Cosy Octopus Variable vs Cosy Octopus 12M Fixed March 2026 v2
Side-by-side comparison of Octopus Cosy Octopus Variable and Octopus Cosy Octopus 12M Fixed March 2026 v2 using real UK smart-meter data.
This comparison is being calculated.
Refreshes nightly — check back tomorrow for the full worked example,
including cost breakdown and monthly chart. Tariff details below are live.
About these tariffs
Octopus
Cosy Octopus Variable
Time of Use
Octopus
Cosy Octopus 12M Fixed March 2026 v2
Time of Use Fixed
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.
Cosy Octopus Variable is a time of use tariff and Cosy Octopus 12M Fixed March 2026 v2 is a time of use 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.