UK Energy Price Cap Change Calculator: Percentage Change in Your Bill
Work out the percentage change in the UK energy price cap between two periods — and the annual and monthly pound difference — when Ofgem updates the cap.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Cap change | Annual change |
|---|---|---|
| £1,600 to £1,760 (+10%) | 10.00% | 160 |
| £1,923 to £1,690 (−12.1%, cap fell) | -12.12% | -233 |
| £1,690 to £1,738 (+2.8%) | 2.84% | 48 |
| £1,400 to £1,600 (+14.3%) | 14.29% | 200 |
How This Calculator Works
Enter the previous and new annual price-cap figures (for typical household use) or your own estimated annual bills. The calculator finds the percentage change and the annual difference. Divide the annual change by 12 to see the monthly impact.
The Formula
Percentage Change
Old is the starting value, New is the ending value
Worked Example
An energy price cap rising from £1,600 to £1,760 a year is a 10% increase — £160 more a year (about £13 a month). The Ofgem energy price cap limits the unit rates and standing charges a supplier can charge most domestic customers on a standard variable tariff in England, Scotland, and Wales. It's updated quarterly, and the widely-quoted figure is the annual cost for a household with 'typical' consumption — but the cap is on rates, not a maximum bill, so your actual bill depends on how much energy you use.
Key Insight
The UK energy price cap is frequently misunderstood, and getting it right helps you judge a change. Crucially, the cap is not a limit on your total bill — it caps the unit rates (per kWh for gas and electricity) and the daily standing charges. The headline figure Ofgem and the media quote is the estimated annual cost for a household with 'typical' consumption, so it's a benchmark, not your personal maximum: use more energy and you pay more than the headline; use less and you pay less. The cap is reviewed quarterly, so it moves up and down with wholesale energy costs, and the percentage here shows how steep a given change is. A few practical implications: the cap applies to standard variable tariffs in England, Scotland, and Wales (Northern Ireland has a separate market), so if you're on the cap, a change directly affects your rates; fixed-rate deals sit outside the cap and may be cheaper or pricier than it depending on the market, so when the cap rises it's worth checking whether a fixed deal now beats it; and the standing charge (a daily fixed fee regardless of usage) is part of the cap and has been a point of contention for low-use households. To act on a change: compare your tariff against the new cap and against available fixed deals, and reduce usage where you can (the cap controls rates, but your consumption controls the bill). The percentage and the monthly figure show the impact; whether to switch tariffs depends on comparing your options against the new cap.
Frequently Asked Questions
How is the energy price cap change calculated?
Subtract the old annual figure from the new one, divide by the old figure, and multiply by 100. From £1,600 to £1,760 is (£1,760 − £1,600) / £1,600 = 10%, a £160 annual increase (about £13/month).
Is the price cap a limit on my bill?
No — this is the key misunderstanding. The cap limits the unit rates (per kWh) and daily standing charges, not your total bill. The widely-quoted figure is the estimated annual cost for 'typical' consumption. Use more energy and you pay more than the headline; use less and you pay less — your usage determines the bill.
How often does the cap change?
Ofgem reviews and updates the price cap quarterly, so it moves up or down with wholesale energy costs. That's why bills on the standard variable tariff change through the year. The percentage here shows how big a given quarterly change is for a typical household.
Should I get a fixed deal instead of the cap?
It depends on the market. Fixed-rate tariffs sit outside the cap and can be cheaper or pricier than it. When the cap rises, it's worth checking whether a fixed deal now beats the new cap — a fixed deal gives certainty but you're locked in if the cap later falls. Compare your options against the new cap before deciding.
What about the standing charge?
The standing charge is a daily fixed fee you pay regardless of how much energy you use, and it's part of what the cap sets. It's been contentious for low-use households, who pay it even when consuming little. When comparing the cap or tariffs, factor both the unit rates and the standing charge, not just the headline annual figure.
Related Calculators
Methodology & Review
The change is the difference between the new and old annual figure divided by the old figure, multiplied by 100. The price cap is set on unit rates and standing charges for typical use; a household's actual bill varies with consumption, so this compares the headline cap (or your estimated annual bill) between periods.
Written by Ugo Candido · Last updated May 22, 2026.