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.
Enter your heating details
Add your annual heating gas use, gas rate and current thermostat setting to see your saving.
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.