Should You Fix Your Energy Tariff?

The Ofgem energy price cap limits the unit rates and standing charges suppliers can charge households on default and standard variable tariffs. It does not cap your total bill. Your annual cost still depends mainly on how much electricity and gas you use.

In practice, the cap moves every quarter. Ofgem reviews wholesale energy costs and other supplier costs, then sets a new cap level for the next period. That means households on a variable tariff are not locked into one price for the year. Their rate can rise or fall at each quarterly reset.

That is where forecasts matter. If analysts expect the cap to rise later in the year, a fixed tariff can be attractive even when it looks only slightly cheaper today. If the market expects the cap to ease, staying variable can make more sense. Neither route is risk-free. A fixed tariff gives price certainty but can leave you paying more if rates fall. Following the cap keeps flexibility but exposes you to future increases.

This calculator uses the current confirmed cap for today's baseline and a blended 12-month forecast for the forward view. That approach is intentionally practical. Most households care about the likely total over the coming year rather than one headline unit rate on one specific date.

We also keep the tone cautious. Wholesale markets can shift quickly, and published forecasts are just that: forecasts. They are still useful because they help frame the trade-off between certainty and flexibility, but they should not be mistaken for guarantees.

Fixing usually makes more sense when the offered tariff is clearly below the blended forecast, especially for medium or high-usage households. Small differences in unit rate add up faster when you use more energy, so a modest-looking rate advantage can turn into a meaningful annual saving.

Certainty also has value. Some households prefer knowing roughly what they will pay over the next year rather than watching each Ofgem announcement. If you are budgeting carefully or you simply dislike surprises, a borderline financial case may still be enough to justify fixing.

Staying variable can make more sense if forecasts are weak, your offered fix is only marginally different, or you expect cap rates to soften. That is particularly relevant if the tariff includes exit fees and you would want the flexibility to move again soon.

The practical question is not whether fixed tariffs are always better or worse. It is whether this specific offer is attractive for your usage, at this point in the cap cycle, with your own tolerance for uncertainty. That is the narrow question this tool is built to answer.

The model is deliberately simple. First, we estimate your annual cost on the current cap using your electricity and gas usage, plus the current standing charges. Second, we create a blended forecast for the next 12 months by averaging the expected cap unit rates across the coming four quarters.

Third, we calculate what your offered fixed tariff would cost using the same usage assumptions and standing charges. We then compare the fixed result against the blended cap forecast. If the difference is large enough, the verdict shifts toward fixing. If the gap is tiny, we mark it as borderline because forecast error could easily outweigh the headline saving.

We also apply a confidence modifier. Even when the maths points in one direction, lower-confidence forecasts call for a more cautious interpretation. That is why the tool explains the likely outcome in plain language rather than presenting it as certainty.

This is a planning tool, not a guarantee. It assumes your usage stays broadly similar, that standing charges are unchanged for comparison purposes, and that published forecasts are directionally useful. The next announcement could still change the picture.