An electricity bill has three moving parts: kWh used, the unit rate per kWh and a daily standing charge. The default here, 125 kWh over a 91-day quarter on a standard variable tariff at 24.5p per kWh with a 61.6p daily standing charge, comes out to about £91.25 before VAT, then £95.81 after the 5 percent VAT applied to domestic electricity. That sits below the typical UK quarterly bill because most homes use considerably more than 125 kWh in three months.

The estimator accepts either a pair of meter readings (subtracting the previous from the current) or a total kWh figure if you already know it. Reading your own meter and entering both numbers gives the most honest result and protects against estimated bills that creep ahead of actual usage. A typical three-bedroom UK home uses roughly 2,700 kWh a year, or about 675 kWh per quarter.

On a standard variable tariff, the rate moves with the Ofgem price cap, currently sitting around 24.5p per kWh in 2026. Fixed tariffs lock the rate for 12 to 24 months; useful when you expect prices to rise, painful when they fall. Economy 7 splits the day into a cheap night rate (often around 15p per kWh) and a more expensive day rate (around 28p), which only saves money if you genuinely shift more than 30 to 40 percent of usage to the small-hours window.

Heat pump owners and EV drivers with off-peak charging are the obvious Economy 7 winners. For a household that mostly uses electricity from 6pm to 10pm, the night rate barely gets a look in and the higher day rate makes the bill worse, not better. The comparison panel in this tool lets you sense-check that before committing to a switch.