How Watt Owl Calculates Your Electricity Costs
Most electricity comparison sites show you the same three numbers: the average price at 500, 1,000, and 2,000 kWh per month. These are the breakpoints the Public Utility Commission of Texas (PUC) requires providers to publish on every plan's Electricity Facts Label (EFL).
Those numbers are a starting point, but they don't tell you what a plan is likely to cost you. A plan that looks cheap at 1,000 kWh might be expensive at 800 kWh because of a usage credit that kicks in at 1,000. Another plan might have a low energy rate but a high monthly base fee that makes it costly for smaller households.
Watt Owl does the math differently.
Our Data Sources
Every rate estimate on Watt Owl is built from official regulatory documents — the same documents your provider files with the State of Texas.
Electricity Facts Labels (EFLs)
Every electricity plan sold in Texas comes with an Electricity Facts Label. This is a PUC-mandated disclosure document that contains the plan's complete pricing structure: energy charges, base fees, usage credits, tiered rates, and any other billing components.
We analyze these EFLs to extract the individual billing rules that determine your monthly cost. Instead of relying on the three pre-calculated averages, we use the underlying pricing components to calculate an estimate at any usage level.
Delivery Charges (TDSP Tariffs)
Your electricity bill has two parts: the energy charges from your Retail Electric Provider (REP) and the delivery charges from your local Transmission and Distribution Service Provider (TDSP). Some plans bundle delivery charges into their advertised rate. Others list them separately.
We track the current regulated tariff schedules for all major Texas TDSPs — Oncor, CenterPoint Energy, AEP Texas, and TNMP — using rates filed with the PUC. When we estimate your bill, we include delivery charges for your specific service territory so the number you see reflects a more complete estimate.
How We Calculate Your Estimated Bill
For each plan, we build up your estimated monthly cost from individual billing components:
- Energy charges — the per-kWh rate for the electricity you consume
- Base fees — fixed monthly charges that apply regardless of usage
- Delivery charges — regulated TDSP fees for transmitting power to your home
- Tiered rates — plans where the per-kWh rate changes at certain usage thresholds
- Usage credits — discounts that apply when your usage exceeds a specific level (e.g., a $50 credit at 1,000 kWh)
- Time-of-use rates — plans where pricing varies by time of day or day of week
We combine these components at your specific usage level to produce a single estimated monthly bill. This means the cost you see for a plan at 850 kWh is calculated from the actual billing rules — not interpolated between the 500 and 1,000 kWh breakpoints.
Why This Matters
Consider two plans:
- Plan A: 8.0¢/kWh energy rate + $10/month base fee, no credits
- Plan B: 10.0¢/kWh energy rate + $0 base fee, $25 credit at 1,000 kWh
At 1,000 kWh, Plan B looks cheaper ($75 vs. $90). But at 800 kWh, Plan A costs $74 and Plan B costs $80 — and Plan B's advertised "average price" won't tell you that, because EFL averages are only shown at 500, 1,000, and 2,000 kWh.
Our calculator handles these scenarios because it works from the billing rules, not the summary numbers.
How We Validate Accuracy
We don't just calculate bills — we verify that our calculations are correct.
For every plan we publish, we compute estimated bills at the standard PUC breakpoints (500, 1,000, and 2,000 kWh) and compare them against the prices published in the plan's official EFL. Plans must match within a reasonable tolerance to appear on our site.
Plans that don't pass this validation check are not shown to consumers. This means every plan you see on Watt Owl has been checked against its official regulatory filing.
How We Rank Plans
By default, plans on Watt Owl are ranked by lowest estimated monthly bill at your usage level. This is a straightforward sort: whichever plan we estimate will cost you the least appears first.
We do not accept payment to rank plans higher. Our broker disclosure explains how we're compensated and how that does — and doesn't — affect what you see.
Top Picks Categories
On ZIP code pages, we highlight three plans to help you get started:
- Best Value — the plan with the lowest estimated monthly bill at your usage, among plans with 12-month terms. We exclude plans with usage-based credits or fees from this category because those create rate discontinuities that can be misleading at a single usage level.
