SolarToolsHow This Tool Works
The Electricity Bill Estimator predicts your monthly bill from a list of appliances, their wattage, daily usage hours, and your local rate. It's the right tool when you're moving to a new home, planning a major appliance purchase, or auditing why your bill jumped $80 last month. Instead of relying on the utility's monthly statement to surprise you, this calculator lets you model your consumption forward.
The tool ships pre-loaded with 8 common appliances (fridge, lights, AC, water heater, TV, dryer, dishwasher, WiFi) at typical usage values. Edit any row to match your actual home. Add custom appliances using the "+ Add appliance" button. The right panel updates live showing your estimated monthly bill, daily kWh, and a bar chart of which appliances contribute most.
Beyond the basic per-kWh charge, the calculator handles two real-world complications: the fixed monthly customer charge that utilities bill regardless of usage (typically $10–$25), and tiered pricing where usage above a threshold kicks into a higher rate (common in California, Hawaii, and parts of South Africa). Set the Tier 2 threshold to 0 if your rate is flat.
Pair this with the Appliance Wattage Lookup to find accurate wattage for any device, and the Energy Audit Calculator for a more detailed breakdown including standby loads and seasonal variation.
- Start with the presets. The 8 pre-loaded appliances cover ~70% of typical household consumption. Adjust the wattage and hours to match your home.
- Add missing appliances. Common adds: pool pump, EV charger, space heater, dehumidifier, chest freezer. Use the Appliance Wattage Lookup for accurate values.
- Enter your local rate. US average: $0.16/kWh. California: $0.30. Hawaii: $0.42. Pacific Northwest: $0.11. South Africa: ~R2.80/kWh (~$0.15).
- Set the fixed charge. Check your bill — it's usually $8–$25/month regardless of usage.
- Tier 2 pricing: if your utility charges more above a certain kWh threshold (common in CA), enter the threshold and higher rate. Set threshold to 0 for flat-rate plans.
The bar chart on the right shows which appliances dominate your bill. For most homes the top three are AC, water heater, and dryer — together usually 50–60% of total kWh. Cutting AC runtime by 2 hours/day or switching to a heat pump water heater can drop the bill 20–30%.
When to Use This Calculator
The kWh formula
Energy in kWh = (watts × hours) / 1000. A 1500W space heater run for 4 hours uses 6 kWh. At $0.16/kWh that's $0.96/day or $28.80/month — for one appliance. The calculator sums this across all your appliances and multiplies by 30 for the monthly total.
Why estimates can be off by ±20%
Three sources of error. First, duty cycles — a fridge doesn't draw 400W continuously; it cycles on 30–50% of the time. Our preset values use average duty-cycled wattage, but your specific appliance may differ. Second, seasonal variation — AC runs 8 hours in July and 0 in October. The calculator gives a 30-day average; summer bills will be higher, winter bills (with electric heat) much higher. Third, standby loads — small always-on devices (chargers, smart speakers, set-top boxes) collectively add 30–80W continuously, which is 1–2 kWh/day and rarely tracked. For exact accounting, use a Sense or Emporia whole-home monitor.
Tiered vs time-of-use
Tiered pricing (California, Hawaii) charges more per kWh above a threshold. TOU pricing charges more during peak hours. They're different mechanisms and the calculator only handles tiered. For TOU, use the Time-of-Use Optimizer after estimating total kWh here.
The customer charge
That $12 fixed charge on your bill isn't a fee for nothing — it covers the utility's cost of maintaining your connection (meter, billing, wires to your house) regardless of how much you use. Even at zero kWh, you pay it. It's also why going off-grid has a real cost: you're no longer paying that $12/month, but you're paying $40,000+ upfront for your own infrastructure. The Off-Grid Designer shows the full math.
How to actually reduce your bill
Three high-impact moves: (1) switch to a heat pump water heater (saves 60% of water heating kWh), (2) raise AC setpoint 2°F in summer (cuts AC kWh ~10%), (3) replace electric resistance heat with a heat pump (cuts heating kWh 60–70%). For details on each, see the Energy Audit Calculator and Heat Pump Payback Calculator.
Frequently Asked Questions
Typically ±20% versus your actual bill. Main sources of error: appliance duty cycles (your fridge may cycle differently than the average), seasonal variation (the calculator gives a 30-day average), and untracked standby loads. For exact tracking, install a Sense or Emporia whole-home energy monitor.
Common reasons: you forgot to add your pool pump, EV charger, or electric space heater; your AC runs longer than 6 hours/day in summer; your water heater is older and less efficient; or you're on a time-of-use plan and most of your usage hits peak rates.
Check your most recent bill — it's listed as a per-kWh charge, often broken into generation, transmission, and distribution. Add them up. Or check your utility's website. The US EIA publishes average state rates monthly.
Partially — commercial bills also include demand charges (peak kW draw) which this calculator doesn't model. For commercial use, multiply the energy portion by 1.3–1.5 to roughly account for demand charges.
Run the calculator twice — once with summer inputs (AC running, no heating) and once with winter inputs (heating, no AC). Average the two for an annual number, or track them separately to predict which months will be expensive.
Further Reading
Deep-dive articles and guides related to this calculator.
Understanding Time-of-Use Electricity Rates: Save Money by Shifting Load
How TOU pricing works, why utilities use it, and how much you can save by shifting dishwasher, laund...
Cutting Your Electricity Bill: 12 Strategies That Actually Work
Twelve proven strategies to cut your electricity bill, ranked by ROI. From free behavioral changes t...
Reading Your Electricity Bill: Understanding Every Line Item
Decoding every line on your electricity bill: generation, transmission, distribution, demand charges...
Energy & Solar Glossary
Plain-English definitions of every term used in this calculator and across the site.