Enrichment · Passion Projects · Home and money

Same kilowatt-hours,
three plans,
one cheapest.

Type your monthly use and the rates on offer. The calculator prices the month on each plan and shows how much of your use can fall in on-peak hours before time of use stops saving money.

Compare the plansWhat you get

The tariff comparison

The worked example is made up: an 850 kWh month with 30% of use on-peak. The rates are examples, not any utility’s. Nothing you type leaves this browser.

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What you get

Enrichment · Passion ProjectsFree

What you finish with
Each plan’s monthly cost and average price per kWh, the cheapest plan and the yearly difference, and the break-even on-peak share. It prints as a summary and downloads as a spreadsheet.
Who it is for
Families and students with their first utility bills, personal finance and economics students, and environmental science students studying peak demand.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The Passion Projects space in Caveat Enrichment.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Find a month’s kWh on the bill.
  2. Find your on-peak share from usage data, or estimate it.
  3. Type each plan’s rates and monthly charge from the rate sheet.
  4. Read the cheapest plan and the break-even share.
  5. Try a lower on-peak share to see what shifting use would save.

Compare the plans

How the plans are priced

One month of use, three price lists.

The worked example: 850 kWh, 30% on-peakFlat$152.25$12 + 850 × 16.5¢Time of use$159.05$12 + 255 × 32¢ + 595 × 11¢Two-tier$146.50$10 + 500 × 14¢ + 350 × 19¢Break-even26.2%on-peak share, flat = TOUThe worked example: 850 kWh, 30% on-peakFlat$152.25$12 + 850 × 16.5¢Time of use$159.05$12 + 255 × 32¢ + 595 × 11¢Two-tier$146.50$10 + 500 × 14¢ + 350 × 19¢Break-even26.2%on-peak share, flat = TOU
Each plan is the same use priced differently. Time of use rewards moving use out of the on-peak hours, so its cost depends on your on-peak share.

The three shapes

A flat plan charges the same for every kWh. Time-of-use plans charge more in on-peak hours, often late afternoon and evening, when the grid is busiest, and less at other times. Tiered plans charge a lower rate for the first block of use each month and more beyond it. Most add a fixed monthly charge.

The break-even share

Time of use is cheaper than flat only if enough of your use is off-peak. Setting the two costs equal and solving for the on-peak share gives the line: below it, time of use wins. Laundry, dishwashers, pool pumps and electric-car charging are the easiest loads to move. Taxes and riders on the bill usually apply to every plan alike.

Sources

  1. U.S. Energy Information Administration. Electricity explained: factors affecting electricity prices and time-of-use rates (eia.gov).
  2. U.S. Department of Energy. Time-based rate programs and smart meters (energy.gov).
  3. U.S. Energy Information Administration. Electric Power Monthly: average residential price (eia.gov).
  4. Consumer Financial Protection Bureau. Budgeting for utility bills (consumerfinance.gov).

The worked example and its rates are made up. Plans differ by utility; read the full rate sheet. Your figures stay in this browser. Support: team@caveatacademic.com.