Flat and tiered rates
A flat tariff applies one energy price, while tiers charge different prices after usage thresholds. Use the tier likely to apply to additional consumption.
Supply and delivery
Some bills separate generation or supply from delivery. Both may vary with kWh, so include both when estimating incremental appliance cost.
Use a scenario range
When a rate is uncertain, calculate low and high cases. A range is more honest than treating a national average as a local fact.
Use the numbers
Apply this guide with one of WattMeasure’s free calculators. Results are planning estimates and should be verified for consequential decisions.
Last reviewed August 6, 2026