By the Numbers
By the Numbers: Ofgem's Next Price Cap Update (27 May 2026) — What a 10% Change Would Mean
Ofgem will publish the next default tariff price cap by 27 May 2026. We model simple +10% and -10% bill scenarios and show how to run your own usage-based estimate.
Ofgem says the next energy price cap levels (covering 1 July 2026 to 30 September 2026) will be published by 27 May 2026, and many households will want the same thing: a quick way to translate “cap changes” into what it could mean for their own bill. Source: Ofgem’s price cap unit rates and standing charges guidance and its cap change notice for 1 April to 30 June 2026.
This article does not try to predict what the cap will do. Instead, it shows a simple “By the Numbers” approach: model a 10% up / 10% down scenario so you can see the scale in pounds and pence, then plug your own usage and tariff details into the UK energy bill calculator.
It is an estimate, not personal financial advice.
The story number
The key dates and period to know:
- Next cap publication: by 27 May 2026 (Ofgem)
- Cap period: 1 July 2026 to 30 September 2026
The price cap is published as unit rates and standing charges (and varies by region, meter type, and payment method). That is why it helps to model scenarios rather than relying on a single “typical bill” figure.
The number to run
If you already know your current annual energy cost (or your latest monthly direct debit), the simplest scenario model is just a percentage change:
- New cost = current cost × (1 + percentage change)
- Change in £ = current cost × percentage change
For example:
- +10% means multiply by 1.10
- -10% means multiply by 0.90
You can run this quickly with the percentage increase calculator.
Run the numbers (simple bill example)
Assume a household currently spends £1,800 per year on energy (example only).
| Scenario | Annual cost (£) | Monthly equivalent (£/month) | Change vs today |
|---|---|---|---|
| Today (example baseline) | 1,800 | 150 | — |
| +10% scenario | 1,980 | 165 | +£180/year (+£15/month) |
| -10% scenario | 1,620 | 135 | -£180/year (-£15/month) |
What this means:
- A “10%” headline can sound abstract, but for a £1,800/year household it is about £15 per month.
- If your baseline is higher (larger home, higher usage), the same percentage change turns into more pounds per month.
Run the numbers with usage (kWh example)
If you want a more “mechanics” view, start from your annual usage:
- Electricity usage (kWh/year)
- Gas usage (kWh/year)
- Electricity unit rate (p/kWh) and standing charge (p/day)
- Gas unit rate (p/kWh) and standing charge (p/day)
Then compare scenarios where unit rates and/or standing charges change.
Here is a worked example using rounded numbers purely to show the calculation pattern (these are not Ofgem cap rates):
- Electricity usage: 2,900 kWh/year
- Gas usage: 12,000 kWh/year
- Example electricity unit rate: 25p/kWh
- Example gas unit rate: 6p/kWh
- Example standing charges: 60p/day electricity and 30p/day gas
That implies an estimated annual cost of about:
| Scenario | Electricity (£/year) | Gas (£/year) | Standing charges (£/year) | Total (£/year) |
|---|---|---|---|---|
| Example baseline | 725 | 720 | 328.50 | 1,773.50 |
| +10% unit-rate scenario (standing charges unchanged) | 797.50 | 792 | 328.50 | 1,918.00 |
This example shows an important point: even if unit rates move, standing charges can be a meaningful slice of the bill, so your total change may not be exactly the same percentage as the unit-rate change.
What the result means
Two households can see different outcomes from the same cap update because:
- Usage varies (home size, insulation, occupancy, heating patterns).
- Cap rates vary by region, meter type, and payment method.
- The cap is expressed as unit rates and standing charges, not a single fixed “bill”.
That is why scenario modelling is useful: it turns “cap talk” into pounds-per-month for your own numbers.
Try your own numbers
1) If you know your current monthly or annual spend:
- Use the percentage increase calculator to test +10% and -10% scenarios.
2) If you want to model based on usage and tariff inputs:
- Use the UK energy bill calculator with:
- your annual kWh usage (from your bill or account)
- your electricity and gas unit rates
- your standing charges
- Then copy the unit rates/standing charges and adjust them by a scenario percentage (for example +10%) to see the new total.
If you are comparing two tariffs (for example, a fixed tariff vs a variable capped tariff), use:
Caveats and source notes
- The Ofgem cap is a maximum for default tariffs; it does not automatically set your exact bill.
- The cap varies by region, payment method, and meter type, so “typical” figures can mislead.
- This article does not forecast or recommend switching decisions. It shows the maths so you can plan.
Sources: Ofgem energy price cap guidance and cap update notes, including the stated publication timeline for the 1 July to 30 September 2026 period.
Reader questions
Does a 10% cap change mean my bill changes by 10%?
Not necessarily. Your bill depends on usage, and the cap is defined via unit rates and standing charges. If standing charges change less than unit rates (or vice versa), the total may move differently.
What numbers do I need from my bill?
For the best estimate, collect:
- Your annual kWh usage for electricity and gas
- Your current unit rates (p/kWh)
- Your standing charges (p/day)
Is this advice on what I should do before the announcement?
No. It is a calculator-led way to translate a potential percentage change into pounds and pence. For decisions, consider your own tariff terms and circumstances.
