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Energy Cost & Equipment Sizing Calculators
Free energy cost and equipment sizing calculators. Electricity cost, EV charging cost, heating fuel comparison (gas vs electric vs oil vs propane), generator sizing, whole house generator sizing. For facility managers, homeowners, and energy auditors.
Energy cost and equipment sizing calculators help homeowners, facility managers, energy auditors, and electrical contractors make informed decisions about energy consumption, fuel selection, and backup power. Our free tools cover electricity cost estimation, EV charging cost comparison, heating fuel cost analysis (natural gas vs electric vs oil vs propane), generator sizing for commercial buildings, and whole-house standby generator sizing — all built on EIA, DOE, NEC, and EPA reference data.
The most transformative change in building energy economics is the heat pump. At a COP of 3.0, a heat pump delivers heat at $11.72/MMBTU (at $0.12/kWh), compared to $17.65/MMBTU for an 85% AFUE natural gas furnace (at $1.50/therm). But these economics shift dramatically with regional energy prices — in the Northeast with expensive electricity and moderate gas prices, gas still dominates. Our heating fuel comparison calculator handles all four major fuels with adjustable efficiency inputs.
Generator sizing is the critical calculation before every backup power installation. The generator must handle both steady-state running load and the momentary starting surge of the largest motor (typically the air conditioner compressor at 4-6× FLA). A 4-ton AC that draws 4.5 kW running may require 18-22 kW momentarily during startup — this starting surge, not the running load, often determines the minimum generator size.
Energy Cost & Equipment Sizing Quick Reference
| Metric | Typical Value | Reference |
|---|---|---|
| US avg electricity | $0.12/kWh residential | EIA 2025 |
| US avg natural gas | $1.50/therm residential | EIA 2025 |
| Electricity (industrial) | $0.06-0.08/kWh | EIA 2025 |
| EV home charging (per mile) | $0.03-0.04/mile | At $0.12/kWh |
| Gasoline (per mile) | $0.10-0.15/mile | At $3.50/gal, 30 MPG |
| Residential generator | 20-26 kW | Whole-house with AC |
| Commercial generator | 100-2000+ kW | Varies by load |
| Heat pump COP | 2.5-4.5 (varies with outdoor temp) | AHRI rated at 47°F |
Energy Cost & Equipment Sizing Calculators (5)
Electricity Cost Calculator | kWh to Dollars
Electricity cost calculation bridges the gap between a piece of equipment's nameplate wattage and the real...
EV Charging Cost Calculator | Electric Car Charge Cost
Charging an electric vehicle costs far less per mile than fueling a gasoline car — typically 2.5-4x cheaper at...
Generator Sizing Calculator | Standby & Prime Power (kW/kVA)
Generator sizing is a multi-constraint optimization problem balancing steady-state running load, motor...
Heating Fuel Cost Calculator | Gas vs Electric vs Oil vs Propane
Comparing heating fuel costs on an apples-to-apples basis requires converting all fuels to a common unit: cost...
Whole House Generator Sizing Calculator | Residential Standby
Whole-house generator sizing for residential standby power ensures all home systems remain operational during...
Frequently Asked Questions
Is it cheaper to heat with gas or a heat pump?
At US average prices: natural gas at $1.50/therm with an 85% AFUE furnace costs $17.65/MMBTU delivered. A heat pump with COP 3.0 at $0.12/kWh costs $11.72/MMBTU — about 33% cheaper. However, at $0.25/kWh (Northeast/California) and $1.00/therm gas, the gas furnace costs $11.76/MMBTU vs the heat pump at $24.41/MMBTU — gas wins. Always calculate with your local utility rates.
What size generator for a whole house?
Essential circuits (fridge, lights, furnace blower, sump pump, electronics): 7-10 kW. Whole house with central AC up to 4 tons using soft start: 20-22 kW. Whole house with 5-ton AC, no soft start: 26-30+ kW. Large luxury home with multiple AC units, pool, EV charger: 30-48 kW. The most popular residential size is 22-26 kW (air-cooled) — it handles essential + AC with soft start at a reasonable installed cost ($10,000-15,000).
How much does it cost to charge an EV?
At the US average $0.12/kWh: a full charge of a 60 kWh battery costs ~$8.00. More commonly, a 20-80% daily charge costs ~$5.00. Per mile: ~$0.03-0.04. A comparable 35 MPG gasoline car at $3.50/gallon costs $0.10/mile. Annual savings over 15,000 miles: ~$1,000/year. With home solar, the marginal cost approaches zero (foregone net metering credit of $0.03-0.05/kWh).
How do I calculate the payback of energy efficiency upgrades?
Simple Payback = Upgrade Cost ÷ Annual Energy Savings. Example: Replacing a standard-efficiency 50 HP motor (89% eff) with a NEMA Premium motor (93% eff) saves: 50 HP × 0.7457 × (1/0.89 - 1/0.93) × 8,000 hr/yr × $0.07/kWh = $1,202/year. If the premium motor cost is $1,500 more, payback = $1,500 ÷ $1,202 = 1.25 years. For most industrial energy efficiency measures, lifecycle cost (purchase + 20-year energy) is dominated by energy — the purchase price is nearly irrelevant compared to the operating cost.