Heat Pump Switchover Temp Calculator Skip to main content
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Mini-Split vs Propane, Gas & Oil Cost Calculator

Enter your electric rate and fuel prices, pick a published COP curve, and see the hourly operating cost of your heat pump against propane, natural gas, or oil at every outdoor temperature. The output is the switchover temperature: the point where backup heat becomes cheaper to run than the mini-split.

A side-by-side hourly operating cost estimator for a mini-split heat pump and up to three fossil-fuel backups (propane, natural gas, heating oil), driven entirely by your own utility rates and fuel prices. Heat pump efficiency falls as outdoor temperature drops, so the comparison is computed across the full temperature range using a COP-versus-temperature curve: pick from generic standard and cold-climate profiles, brand-flavored generic curves (Mitsubishi, Daikin, Fujitsu, LG, Gree), a handful of specific beta models, or enter a fully custom seven-point curve from your unit submittal data. The heating load can be held fixed or scaled with outdoor temperature from your floor area, ASHRAE climate zone, and build quality. The tool charts cost per hour for every enabled source, charts the COP curve itself, and reports the estimated switchover temperature where each backup fuel crosses the heat pump. Each fossil source carries its own price, AFUE efficiency, and fuel heat content. Results are estimates based on your inputs and published curve shapes, not measured performance of your specific installed system. Works in English and Spanish, with light/dark themes, share links, and PDF export. This tool also absorbed the scope of the former Energy Efficiency Calculator, which now redirects here.

Pro Tip: The switchover temperature is extremely sensitive to your electric rate and propane price, and both change season to season. A mini-split that beats $2.00/gal propane down to 5 F can lose to $1.40/gal propane at 25 F. Re-run the comparison every time you get a fuel delivery quote or a new electric tariff, and save the share link so you can update prices in seconds instead of rebuilding the inputs.

Estimate your actual BTU/hr heat load from past utility bills before sizing equipment

Heat Load from Bills Calculator →

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Mini-Split Efficiency & Cost Calculator
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Plan the Review

Open a source-aware checklist with tool, material, safety, permit, and qualified-review prompts.

Open Mini-Split Review Checklist →

How It Works

  1. Set the Heating Load

    Choose fixed load (enter a single BTU/hr figure) or scaled load, which estimates load from your floor area, ASHRAE climate zone, build quality, indoor setpoint, and design temperature, then scales it with outdoor temperature. If you already ran the Heat Load from Bills calculator, enter that BTU/hr value here as the fixed load.

  2. Enter Your Electric Rate and Pick a COP Curve

    Enter your all-in electric rate in $/kWh (use the full delivered rate from your bill, not just the supply charge). Then pick the COP preset closest to your unit: generic standard, generic cold-climate, a brand-flavored generic curve, or one of the specific beta models. If you have the manufacturer submittal sheet, enter a custom seven-point COP curve instead.

  3. Enable the Backup Fuels You Want to Compare

    Toggle on propane, natural gas, and/or heating oil. For each, enter your delivered price (per gallon, per therm or CCF, or per gallon of oil) and the AFUE efficiency of the appliance burning it. Fuel heat content defaults are editable.

  4. Read the Hourly Cost Chart

    The cost chart plots estimated cost per hour for the mini-split and each enabled fuel across the outdoor temperature range. Where the heat pump line crosses a fuel line is the switchover temperature for that fuel; above it the mini-split is the cheaper estimate, below it the backup wins.

  5. Check the COP Curve and the Switchover Readout

    The COP chart shows the efficiency curve you selected so you can sanity-check it against your unit specs. The results panel states the estimated switchover temperature for each enabled fuel, or reports that one source wins across the whole range.

  6. Share or Export

    The share button encodes all inputs into a URL so a coworker or customer opens the exact same comparison. PDF export produces a report with the inputs, curves, costs, and source notes.

Built For

  • A homeowner with a mini-split and a propane furnace deciding the thermostat changeover point for the season after a fuel price quote
  • An HVAC contractor showing a customer the estimated dollars-per-hour difference between their existing oil boiler and a proposed cold-climate heat pump
  • Comparing a standard mini-split against a cold-climate model by flipping COP presets and watching the switchover temperature move
  • A rural customer on $0.32/kWh electricity checking whether the heat pump actually saves money against $1.80/gal propane at all
  • Entering a custom COP curve from a manufacturer submittal to estimate operating cost for a specific quoted unit before purchase

Features & Capabilities

Switchover Temperature, Not Just a Single Cost Number

Heat pump efficiency is temperature-dependent, so a single seasonal cost comparison hides the answer that matters: at what outdoor temperature should you switch to backup heat. The tool computes the crossing point for each enabled fuel from the COP curve and your prices.

