Energy Cost Calculator

About the Energy Cost Calculator

An energy cost calculator determines the annual, monthly, and daily electricity expense from total energy consumption in kWh and your electricity rate — including support for time-of-use (TOU) pricing with separate peak and off-peak rates. For most households and businesses, electricity is the second-largest energy expense after natural gas (or first in all-electric homes), and knowing the exact annual cost from your meter readings enables accurate budgeting, ROI calculations for efficiency upgrades, and comparison of utility rate plans. Our energy cost calculator goes beyond simple flat-rate calculations to model time-of-use tariffs that are increasingly common as smart meter deployment expands globally. TOU pricing rewards customers who shift consumption away from peak demand periods — running dishwashers, EV chargers, and washing machines overnight can cut costs 20-40% on TOU plans. The calculator shows the flat-rate versus TOU cost comparison when TOU inputs are provided, quantifying the potential savings from load shifting. Relevant for residential and commercial electricity customers in the USA, UK (Economy 7/10 tariffs), Canada, Australia (Time of Day rates), and the EU.

How It Works

Flat rate: Annual cost = Annual kWh × rate/kWh. TOU rate: Annual cost = (Peak kWh × peak rate) + (Off-peak kWh × off-peak rate), where Peak kWh = Total kWh × peak fraction. Example 1 (flat rate): 12,000 kWh/year at $0.14/kWh: Annual cost = 12,000 × $0.14 = $1,680/year = $140/month. Example 2 (TOU comparison): 12,000 kWh/year, 40% peak usage, flat rate $0.14. TOU: peak $0.25, off-peak $0.08. TOU cost = (4,800 × $0.25) + (7,200 × $0.08) = $1,200 + $576 = $1,776/year at current peak fraction. If you shift 20% of peak usage to off-peak: 24% peak, 76% off-peak. TOU cost = (2,880 × $0.25) + (9,120 × $0.08) = $720 + $729.60 = $1,449.60/year — saving $326/year versus flat rate.

Tips & Best Practices

• ✓UK Economy 7 tariff: off-peak overnight electricity runs 7 hours (typically midnight to 7 AM or 1 AM to 8 AM). Economy 7 off-peak rates are often 35-50% lower than day rates. Best for homes with storage heaters, hot water immersion heaters, or overnight EV charging.
• ✓California TOU rates: Pacific Gas & Electric (PG&E) peak rates (4-9 PM weekdays) can reach $0.55-0.65/kWh. Off-peak rates fall to $0.15-0.25/kWh. Shifting a 7.2 kW EV charge from 6 PM to 11 PM saves: 7.2 kWh × ($0.55 - $0.20) = $2.52 per charge session, or $756/year for daily charging.
• ✓Solar export rate (feed-in tariff): in markets with solar net metering, excess solar electricity exported to the grid earns a credit at the export rate (often $0.05-0.12/kWh in the US, higher in some EU markets). Factor this credit into your net annual electricity cost when sizing solar systems.
• ✓Commercial demand charges: for businesses, electricity bills often have two components — energy (kWh × rate) and demand (peak kW × demand rate). This calculator models the energy component; demand charges require a separate peak kW analysis. Energy costs typically represent 50-70% of commercial electricity bills; demand charges 30-50%.

Who Uses This Calculator

Homeowners comparing flat-rate versus time-of-use electricity plans to determine which saves more money based on their actual consumption patterns. Businesses calculating annual electricity budget from utility billing data. Solar system owners calculating net annual electricity cost after accounting for solar production. Renters evaluating estimated utility costs before moving to a new location. Energy managers benchmarking facility electricity costs per year and per square foot for operational comparison.