TOU vs Tiered vs ULO Calculator | Ontario Electricity Explained

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TOU vs Tiered vs ULO Savings Calculator (Ontario)

Updated 2026-02-12

This calculator compares Time‑of‑Use (TOU), Tiered, and Ultra‑Low Overnight (ULO) pricing using your estimated monthly usage and how your kWh are spread across time periods. Enter your assumptions and see which plan is likely cheapest for your household.

Your usage

Monthly kWh used

TOU usage split (percent)

If your split doesn’t add to 100, it will normalize automatically. On‑peak % Mid‑peak % Off‑peak %

Tiered pricing

Tier 1 limit (kWh/month) Tier 1 rate ($/kWh) Tier 2 rate ($/kWh)

Rates (enter your assumptions)

TOU rates

TOU on‑peak rate ($/kWh) TOU mid‑peak rate ($/kWh) TOU off‑peak rate ($/kWh)

ULO rates

ULO on‑peak rate ($/kWh) ULO mid‑peak rate ($/kWh) ULO off‑peak rate ($/kWh) ULO ultra‑low overnight rate ($/kWh)

ULO usage split (percent)

ULO adds an “ultra‑low overnight” period. If you don’t know your split, start with a guess and adjust. On‑peak % Mid‑peak % Off‑peak % Ultra‑low overnight %

Other bill components (estimates)

Delivery charges ($) Global Adjustment ($)

Tip: If you charge an EV or run large appliances overnight, increase your ULO “ultra‑low overnight %” and see how the result changes.

How to use this tool

Use your monthly kWh from your bill.
Estimate your time‑period split. If you aren’t sure, start with a guess and adjust.
Enter rates/thresholds you want to test (these change over time).
Keep delivery/GA close to your typical bill so the totals feel realistic.

Educational estimator only. For official rate periods and current prices, consult your utility and regulator materials.