Fixed tariffs lock your unit rate and often the standing charge for a set period, so your bills are more predictable. Variable tariffs can go up or down when your supplier changes its prices; default variable tariffs are limited by the Ofgem price cap. This tool explains the pros and cons and lets you enter sample rates and usage for scenario-based cost estimates. We do not imply guaranteed savings—actual bills depend on your usage and the offers available when you compare.
Fixed vs variable tariffs
See pros and cons of each tariff type and optional scenario-based cost estimates. Enter your household energy use and sample rates (from your bill or a comparison). Savings are not guaranteed.
| Type | Pros | Cons |
|---|---|---|
| Fixed | Predictable bills; rate locked for the term; protects from price rises. | May miss price falls; exit fees may apply; can be above or below the cap. |
| Variable | Can benefit when prices fall; often no exit fee; rate follows price cap for default tariffs. | Rates can go up when cap or supplier changes; less certainty. |
Frequently asked questions
- What is a fixed tariff?
- A fixed tariff fixes your unit rate (and often the standing charge) for the length of the contract, e.g. 12 or 24 months. Your bill can still change if your usage changes, but the rate per unit does not. Some fixed deals have exit fees if you leave early.
- What is a price cap and how does it affect me?
- The price cap is set by Ofgem and limits the unit rate and standing charge that suppliers can charge for default and standard variable tariffs. It is updated every three months. If you are on a variable tariff that follows the cap, your rate will be capped; if you are on a fixed deal, the cap does not apply during the fix.
- Can I switch from fixed to variable later?
- Yes. When your fixed term ends, you will usually be moved onto your supplier’s standard variable tariff unless you switch or agree a new fix. You can also choose to switch to another supplier’s variable or fixed tariff. Check for exit fees if you leave a fixed deal early.
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