← All guides

The cheapest tariff depends on how you use energy

There’s no single “cheapest tariff” — the best deal depends on when you use energy, not just how much. Here’s why, and how to find yours.

• Fixed tariffs lock your unit rate and standing charge for a set term. Best if your usage is steady and you want certainty — and a good hedge when the price cap is rising.
• Standard variable (the price cap) moves with Ofgem’s cap every quarter. It’s the default, rarely the cheapest, but it carries no exit fee.
• Time-of-use tariffs (Economy 7, EV and “go” tariffs) charge different rates at different times — cheap overnight, dearer at peak. Brilliant if you can shift a lot of use to the cheap window (EV charging, a heat pump, storage heaters), and expensive if you can’t.

So the genuinely cheapest tariff for you is the one priced against your own half-hourly usage — a heavy-overnight home and a 9-to-5 home get different answers from the same list. Most comparisons just use a “typical” profile and miss this entirely.

Joulely models every tariff type — fixed, variable and time-of-use, across gas and electricity — against your real usage, and tells you the genuinely cheapest for your home. Free, and ranked purely on price.