Free UK tool
Smart Thermostat Savings Calculator
Manufacturers love quoting big percentages. This works it out from your actual heating spend and only the changes you'd genuinely make — then tells you how long a Nest, Hive or tado° setup takes to pay for itself.
A smart thermostat saves nothing on its own. Every pound comes from a behaviour it enforces: a tighter schedule, a degree lower, heating off when nobody's home. Tick the ones that apply to your household and the numbers stay honest.
Your home
Changes you'd actually make
Savings percentages are published industry and Energy Saving Trust style estimates, combined with diminishing returns and capped at 31% — not our own measurements.
Your verdict
Strong case
Pays for itself in under two years and keeps saving after that.
£155
saved per year
17%
off your heating bill
1.3 yr
to break even
£1,348
net gain over 10 years
That's roughly 2,419 kWh of gas a year at the rate you entered.
How the maths works
Each change carries its own published saving estimate, applied to your heating spend rather than your whole energy bill. Because the measures overlap — turning the thermostat down and running a tighter schedule save some of the same gas — they're combined multiplicatively rather than added, and the total is capped at 31%, which is about the realistic ceiling for heating controls alone in a UK home.
Payback is simply the kit cost divided by the annual saving. If your heating is already on a sensible schedule and the house is occupied all day, expect a modest result — that's the honest answer, and it's why I'd rather show it than quote a headline percentage.
Common questions
How much does a smart thermostat actually save in the UK?
Realistically 8–25% of heating spend, depending on how badly controlled the heating is today. A home already running a tight schedule saves far less than one leaving the boiler on all day.
Do smart radiator valves add much on top?
They help most in homes with rooms that sit unused — a spare bedroom or dining room heated for no reason. In a small flat where every room is used, the extra saving over a good thermostat schedule is small.
Is it worth paying for professional installation?
If you're replacing a wireless receiver wired to the boiler, yes — that's mains work. Many models offer a plug-in or battery option that swaps directly onto an existing wall plate, which most people can fit themselves. Include whichever applies in the cost field above.