Co-op 18M Fixed October 2026 v4 vs Sainsburys Fix and Reward Fixed 24m v57

Side-by-side comparison of Octopus Co-op 18M Fixed October 2026 v4 and Eon Next Sainsburys Fix and Reward Fixed 24m v57 using real UK smart-meter data. Modelled over 90 days ( – ).

Octopus
Cheaper option

Octopus Co-op 18M Fixed October 2026 v4

Saves £14.06 over 90 days, around £57/yr annualised, on the modelled household.

Your own saving depends on when you use electricity. See how this is calculated.

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Cost breakdown

  Octopus
Co-op 18M Fixed October 2026 v4
 Eon Next
Sainsburys Fix and Reward Fixed 24m v57
Total cost (90 days) £180.90 £194.96
Daily average £2.01 £2.17
Annualised £734/yr £791/yr
Calculated . Levy adjustment applied to dynamic-tariff slots pre-1 April 2026.

Monthly cost

Each bar is the modelled cost for that calendar month using the modelled household’s actual half-hourly consumption pattern.

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The figures above use a modelled household. Your own saving depends on when you use electricity, so run this comparison against your real half-hourly smart-meter readings to see numbers that match your usage.

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About these tariffs

Octopus

Co-op 18M Fixed October 2026 v4

Standard Fixed Cheaper
Full details & per-region rates
Eon Next

Sainsburys Fix and Reward Fixed 24m v57

Standard Fixed
Full details & per-region rates

Questions

Over the modelled 90-day period, Co-op 18M Fixed October 2026 v4 worked out cheaper than the other tariff by £14.06 for a representative UK home. Annualised that is roughly £57 per year. Your own saving depends on when you use electricity - shift load into cheaper windows on either tariff for a larger gap.

Co-op 18M Fixed October 2026 v4 is a standard tariff from Octopus. Sainsburys Fix and Reward Fixed 24m v57 is a standard tariff from Eon Next. They differ in how the unit rate is structured across the day, which is what drives the cost difference for households with shiftable load.

We take a real UK home's half-hourly smart meter data over the previous 90 days and model the bill on each tariff using the supplier's current published rates and standing charges. Standing charges scale with the modelled period; unit rates apply per half-hour using each tariff's rate structure (standard, Economy 7, time-of-use bands, or wholesale-tracking). Full methodology and data sources are linked below.

Both Octopus and Eon Next publish per-region rates across the 14 UK DNO areas. Go to either tariff page below to see the rates and standing charge specific to your DNO. Some tariffs require a smart meter or have other eligibility criteria set by the supplier.

New customers signing up via the link on this page may receive a £50 credit. Bonus eligibility is determined by Octopus at switch confirmation. We earn a small commission when a switch completes - this helps fund the site and does not affect your price.

The cost calculation rebuilds every night using current rates. Page caching is one hour so repeat visits within the day are fast. If a tariff's rates change mid-day, you will see the new numbers on the next nightly refresh.

How this comparison is built. Every cost figure on this page comes from modelling real half-hourly UK smart-meter data against each supplier’s current published rates and standing charges. The calculation refreshes nightly. We earn a small commission when a switch completes via a referral link. It does not affect the price you pay.

Read the full methodology Where the data comes from