Electricity Cost Calculator

In 2026, a homeowner staring at a $487 PG&E summer bill needs to know which appliance to unplug first — the EV charger, the central AC, or the pool pump. Time-of-Use rates (CPUC E-TOU-C, Ofgem Agile, Eurostat dynamic) have made the answer non-obvious because the same kWh costs $0.20 at 02:00 and $0.50 at 17:00. This calculator exists to expose the per-appliance line items the printed bill never shows.

The history of electricity billing starts on 4 September 1882, when Thomas Edison threw the switch on the Pearl Street Station in Lower Manhattan and began metering 85 customers at $0.24 per kWh (about $7.20 in 2026 dollars). The original Edison meter used a chemistry-based zinc-deposition principle — current flow electroplated zinc onto a target electrode and the mass gain was weighed monthly. Inductive electromechanical Ferraris-disc meters (Galileo Ferraris, 1885; commercialized by Westinghouse 1888) replaced the chemistry approach by 1900 and dominated for almost a century.

Time-of-Use tariffs are older than most people realize. The first TOU schedule was filed by the London Electricity Supply Corporation in 1894 for industrial customers; residential TOU appeared in the UK in 1978 (Economy 7), in France in 1965 (Heures Creuses), and broadly in California after the 2001 energy crisis. The FERC has jurisdiction over interstate wholesale rates while state public utility commissions (CPUC in California, PSC in New York) set retail residential rates — which is why the tool ships separate California, Hawaii and US-average presets.

Smart meters (AMI — Advanced Metering Infrastructure) rolled out in the US after the 2009 American Recovery and Reinvestment Act funded $4.5B in grid modernization. By 2024, 75% of US residential meters were two-way digital, enabling 15-minute interval billing and the granular TOU rates this calculator models. The Itron OpenWay and Landis+Gyr Gridstream platforms each push billions of meter reads per day through utility headend systems. The UK SMETS2 rollout reached 80% by 2026 enabling Octopus Energy's 30-minute Agile pricing.

On the tariff side, the regulatory framework comes from the Federal Energy Regulatory Commission (FERC, established 1977 as successor to the Federal Power Commission), the Energy Information Administration (EIA, which publishes Table 5.6.A monthly with state-by-state retail rates), and at the international level the IEC TC 13 family of metering standards (IEC 62052, IEC 62053). The Hawaii preset reflects the structural reality that every kWh on Oahu is generated from imported diesel through HECO's Kahe and Waiau plants — there is no continental grid interconnection.

The big bill-shock moment of 2022-2024 was the European energy crisis. After the Russian invasion of Ukraine cut natural-gas supply, wholesale prices in Germany and the Netherlands briefly hit €700/MWh (versus normal €50/MWh). Retail tariffs lagged but the EU average jumped from €0.21/kWh in 2021 to €0.28/kWh by 2024 — exactly the figure embedded in the tool's EU preset. Ofgem instituted the quarterly price cap mechanism in the UK in October 2022 to smooth the hit to consumers.

By 2026, the leading edge of utility billing is real-time pricing and demand response. CPUC's rule 21 paired with Auto-DR programs lets utilities curtail EV chargers, water heaters, and HVAC during 4-9pm peak in exchange for a kWh discount. Dynamic Operating Envelopes (DOEs), pioneered in South Australia and adopted in California via the IEEE 1547-2018 interconnection standard, modulate residential exports based on local feeder capacity. This calculator's TOU peak/shoulder/off model is a deliberate simplification of that emerging dynamic-rate reality — it captures 90% of the financial signal without requiring a 15-minute API feed.