Mini-Split Running Cost: What a Ductless Heat Pump Costs to Run per Month

Mini-Split Running Cost: What a Ductless Heat Pump Costs to Run per Month

By EnergyBS Editorial Team | November 13, 2026

The Short Answer

Short Answer: A 2-ton (24,000 Btu/h) ductless mini-split carrying its full design heating load costs roughly $130 a month in a mild-winter month, $175 in a mixed-climate winter month and $250 in a cold-climate January at the U.S. average residential electricity price of 18.16 cents per kWh (EIA, August 2026). Cooling the same space costs about $40 to $95 a month in a hot-climate summer month, depending on the unit's SEER2. Those figures come from one formula, kWh = heat load ÷ efficiency, and they move in direct proportion to your price per kWh: at Maine's 32.11 cents every heating number above rises by about 77%.

The useful part is not the headline number but the method, because no two homes share a load, a climate or a rate. The rest of this page gives you the three conversions that turn an efficiency rating into kWh, the price per million Btu of heat in 13 states and two Canadian provinces, a monthly cost table by system size and climate, one heating and one cooling example worked line by line, and the break-even efficiency against baseboard, oil, propane and natural gas.

Three Conversions That Do All the Work

Every running-cost estimate for a mini-split is built from three numbers: how much heat the home needs moved, how efficiently the equipment moves it, and what a kWh costs. The efficiency part is where most online estimates go wrong, because mini-split ratings are written in three different units.

COP (coefficient of performance) is the plain ratio: units of heat delivered per unit of electricity used, both in the same unit. A COP of 2.5 means 1 kWh of electricity delivers 2.5 kWh of heat, which is 2.5 × 3,412 = 8,530 Btu. Electric baseboard heat has a COP of exactly 1. COP is an instantaneous figure that changes with outdoor temperature.

HSPF2 (Heating Seasonal Performance Factor 2) is the US heating rating on the yellow EnergyGuide label: Btu of heat delivered over a standardized heating season per watt-hour of electricity. DOE moved the industry from HSPF to HSPF2 on January 1, 2023, with a test procedure that the Federal Energy Management Program describes as defined in 10 CFR part 430. Because there are 3,412 Btu in a kWh, seasonal COP = HSPF2 ÷ 3.412.

SEER2 (Seasonal Energy Efficiency Ratio 2) is the cooling equivalent: Btu of heat removed over a standardized cooling season per watt-hour. kWh for cooling = Btu removed ÷ (SEER2 × 1,000).

The ENERGY STAR floors in the table come from its current key product criteria for air-source heat pumps, read November 13, 2026: at least 7.8 HSPF2, 15.2 SEER2 and 11.0 EER2 for split systems, and for cold-climate non-ducted systems at least 8.5 HSPF2, a COP of at least 1.75 at 5°F, and at least 70% of the 47°F heating capacity still available at 5°F. NEEP's cold-climate specification (Version 4.0, in effect since January 1, 2023) is the other list most utility programs use; its product listings publish the COP and capacity of each model at 5°F and 17°F, which is the data you want when your winters are cold. Our cold-climate heat pump performance data guide explains how to read those columns, and SEER2 and HSPF2 explained covers why the 2023 numbers look lower than the old ones for the same machine.

One caution about HSPF2. It describes a single standardized test climate. In a winter colder than that climate, your seasonal COP will be lower than HSPF2 ÷ 3.412; in a milder one, higher. That is why the tables below assign a different COP to each climate rather than using the label figure everywhere.

Price Your Heat per Million Btu First

Before anything about system size, convert your electricity price into the cost of a fixed amount of heat. A million Btu (1 MMBtu) is a convenient unit: it is about what a small, well-insulated home might use on a cold week, and it is how EIA and most fuel comparisons are expressed.

Dollars per MMBtu delivered = cents per kWh × 293.1 ÷ COP (because 1,000,000 ÷ 3,412 = 293.1 kWh per MMBtu at COP 1, and dividing cents by 100 gives dollars).

The table uses EIA's August 2026 residential average prices by state, the latest state figures published when we recorded them. August prices are summer prices; some utilities charge less per kWh in winter and some charge more, so check your own bill.

