Energy tariff unit-cost comparator
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Energy bills combine unit rates (pence per kWh) and standing charges (pence per day). Enter your annual electricity and gas usage plus the rates for two tariffs to see which costs less over a year — useful when comparing a price-capped default tariff against a fixed deal.
Tariff A
Tariff B
- Tariff A — annual cost
- £1,708
- Tariff B — annual cost
- £1,595
- Cheaper tariff (Tariff B)
- £113/yr
| Tariff A — electricity | £880.87 |
|---|---|
| Tariff A — gas | £827.61 |
| Tariff B — electricity | £809.05 |
| Tariff B — gas | £786.18 |
| Annual difference (A minus B) | +£113 |
Ofgem caps unit rates and standing charges on default tariffs — not your total bill. Low users can pay more on a low unit rate with a high standing charge; high users usually benefit more from a lower unit rate. Enter figures from your bill or the supplier's tariff information label. Exit fees, warm-home discounts and payment-method discounts are not included.
How it works
- We multiply your annual kWh by each fuel's unit rate and add 365 days of standing charges.
- Electricity and gas are calculated separately, then summed for each tariff.
- The difference shows how much you would save or pay extra per year on Tariff B versus Tariff A.
Common questions
- Where do I find unit rates and standing charges?
- On your bill, annual statement or the supplier's tariff information label. Standing charges are quoted in pence per day; unit rates in pence per kWh.
- Should I switch for a small saving?
- Factor in exit fees, the hassle of meter readings and whether a fixed deal protects you if prices rise. A £30–£50 annual saving may not justify switching; £100+ often does.
- Does this include the Warm Home Discount or direct-debit discounts?
- No. This compares headline tariff rates only. Payment-method discounts and rebates are applied separately on your bill.