Published COP Curves Plus Full Custom Entry

Twelve presets: generic standard, generic cold-climate, brand-flavored generic curves for Mitsubishi, Daikin, Fujitsu, LG, and Gree, and several specific beta models, each a seven-point COP-versus-temperature curve. Or enter your own seven points from submittal data.

Three Backup Fuels at Once

Propane, natural gas (therms or CCF), and heating oil can all be enabled simultaneously, each with its own delivered price, AFUE, and editable heat content, so a dual-fuel or fuel-switching decision fits on a single page.

Fixed or Climate-Scaled Heating Load

Hold the load constant for a simple per-BTU comparison, or scale it with outdoor temperature from floor area, ASHRAE climate zone (1-8), and build quality, which makes the cost chart reflect that cold hours are also high-load hours.

Cost and COP Charts

An hourly-cost-versus-temperature chart for every enabled source and a separate chart of the active COP curve, in light or dark theme, both exported in the PDF report.

English and Spanish

Full bilingual interface, including the COP preset labels and result text.

Share Links and PDF Export

All inputs encode into a share URL with no account or server-side storage, and the PDF report captures inputs, results, and source notes for a customer file.

References

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Frequently Asked Questions

There is no universal number; it depends on your electric rate, your backup fuel price, the appliance AFUE, and the COP curve of your specific unit. With average US prices, a typical mini-split against propane often crosses somewhere between roughly 0 F and 25 F, but cheap electricity or expensive propane can push the switchover below any temperature your climate sees, and the reverse can push it above freezing. That sensitivity is exactly why this calculator exists: enter your own numbers and read your own crossing point.
Usually yes in mild and moderate temperatures, because a heat pump moving heat at a COP of 2.5 to 3.5 delivers far more BTU per dollar than burning propane at 90 percent AFUE in most rate environments. As the temperature drops, the COP falls and the comparison tightens. Enter your delivered propane price and electric rate and the chart shows the estimated crossing point for your situation.
COP (coefficient of performance) is the ratio of heat delivered to electricity consumed. A COP of 3 means 3 units of heat per unit of electricity. Heat pumps extract heat from outdoor air, and as that air gets colder there is less heat to extract and the compressor works harder, so COP falls. A typical unit might run a COP near 3 at 47 F and below 2 at 5 F. The calculator interpolates along a seven-point curve rather than assuming one fixed efficiency.
Start with Generic Standard for an ordinary mini-split or Generic Cold-Climate if your unit is marketed as a hyper-heat or low-ambient model. The brand-flavored presets are generic curve shapes informed by typical published data for those brands, not certified performance maps for a specific model. For a real decision, pull the COP or capacity table from your unit submittal sheet and enter a custom curve.
It was consolidated into this tool. The old page redirects here, and the fuel-versus-fuel operating cost comparison it performed is covered by enabling multiple backup fuels alongside the heat pump.
No. This tool compares operating cost of heat you are already able to deliver; it does not size equipment. Use the Heat Load from Bills calculator to estimate your BTU/hr load from utility bills, and have an HVAC contractor confirm sizing with a proper load calculation before purchasing.
Use the all-in delivered rate: total bill dollars divided by total kWh, or at minimum supply plus delivery charges. Using only the supply rate understates heat pump cost and produces a switchover temperature that is too optimistic.
This is an estimate built from your entered prices and a generic or user-entered COP curve. Your installed system has its own performance map, defrost behavior, duct or head losses, and real weather exposure. Treat the output as a planning estimate and verify against actual bills over a season or with an HVAC contractor.
Disclaimer: This is a cost-comparison estimator driven by the prices, efficiencies, and COP curve you enter, not a measurement of your installed system. The COP presets are generic published-curve shapes, not certified performance maps for specific models, and real-world output varies with defrost cycles, installation quality, and weather. Estimated switchover temperatures are planning figures; verify equipment selection, sizing, and dual-fuel changeover settings with a qualified HVAC contractor and your actual utility bills.

Learn More

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