Two notes on the Canadian rows, both in Canadian dollars.

Quebec. Hydro-Quebec's Rate D, effective April 1, 2026, charges 7.065 cents per kWh for the first 40 kWh per day and 11.142 cents above that, plus a system access charge of 46.154 cents per day (as published in the Hydro-Quebec rate schedule and reported by a secondary source; Hydro-Quebec's web page did not show the figures to us, so confirm there). The first tier is calculated over the whole billing period: 40 kWh × 62 days = 2,480 kWh for a two-month bill. A home that already uses its first tier on lights, appliances and hot water heats with second-tier power, which is why the table uses 11.142 cents. The Regie de l'energie approved a 3.0% residential increase for April 2026 and loaded more of it onto the second tier, which nudges winter heating costs up slightly more than the average.

Ontario. The Ontario Energy Board's Regulated Price Plan prices from November 1, 2026 are 9.1, 14.6 and 18.9 cents per kWh for off-peak, mid-peak and on-peak time-of-use, or 11.2 cents for the first 1,000 kWh a month in winter and 13.2 cents above it on the tiered plan. Those are commodity prices only. Your local distributor's delivery charges, part of which vary with kWh, are added on the bill, and the provincial Ontario Electricity Rebate comes off it. The Ontario row therefore understates the true marginal cost by the variable part of your delivery charge; take that figure from your own bill. Our Ontario electricity rates guide walks through each line, and a mini-split that does most of its work overnight and on weekends can run largely at the 9.1-cent off-peak price.

Monthly Heating Cost by System Size and Climate

To turn a price per MMBtu into a monthly bill you need the monthly heat load. The cleanest homeowner method uses heating degree days (HDD), the same measure utilities use to weather-adjust bills:

Monthly heat (Btu) = design heat loss (Btu/h) ÷ design temperature difference (°F) × monthly HDD × 24

The table assumes each system is sized to match its zone's design heat loss, so a "2-ton" row is a zone that needs 24,000 Btu/h on the coldest design day. The three climates are illustrations with stated inputs, not data from a particular city:

• Mild: a 450 HDD month, design temperature difference 35°F, seasonal COP 3.0
• Mixed: a 750 HDD month, design temperature difference 50°F, seasonal COP 2.6
• Cold: a 1,200 HDD month, design temperature difference 70°F, seasonal COP 2.1

The lower COP in the cold column is deliberate. A cold-climate unit must hold at least 1.75 at 5°F to earn the ENERGY STAR cold-climate label, and it spends more of a cold month in defrost and at high compressor speed. Your city's monthly HDD is on NOAA climate summaries or your gas or power bill.

How to read it. Pick the row whose size matches the zones the mini-split actually heats, not the outdoor unit's nameplate. A 3-ton multi-zone outdoor unit serving a main floor that needs 18,000 Btu/h on the design day belongs in the 1.5-ton rows. Then scale the price column to your rate: cost changes in exact proportion to cents per kWh.

Three reasons the table can overstate your bill. Degree days at a 65°F base assume the house needs heat whenever it is below 65°F outside; well-insulated homes with internal gains from people, appliances and sun often need none until it is closer to 55°F. Most installers also size a mini-split with some margin, so the zone's real design load is often below the head's rating. And many mini-splits share the load with another heat source, which takes the coldest hours.

Two reasons it can understate it. A house that leaks more air than its design heat loss assumed uses more heat than the formula says, and a unit that drops to its electric resistance backup (some ducted heat pumps have strips; most ductless heads do not, but a home may run baseboards alongside) pays COP 1 prices for those hours.

Monthly Cooling Cost by System Size and Climate

Cooling is simpler because SEER2 already folds in a season's mix of part-load and full-load operation. The inputs are equivalent full-load cooling hours in the peak month: the hours the unit would have to run flat out to remove that month's heat. The three climates are again illustrations with stated inputs: 350 hours for a hot-climate July (long days near the design temperature, as across much of Texas, Florida and Arizona), 200 hours for a warm-climate July, 90 hours for a mild one.