- Best Short Term — the lowest-rate plan with a contract under 12 months, for shoppers who want flexibility.
- Top Green — the lowest-cost 100% renewable plan on a 12-month term.
These are generated automatically from our calculation engine. No provider pays for placement in these categories.
HootScore: Our Trust Rating
Every plan on Watt Owl receives a HootScore from 0 to 100. This composite rating helps you compare plans beyond price alone, covering four dimensions that matter for a good electricity experience.
Price Transparency (40% of score)
We measure how consistent a plan's pricing is across different usage levels. Plans with flat, predictable rates score highest. Plans where the effective rate swings dramatically between 500 and 2,000 kWh — often due to bill credits that create artificial price dips — score lower.
We calculate the coefficient of variation across the three standard EFL breakpoints (500, 1,000, and 2,000 kWh). Plans with a CV below 0.05 score 95-100. Plans above 0.30 score under 40.
Plans that exhibit a "bill credit trap" pattern — where the 1,000 kWh rate is lower than both the 500 and 2,000 kWh rates — receive an additional penalty because their advertised rates can be misleading.
Fee Fairness (25% of score)
This measures how much a plan relies on fees rather than straightforward energy pricing:
- Base charge (40% of sub-score): Monthly fixed fees before any electricity usage. $0 scores 100; over $15/month scores 20.
- Early termination fee (40% of sub-score): The cost to cancel your contract early. $0 scores 100; over $200 scores 20.
- Usage-based fees or credits (20% of sub-score): Plans without conditional charges score 100; plans with them score 40.
Contract Flexibility (20% of score)
Shorter commitments score higher. Month-to-month plans score 100; contracts over 24 months score 20. Plans with longer terms but no early termination fee receive a 20-point bonus, since the contract length is effectively a suggestion.
Green Energy (15% of score)
This is a direct mapping of the plan's renewable energy percentage. A 100% renewable plan scores 100; a 0% plan scores 0.
What HootScore Does Not Measure
- Customer service quality — we don't have reliable data on hold times, billing accuracy, or complaint resolution speed
- Future price changes — we score the current plan as filed; variable-rate plans may change
- Network reliability — delivery infrastructure is managed by your TDSP, not your REP
- Promotional offers — sign-up bonuses, gift cards, or other incentives are excluded
Update Frequency
HootScores are recalculated daily as part of our data pipeline. When a plan's EFL is updated or a new complaint scorecard is published, scores are refreshed accordingly.
What Our Estimates Include — and Don't Include
Included in our estimates:
- Energy charges at your specified usage level
- All base and fixed monthly fees disclosed in the EFL
- TDSP delivery charges (fixed and per-kWh) for your service territory
- Usage credits and tiered rate adjustments
- Time-of-use period weighting (for TOU plans)
Not included in our estimates:
- Taxes (varies by municipality)
- Late payment fees, disconnection/reconnection charges
- One-time enrollment or setup fees
- Charges that depend on payment method (e.g., non-autopay surcharges)
- Usage beyond your entered amount (we estimate for one month at the level you specify)
All estimates on Watt Owl exclude applicable taxes.
How Often We Update
Plan data is refreshed daily. When a provider files a new plan or updates an existing one, we analyze the updated EFL and recalculate pricing. Plans that are withdrawn or expired are removed from our listings.
TDSP delivery rates are updated when the PUC approves new tariff schedules — typically a few times per year.
Our Independence
Watt Owl is a licensed retail electric broker registered with the Public Utility Commission of Texas (Broker #BR260022). We are not a Retail Electric Provider — we don't sell electricity. We compare plans from dozens of providers across the deregulated Texas market and earn a commission when you enroll through our site.
Our rankings are based on estimated cost, not on which providers compensate us. We show plans from providers regardless of whether they have a commercial relationship with us. For full details, see our broker disclosure.
Always verify plan details, rates, and terms directly with your provider before enrolling.
Have questions about our methodology? Contact us at hello@wattowl.com.