The short answer
For two suitable new appliances, compare purchase price plus annual electricity cost over the same chosen period. Annual electricity cost is compatible annual kWh multiplied by your tariff. This model excludes unentered costs such as repairs, financing and water; the chosen period is not a lifetime forecast.
Compare purchase price plus electricity on one basis
For two new appliances meeting the same need:
Modeled cost = purchase price + annual kWh × price per kWh × chosen years.
This is a useful part of ownership cost. It does not automatically include repairs, installation, water, finance or disposal. The FTC encourages considering energy information alongside purchase price; a lower running cost alone does not settle the buying decision.
Use compatible capacities and energy sources. For a cycle-based appliance, annualize the appropriate task energy with the same planned frequency before comparing prices.
A five-year purchase comparison
Consider two illustrative fridge candidates at an illustrative £0.28/kWh:
| Quantity | A | B |
|---|---|---|
| Purchase price | £550 | £650 |
| Annual energy | 365 kWh | 250 kWh |
| Annual electricity | £102.20 | £70.00 |
| Five-year purchase + electricity | £1,061.00 | £1,000.00 |
B costs £100 more upfront and saves £32.20/year. In this five-year scenario, it costs £61 less overall. These figures are illustrative inputs, not model recommendations, retail prices or national averages.
Enter them in the appliance comparison and replace the energy, prices and tariff with your own shortlist.
Change the period before interpreting payback
| Scenario period | A total | B total | Lower modeled total |
|---|---|---|---|
| 2 years | £754.40 | £790.00 | A by £35.60 |
| 5 years | £1,061.00 | £1,000.00 | B by £61.00 |
| 10 years | £1,572.00 | £1,350.00 | B by £222.00 |
Simple extra-price payback is £100 ÷ £32.20, about 3.1 years. A period shorter than that leaves B’s extra price unrecovered in this electricity-only comparison.
The tool supports chosen periods from 1 to 30 years. Neither its selector nor a payback number predicts service life. These totals assume the appliances remain usable and the entered consumption and tariff persist throughout the period.
Find the electricity price that changes the outcome
When B uses less energy and costs more, the equal-cost tariff for a selected period is:
Extra purchase price ÷ (annual kWh saving × years).
For five years in this example:
£100 ÷ [(365 − 250) × 5] = about £0.174/kWh.
Above that threshold, B has the lower five-year purchase-plus-electricity total on these inputs; below it, A does. At £0.15/kWh, B costs £13.75 more over five years. At £0.40/kWh, B costs £130 less. These rates test assumptions; they are not future-price forecasts.
Use the scenarios tool to explore chosen tariffs and energy assumptions while retaining the same cost boundary.
Keep omitted costs visible
| Component | Treatment in the two-purchase tool |
|---|---|
| Entered purchase price | Included |
| Electricity on the entered energy and tariff basis | Included |
| Delivery, installation and disposal | Not added separately; note any difference outside the result |
| Repairs, finance, water and detergent | Excluded |
| Changed tariffs, discounting and future failure | Not forecast |
An unchanged household fixed fee does not increase the electricity saving between appliances. For two complete tariffs, use the tariff comparison instead.
Choose a keeping baseline for an appliance you already own
If the current appliance works, its past purchase price is already paid. Replacement payback compares keeping with the full net replacement outlay, including entered installation, disposal and confirmed credits.
That is different from comparing a £100 price premium between two new purchases. Read the payback explanation and retain the source, quote date, cost boundary and chosen period with any saved or printed result.