The formula behind each kWh figure: capacity (Btu/h) × full-load hours ÷ (SEER2 × 1,000). For the 2-ton hot row at SEER2 16: 24,000 × 350 ÷ 16,000 = 525 kWh.

Cooling costs less than heating for the same size of system for two reasons: summer loads are smaller than winter loads in most of the US and Canada, and a heat pump moves heat across a much smaller temperature difference in July than in January, so its efficiency is higher.

Worked Heating Example: Adding a Mini-Split to an Oil-Heated Home in Maine

Illustration with stated inputs.

A Maine household heats with an oil boiler and used 700 gallons last winter. It installs a 2-ton cold-climate mini-split on the main floor and expects the mini-split to take over about 60% of the home's heat, leaving the boiler for upstairs bedrooms and the coldest nights.

Step 1: How much heat did the oil deliver? 700 gallons × 138,500 Btu per gallon × 85% boiler efficiency = 82.4 MMBtu delivered.

Step 2: How much does the mini-split take over? 60% × 82.4 = 49.4 MMBtu, which displaces 420 gallons of oil.

Step 3: kWh to deliver that heat. At a seasonal COP of 2.2: 49.4 × 1,000,000 ÷ 3,412 ÷ 2.2 = 6,587 kWh. At a seasonal COP of 2.6: 5,574 kWh.

Step 4: Cost. At Maine's August 2026 average of 32.11 cents: $2,115 at COP 2.2 or $1,790 at COP 2.6.

Step 5: Oil saved. 420 gallons at EIA's U.S. winter forecast of $5.26 a gallon = $2,209.

Result: a saving of $94 a year at COP 2.2 and $419 at COP 2.6. That is a real saving, but a much smaller one than a typical sales sheet promises, and it hinges on two numbers. Maine's electricity price is near the top of the country; at the Northeast's winter forecast average of 26.19 cents, the same heat costs $1,725 at COP 2.2 and the saving rises to $484. And COP: every 0.1 of seasonal COP is worth roughly $80 a year in this house.

The break-even COP against oil at these prices is the price per MMBtu from baseboard heat divided by the price per MMBtu from oil: $94.11 ÷ $44.68 = 2.11. Below a seasonal COP of 2.1, the Maine household would pay more to heat with the mini-split than with oil. The way to stay well above it is to let the mini-split carry the shoulder seasons and mild winter days, where its COP is often above 3, and to hand the coldest nights to the boiler. That is the dual-fuel logic covered in our heat pump backup heat guide.

Worked Cooling Example: A Texas Bedroom Wing

Illustration with stated inputs.

A Texas home adds a 1.5-ton two-head mini-split to a bedroom wing the central AC never cooled well. The heads are rated SEER2 20. In July the wing's cooling load equals 330 hours at full capacity.

kWh: 18,000 Btu/h × 330 h ÷ (20 × 1,000) = 297 kWh.

Cost: 297 × 15.91 cents = $47 for the month.

If the old arrangement was the central system running longer to drag the bedrooms down, the comparison is not with zero. Suppose the central AC, rated SEER2 14, had to remove the same 5.94 million Btu: 5,940,000 ÷ 14,000 = 424 kWh, or $67. The mini-split saves about $20 a month on that heat alone, and more if the central system can now be set a few degrees warmer for the rest of the house. If it cannot, and the mini-split is pure added comfort, the $47 is a new cost.

How Inverter Part-Load Operation Changes the Bill

A conventional single-stage air conditioner or heat pump is either at 100% or off. A mini-split's inverter compressor varies its speed; the Building America Solution Center notes that inverter compressors can ramp down to as little as 10% of rated capacity. That changes running cost in three ways.

It is usually more efficient at part load. At low speed the coils are oversized relative to the refrigerant flow, so the temperature lift the compressor has to create is smaller and the machine delivers more heat per kWh. Most of a heating season is part load. This is the main reason a mini-split's seasonal efficiency beats its full-speed rating.

It loses that advantage when it cycles. Once the zone's load drops below the compressor's minimum speed, the unit starts and stops like a single-stage machine, and each start wastes some energy. This is the cost of an oversized head in a small room. Our head placement guide shows how three small bedrooms on a multi-zone system can sit below that floor, and the organizing guide explains why one head per zone, rather than one per room, keeps more heads in their efficient range.

