Octopus Go vs Octopus 18M Fixed September 2026 v1

Side-by-side comparison of Octopus Octopus Go and Octopus Octopus 18M Fixed September 2026 v1 using real UK smart-meter data.

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The figures above use a modelled household. Your own saving depends on when you use electricity — 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
Octopus

Octopus Go

Time of Use
Full details & per-region rates
Octopus
Octopus

Octopus 18M Fixed September 2026 v1

Standard Fixed
Full details & per-region rates

Questions

We are still calculating the worked example for this comparison. The page refreshes nightly and will show a side-by-side cost once a full period of data has been modelled. The right tariff depends on usage pattern - shift workable load (EV charging, heat pump cycles, hot water) into the cheaper periods of each tariff to maximise the saving.

Octopus Go is a time of use tariff and Octopus 18M Fixed September 2026 v1 is a standard tariff, both from Octopus. 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.

Octopus publishes per-region rates for both these tariffs across the 14 UK DNO areas. Click through 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.

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