Thermostat Turn-Down Calculator
See exactly what turning your thermostat down by half a degree to two degrees saves on your annual heating bill.
Estimate only. Estimates based on the heating gas use, gas rate and percentage you enter — actual savings depend on your home's insulation, boiler efficiency and how you heat it. Not medical advice — speak to your GP about a safe home temperature if you have a health condition. Source: Energy Saving Trust, NHS.
New thermostat setting: 19°C. New annual heating cost: £558.00.
Saving by turn-down amount
| Turn down | New setting | Annual saving |
|---|---|---|
| 0.5°C | 19.5°C | £31.00 |
| 1°C | 19°C | £62.00 |
| 1.5°C | 18.5°C | £93.00 |
| 2°C | 18°C | £124.00 |
Combined total saving
Turn down by 1°C and cut heating hours and your annual heating cost drops from £620.00 to £558.00.
Staying warm for less
- Heat the human, not the home — a jumper, blanket or hot water bottle often solves the chill more cheaply than another degree on the thermostat.
- Thermostatic radiator valves (TRVs) let you heat living rooms fully while turning bedrooms and spare rooms down separately, room by room.
- A timer that heats only when you're in and awake beats leaving the heating on low all day — modern boilers respond quickly, so "always on" rarely saves money.
Why one degree makes such a difference
Heating a home to a lower temperature reduces the rate at which heat escapes through walls, windows and the roof, so the boiler has to work less to replace it — Energy Saving Trust's long-standing estimate is around 6-13% less heating energy for every 1°C you turn the thermostat down, commonly rounded to about 10%. Applied across a typical UK home's annual heating-only gas use, that adds up to a meaningful saving for a change most people don't even notice day to day. The NHS recommends not letting a home's temperature fall below 18°C where anyone elderly, very young or living with a health condition is present, so this calculator flags any turn-down that would cross that line.