It punishes deep setbacks. With a furnace, setting the thermostat back overnight saves fuel because the furnace is equally efficient whenever it runs. With a mini-split, the morning recovery runs the compressor at full speed, where its COP is lowest, and on a cold morning that is also when the outdoor coil is most likely to frost. A modest setback of 2 to 3°F, or none, usually costs less than a 10°F setback followed by a hard recovery. Your own bill is the test: try a steady setpoint for two weeks and compare kWh per degree day.

How Defrost Changes the Bill

In heating mode the outdoor coil is colder than the outdoor air. When the air is near or below freezing and humid, moisture freezes on the coil, which blocks airflow and cuts capacity. The unit periodically reverses to melt it, briefly taking heat from the house to do so; the indoor fan usually stops so the room is not blown with cool air. You may see steam rising from the outdoor unit, which our defrost cycle explainer covers in detail.

Defrost energy is a real cost and it is not spread evenly. It is greatest in damp weather around freezing, not on the coldest dry days, because dry, very cold air carries little moisture to freeze. Two practical consequences for running cost:

• The outdoor unit needs space for meltwater to drain and must not sit where it refreezes into a block of ice around the base. A raised stand and a clear drain path are installation details that show up on the bill.
• A unit running in defrost far more often than its neighbours, or with ice that never fully clears, has a problem (low charge, a failed sensor, blocked airflow) and is burning electricity on it. That is a service call, not a running-cost assumption.

The cold column of the monthly heating table already uses a lower COP (2.1) partly to reflect defrost. If you are pricing a unit for a humid, cold coastal climate, use the model's NEEP-listed COP at 17°F as a sanity check rather than its HSPF2.

When a Mini-Split Beats Baseboard, Oil, Propane or Gas

The break-even seasonal COP against any fuel is: (cost of electric resistance heat per MMBtu) ÷ (cost of that fuel's delivered heat per MMBtu). Delivered heat per MMBtu for a fuel = price per unit ÷ (heat content per unit × appliance efficiency). Using EIA's 2026-27 winter forecast prices and EIA heat contents:

Regional prices move these thresholds a lot:

The decision rules that fall out of the two tables:

1. Baseboard heat: always switch the load you can. Any functioning mini-split delivers more than one unit of heat per kWh, so every MMBtu moved from baseboards to a mini-split costs less. Natural Resources Canada's ENERGY STAR page puts the saving for certified ductless heat pumps at about 60% less energy than standard electric resistance heat. In the monthly table, the 2-ton cold-climate case is $250 against $526 for the same heat from baseboards.
2. Oil: usually yes, but check your rate. At U.S. average prices the mini-split wins at a COP of 1.2, a figure even a basic unit beats until the very coldest hours. At Maine's August price the bar rises to about 2.1, as the worked example showed, and a cold-climate model matters.
3. Propane: yes in most places for most of the season. The South's break-even of 1.26 is easy; the Northeast's 2.03 is met on most winter days by a cold-climate unit and missed on the coldest ones.
4. Natural gas: usually no on running cost alone. A seasonal COP of 3.2 to 4.7 is needed, which only holds in the mildest climates. A mini-split can still make sense in a gas home for cooling, for a room the furnace heats badly, or as the shoulder-season heat source with the furnace as backup, but not as a bill-cutting replacement at current prices. Our heat pump vs gas furnace operating cost comparison works the full-house version.

These break-evens use energy prices only. Fixed monthly charges for a gas or propane account, tank rental and delivery minimums can tip the decision if a mini-split lets a household drop a fuel entirely, and a time-of-use or heat pump rate from your utility can lower the electricity price below the averages used here.

For the full set of regional winter forecasts behind these numbers, see our winter heating cost forecast by fuel.

Estimate Your Own Monthly Cost in Five Lines

Take last winter's bills and this worksheet:

The last-line check: compare against your utility's kWh history after the first full month. If actual use is far above the estimate, look for a setback habit, a head short-cycling in a small room, a blocked filter (dirty filters cut airflow and efficiency, which is why DOE's purchasing guidance lists filter replacement as part of keeping peak performance), or a baseboard still switching on underneath.

