UK Economy 7 Calculator
Compare a standard electricity tariff against an Economy 7 day/night tariff using your own usage and rates.
Independent UK energy information from PowerGuardian.
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Figures reviewed June 2026 and updated monthly where appropriate. All results are estimates.
Annual daytime usage in kWh.
Annual night-time usage in kWh.
Pence per kWh.
Pence per kWh.
Pence per kWh.
Any annual standing charge difference in pounds. Leave as 0 if unknown.
Enter all unit rates in pence per kWh and the standing charge difference in pounds per year. This tool provides an estimate, not a guaranteed bill amount, and Economy 7 does not always save money.
Enter your day usage, night usage and tariff rates to compare Economy 7 with a standard tariff.
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How the Economy 7 Calculator Works
The calculator compares the cost of a single standard electricity rate against separate Economy 7 day and night rates. It applies your standard rate to your total usage, then applies the Economy 7 day and night rates to your day and night usage separately, adds any standing charge difference, and shows the estimated annual saving or extra cost.
What Is Economy 7?
Economy 7 is a two-rate electricity tariff that gives you cheaper electricity during seven off-peak night-time hours, usually in exchange for a higher daytime rate. The exact off-peak window depends on your supplier and meter.
When Does Economy 7 Make Sense?
Economy 7 usually works best for households that can shift a meaningful share of their electricity use to the off-peak hours — for example running storage heaters, charging an EV or using appliances overnight. If most of your usage falls in the daytime, the higher day rate can outweigh the cheaper nights.
Why Economy 7 Can Be Confusing
Economy 7 can be hard to judge because suppliers use different off-peak time windows, rates vary by region, and the benefit depends heavily on equipment like storage heaters, immersion heaters and EV charging. Many households are also unsure exactly how much of their usage actually happens at night.
What Night Usage Percentage Do You Need?
The calculator estimates the break-even point — the share of your usage that would need to fall in the cheaper night period for the savings to outweigh the higher day rate. If your night usage percentage is above the break-even figure, Economy 7 tends to look favourable on your numbers.
Related PowerGuardian Tools
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Check Whether Your Tariff Fits Your Usage
Use PowerGuardian tools and guides to understand whether your current electricity tariff suits how your household actually uses energy.
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