Everyday Calculators
Electricity Usage Rate Calculator
Reconstruct a three-period electricity statement from allocated kWh and period rates, then show peak share and the effective cost per consumed kWh.
Total time-of-use electricity (kWh)-
Off-peak energy charge-
Shoulder-period energy charge-
Peak energy charge-
Total time-of-use energy charge-
Bill before taxes after credit-
Taxes and surcharges-
Estimated time-of-use electricity bill-
All-in cost per consumed kWh-
Peak electricity share-
Decision view
Time-of-use day and bill composition
Time-of-use day and bill compositionOff-peak, shoulder, and peak periods share one daily tariff clock and reconcile separately to the all-in electricity statement.
Exact scenario comparisonPeak electricity use (kWh) changes while all other entered assumptions remain constant.
| Peak electricity use (kWh) | Total time-of-use electricity (kWh) | Off-peak energy charge | Shoulder-period energy charge | Peak energy charge | Total time-of-use energy charge | Bill before taxes after credit | Taxes and surcharges | Estimated time-of-use electricity bill | All-in cost per consumed kWh | Peak electricity share |
|---|
How to use Electricity Usage Rate Calculator
- Allocate interval usage to the correct tariff periods.
- Enter recurring fixed fee and only confirmed bill credit.
- Reconcile the estimated bill and peak share with the statement.
Calculator guide
Understanding Electricity Usage Rate Calculator
A time-of-use bill should expose off-peak, shoulder, and peak quantities, their prices, the fixed fee, confirmed credit, tax, and final all-in rate.
Detailed calculation process
Reconstruct a three-period time-of-use statement
The default prices 420 off-peak, 180 shoulder, and 90 peak kWh, then adds an $18 fixed fee, subtracts a confirmed $12 credit, and applies 4% tax.
General formula: E = E_o+E_s+E_p; C = E_o r_o+E_s r_s+E_p r_p; S = max(C+F-K,0); B = S(1+t); r_eff = B/E; q_p = E_p/E Each time period is priced separately. The fixed fee and credit affect the subtotal, while the effective rate spreads the complete modeled bill over all consumed kWh.
What each symbol means
Worked substitution with the default inputs
The default statement totals about $137.90, with an all-in effective rate near $0.1999 per kWh and 13.04% of energy in the peak period.
Load shifting
Identify which kWh can move
Time-of-use savings usually come from changing timing, not just total use.
Worked situations
Practical examples
- 420 off-peak kWh at $0.13 costs $54.60.
- A credit reduces the subtotal before entered tax.
- Peak share is peak kWh divided by all entered kWh.
Better inputs
Useful tips
- Check weekends and holidays in the tariff calendar.
- Use interval exports rather than estimates.
- Test whether flexible loads can move out of peak.
Before relying on the result
Limitations and common mistakes
- Demand charges, tiers within periods, minimums, exports, losses, and special tax rules are excluded.
- The user supplies correct period allocation.
- The credit is assumed fully available.
Reference
Key terms
- Off-peak
- Lowest-priced entered tariff period.
- Shoulder
- Intermediate entered tariff period.
- Peak share
- Peak kWh divided by total kWh.
- Effective rate
- Final modeled bill divided by total kWh.
Important note
Tariff references: OpenEI Utility Rate Database (https://openei.org/wiki/Utility_Rate_Database) and U.S. Energy Information Administration, Electricity Prices Explained (https://www.eia.gov/energyexplained/electricity/prices-and-factors-affecting-prices.php). The provider's published time windows and tariff govern the bill.
Frequently asked questions
Why can effective rate exceed the off-peak rate?
Peak and shoulder charges, fixed fee, and tax raise the all-in result.
Should exported solar kWh be negative?
No. Export compensation needs a separate tariff model.
What if the credit exceeds charges?
The modeled subtotal is floored at zero before tax.
Does peak share measure cost share?
No. It is an energy share; peak cost share can be higher.
How should kWh be assigned to tariff periods?
Use interval meter data and the provider's exact weekday, weekend, holiday, and seasonal clock definitions.
Can the effective rate be compared with another tariff?
Yes, only when both calculations include comparable usage, fees, credits, taxes, and billing periods.