Appliance, and Why You Might Want Both

A smart meter measures your whole home's electricity use and reports it to your supplier for billing; a smart plug measures and controls one plug-in appliance. The smart meter's in-home display tells you how much you are using overall, right now and over time. A smart plug tells you what a specific appliance uses and lets you switch it off or schedule it. They answer different questions, so they work best together: the meter shows that something is using a lot, and the plug helps you find out what and do something about it.

What a smart meter does

In Great Britain, a smart meter replaces your old electricity (and gas) meter. Current-generation meters (SMETS2) send readings to your supplier automatically, which should mean fewer estimated bills and no need to send meter readings yourself.

They usually come with an in-home display (IHD), a small screen you keep in the kitchen or living room. According to Smart Energy GB, the display shows your consumption in kWh and in pounds and pence, daily, weekly and monthly use, and historic use over a rolling 13-month period; on prepay, it can also show your credit balance and low-credit alerts. It shows use in near-real time (Smart Energy GB).

What it does not do is label your appliances. Smart Energy GB suggests using the display to work out which appliances, such as your kettle, use the most energy, which means watching the whole-home figure change as you switch things on. Some supplier apps add estimated breakdowns by appliance type; treat those as estimates rather than measurements.

In the EU, smart meter rollouts differ a lot between countries. Whether you get a display, a supplier app, a web portal or nothing at all depends on where you live and who supplies you.

What a smart plug does

A smart plug with energy monitoring sits between a socket and one appliance (or one extension lead). It measures live watts and the kWh used over time, sends the data to an app, and can switch the socket on or off remotely, on a schedule or with a timer. Our guide to smart plug energy monitoring covers what the readings mean and how accurate they are.

It cannot see anything not plugged into it: not your electric shower, oven, hob, immersion heater, ceiling lights, or the appliance in the next socket. It is also not a billing meter.

Side-by-side comparison

When each one is the right tool

Use your smart meter display when you want to:

• Know your total daily use and cost.
• See your baseload: what the home draws in the middle of the night when nothing obvious is on.
• Check hard-wired appliances, such as how much a shower or an evening of oven cooking adds.
• Track whether your overall use is going down month on month.

Use a smart plug when you want to:

• Know exactly what one plug-in appliance costs per day, week or year.
• Find which device in a group (TV corner, desk, kitchen counter) is drawing standby power.
• Schedule or automatically switch off an appliance that wastes hours.
• Compare two settings or programmes on the same appliance.

Which should you get first?

If you live in Great Britain and do not yet have a smart meter, ask your supplier about one first. It costs nothing extra according to Smart Energy GB, it covers every appliance including the hard-wired ones, and the in-home display gives you the big picture straight away: your daily use, your cost, and your overnight baseload.

If you already have a smart meter, or you rent and cannot change the meter, a smart plug is the natural next step. It fills the gap the display leaves: which appliance is responsible, and what to do about it.

If you are in the EU without a smart meter display, a smart plug is often the quickest way to get any real-time energy data at all, but remember it only covers what you plug into it. Your meter readings, taken at the same time each day, still give you the whole-home total.

How to use both together

This is the most effective way to find and fix waste in a home with a smart meter.

1. Read your baseload. Late at night, with everything normally left on still on, note the live figure on your IHD. Multiply the watts by 8.76 to get kWh a year. For example (hypothetical), a 150 W baseload is 150 × 8.76 = 1,314 kWh a year, about £346 at the Ofgem price cap average of 26.32p per kWh for October to December 2026.
2. List what is always on. Fridges, freezers, router, set-top boxes, chargers, anything in standby.
3. Measure the suspects with a smart plug. One at a time, or one group at a time, for at least a day; a week for fridges and freezers.
4. Account for the gap. Add up what you measured. If it falls well short of your baseload, something unmeasured is drawing power: a hard-wired device, a forgotten dehumidifier, an old freezer in the garage.
5. Act on the biggest items. Schedule, switch off, change settings, or replace.
6. Check the IHD again. Your baseload should drop by roughly what you removed.

Our step-by-step guide to measuring appliance energy use explains how to test hard-wired appliances with the meter.

Common mistakes and myths

• "My smart meter will save me money." Like a smart plug, it only helps if you use the information. The display shows where you are; you still have to change something.
• "A smart plug measures my whole house." It measures one socket.
• "The app's appliance breakdown is exact." Breakdowns built from whole-home data are estimates. Measure the appliances that matter.
• Ignoring the standing charge. Your bill includes a fixed daily charge (54.83p per day for electricity under the October to December 2026 Ofgem cap average). No device changes that; see our UK bill guide.
• Leaving the IHD in a drawer. It works best where you will glance at it every day.

Where Wattly fits (and where it doesn't)

The Wattly smart plug is the per-appliance half of this pairing. It shows live watts, cost per hour, day, week and month, and usage history in the Tuya Smart app, and lets you act on what you find with schedules, timers and remote on/off. It comes in a UK Type G version rated 13 A and EU Schuko versions rated 16 A or 20 A, and needs no hub.

It is not a meter, it cannot see hard-wired appliances, and it will not tell you your whole-home use. If you have a smart meter display, use that for the big picture and a plug like Wattly for the detail.

Related reading

• What uses the most electricity at home
• Standby power explained
• Do smart plugs save money?
• How to save electricity at home in Europe