What This Page Does Not Count

• Fixed charges. Your electricity bill's customer charge is paid whether or not the mini-split runs. Only variable charges belong in running cost.
• Standby power. Indoor heads draw a little power on standby for their controls and Wi-Fi; on a large multi-zone system this is small but not zero. The model's specification sheet lists it.
• Crankcase or base-pan heaters. Some cold-climate outdoor units run a small heater in very cold weather to protect the compressor and keep the drain pan clear. It adds kWh in the coldest weeks; the installation manual or specification sheet gives its wattage and when it switches on.
• Installation cost and rebates. These change the payback but not the monthly running cost. See our mini-split installation cost guide and, for Ontario, our Ontario heat pump cost guide. The US federal 25C tax credit ended for property placed in service after December 31, 2025, so do not count it in a 2026 payback.

Frequently Asked Questions

How many kWh does a mini-split use per month?

It depends on the load and the efficiency. A 2-ton unit carrying its full design load uses about 720 kWh in a mild winter month, 970 kWh in a mixed-climate month and 1,380 kWh in a cold-climate January under the assumptions in our table. For cooling, the same unit uses about 380 to 525 kWh in a hot-climate July depending on whether it is rated SEER2 22 or SEER2 16.

How much does a mini-split cost to run per hour?

At full speed, divide the capacity by 3,412 and by the COP at that temperature, then multiply by your price. A 12,000 Btu/h head heating at COP 2.5 draws about 12,000 ÷ 3,412 ÷ 2.5 = 1.41 kW, or about 26 cents an hour at 18.16 cents per kWh. Most hours it runs below full speed, so the average hour costs less.

Is a mini-split cheaper to run than baseboard heat?

Yes, for every hour it runs at a COP above 1, which is every hour a working unit is not in defrost. At the U.S. average price, heat from baseboards costs $53.22 per MMBtu and heat from a mini-split at COP 2.5 costs $21.29, a 60% saving that matches the figure Natural Resources Canada gives for ENERGY STAR ductless units.

Is a mini-split cheaper than oil heat?

At U.S. average forecast prices for winter 2026-27, yes, above a seasonal COP of 1.2. In Maine, where August 2026 power averaged 32.11 cents, the break-even rises to about 2.1, and a cold-climate model running most of the winter well above that is what makes the switch pay.

Is a mini-split cheaper than natural gas?

Usually not on running cost alone at current prices. Against a 95% furnace it needs a seasonal COP of about 3.9 at U.S. average prices and about 4.7 in the Northeast and Midwest, which few units sustain through a cold winter. The South, with cheaper power and pricier gas, is closer at about 3.2.

Does turning a mini-split off when I leave save money?

For a short absence, often not much, because the recovery runs the compressor at full speed where efficiency is lowest. For days away, set it to a lower holding temperature rather than off, which also protects against frozen pipes in winter.

Do multi-zone systems cost more to run than single-zone ones?

Per unit of heat, a multi-zone combination can carry a lower rating than the best single-zone pairings, and small heads on a large outdoor unit cycle more at low load. The difference depends on the models and the layout; compare the AHRI-rated HSPF2 and SEER2 of the exact combination quoted.

What efficiency should I use for my cold-climate home?

Use the NEEP-listed COP at 17°F as a typical cold-month figure and the COP at 5°F as the floor for the coldest nights. ENERGY STAR's cold-climate label requires at least 1.75 at 5°F.

Related Reading

• Mini-Split Maintenance and Cleaning Guide
• How to Organize a Ductless Mini-Split System
• Ductless Mini-Split Head Placement Guide
• Ductless Mini-Split Installation Cost 2026
• Cold Climate Heat Pump Performance Data
• SEER2 and HSPF2 Explained
• Winter Heating Costs 2026-27 by Fuel and Region
• Space Heater Cost to Run per Hour and Month
• Heat Pump Defrost Cycle Explained
• Heat Pump vs Gas Furnace Operating Cost