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.
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.
What is the difference between TOU, Tiered, and ULO?
Ontario households can choose from several electricity pricing structures, and each one rewards different usage patterns. Time-of-Use (TOU) pricing changes the electricity rate depending on the time of day. Tiered pricing keeps the rate structure simpler by charging one price up to a monthly usage threshold and a higher price above that threshold. Ultra-Low Overnight (ULO) pricing adds a very low overnight rate, which can be helpful for households that can shift meaningful usage into late-night hours.
This means the “best” plan depends less on the size of your home and more on when you use electricity. A household that charges an electric vehicle overnight may benefit more from ULO, while a household with steady daytime usage may prefer Tiered or TOU depending on its patterns.
Why timing matters as much as total usage
Many people focus only on total monthly kWh, but timing can matter almost as much as volume. Two households may use the same amount of electricity in a month and still pay different energy charges if one runs major appliances during on-peak periods and the other shifts more of that usage into off-peak or overnight periods.
This is why calculators like this one are useful. They allow you to test different assumptions and see whether moving flexible loads — such as laundry, dishwashing, or EV charging — could change which pricing plan is cheapest.
What this calculator does and does not show
This calculator is designed as an educational planning tool. It helps compare likely monthly totals under TOU, Tiered, and ULO assumptions using estimated rates, usage splits, delivery charges, and Global Adjustment values.
It does not replace a real utility bill. Actual Ontario electricity bills depend on current rate schedules, seasonal thresholds, local utility delivery structures, and regulatory adjustments that can change over time. Use this tool to compare scenarios, not to predict an exact invoice amount to the penny.
When ULO pricing may make sense
ULO pricing is often most attractive for households that can consistently use electricity during ultra-low overnight periods. This may include homes with electric vehicles, programmable water heating, or appliances that can be scheduled late at night. If overnight usage is only a small share of the household total, ULO may not outperform TOU or Tiered pricing.
A good way to test this is to increase the overnight percentage in the calculator and compare the results. If the gap remains small, the added complexity of changing habits may not be worth it. If the savings become meaningful, the pricing change may deserve closer consideration.
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