# How much will a mini split add to my electric bill?

> What a mini split adds to a Portland electric bill: PGE and Pacific Power rates, the cost of heat against baseboards and gas, and the break-even efficiency.

URL: https://firlandsportlandminisplits.com/guide/mini-split-electric-bill/

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Running costs worked out from PGE, Pacific Power and NW Natural rates, against baseboards and a gas furnace.

Last Updated: November 12, 2026

The short answer

It depends on what the mini split replaces. Against electric baseboards, a heat pump delivers the same heat for roughly a third to half the electricity, so the bill drops. Against a gas furnace, it comes out close: on PGE's rates a heat pump has to average a COP near 2.8 to match gas, on Pacific Power's about 2.3.

Key takeaways

- Baseboards turn one kWh into one kWh of heat; a mini split moves two to four.
- PGE's residential energy charges add up to about 17.1 cents per kWh; Pacific Power's about 14.0.
- Against a 95% gas furnace, the break-even COP is about 2.8 on PGE and 2.3 on Pacific Power (derived).
- Cooling costs little in Portland's short summers.

Before people commit to a heat pump, they want to know what happens to the bill. At [Firlands Portland Mini Splits](https://firlandsportlandminisplits.com/) we won’t promise a savings number, because it turns on your house, your habits and what you heat with now. What we can do is show the arithmetic with the rates Portland actually pays.

## The short answer: it depends on what it replaces

A mini split’s running cost is mostly heating. What it does to your bill depends on whether it takes over from baseboards, a gas furnace, or nothing at all.

| If the mini split replaces | Likely effect on energy cost |
| --- | --- |
| Electric baseboards or wall heaters | Lower for the same heat, often by half or more |
| A gas furnace | About even; it turns on the heat pump’s real efficiency and your utility |
| Window AC units | Lower for the same cooling; inverter heads are far more efficient |
| Nothing (a room that had no heat or cooling) | A new cost, usually modest |

## How efficiency is measured

Heat pump efficiency comes down to one idea: how much heat you get for each unit of electricity.

### COP, HSPF2 and SEER2

- **COP (coefficient of performance)** is heat delivered divided by electricity used, at a moment. A COP of 3 means three kWh of heat for every kWh. Baseboards have a COP of 1.
- **HSPF2** is the heating efficiency over a rated season, in BTU per watt-hour. Dividing it by 3.412 gives a seasonal COP: an HSPF2 of 8.1, Energy Trust’s floor for its ductless incentive, works out to about 2.4.
- **SEER2** is the same idea for cooling. A SEER2 of 20 means 20,000 BTU of cooling per kWh over the rated season.

### Ratings versus your house

Ratings come from a standard test season, not Portland’s. A heat pump’s COP drops as it gets colder outside, and rises in mild weather.

Portland’s winters are mild for a heat pump: the airport’s December-to-February average is about 42.5°F, and it falls to 20°F or below only about one night a year. That’s why we choose [cold-climate models](https://firlandsportlandminisplits.com/guide/do-mini-splits-work-in-cold-weather/) for heads that heat, and size them for the 24°F design low.

## Portland’s electric and gas rates

Most of Portland is on PGE; most of Northeast Portland, Piedmont and the downtown core are on Pacific Power. Their per-kWh charges differ, and that changes the math.

| Utility | Energy charge used here | What it includes |
| --- | --- | --- |
| PGE, residential default plan | About 17.1 cents per kWh | Transmission, distribution, energy and the power-cost adjustment, from PGE’s tariff filing with the Oregon PUC |
| Pacific Power, Oregon residential | About 14.0 cents per kWh | Delivery and supply, system benefits and Energy Trust charges, less the BPA credit, from Pacific Power’s Oregon price summary |
| NW Natural, residential gas | About $1.71 per therm, derived | Worked out from the Oregon PUC’s figures for a typical 54-therm month, fixed charge included |

All three change from season to season, and each carries a monthly basic charge on top. Your own bill is the best source for your rate. In Vancouver, Clark Public Utilities sets its own rates.

## Cost per unit of heat, worked out

The fairest comparison is the cost of 100,000 BTU of heat delivered into the house, about one therm. These figures are derived from the rates above.

| Heat source | PGE customer | Pacific Power customer |
| --- | --- | --- |
| Electric baseboard (COP 1) | $5.01 | $4.11 |
| Mini split averaging COP 2.5 | $2.00 | $1.64 |
| Mini split averaging COP 3.0 | $1.67 | $1.37 |
| 95% gas furnace, NW Natural | $1.80 | $1.80 |

### Against baseboards

Any heat pump beats baseboards on energy cost, because any COP above 1 is cheaper per BTU. At a seasonal COP of 2.5, each unit of heat costs about 40% of what baseboards charge.

Energy Trust of Oregon also pays an incentive when a ductless heat pump replaces electric resistance heat in the main living space ([mini split rebates in Oregon](https://firlandsportlandminisplits.com/guide/mini-split-rebates-oregon/)).

### Against a gas furnace

Here it’s close. Dividing the baseboard cost by the gas cost gives the break-even seasonal COP: about 2.78 on PGE and 2.28 on Pacific Power. Above that, the heat pump costs less to run; below it, gas does.

One caveat matters. The gas figure spreads NW Natural’s monthly fixed charge across every therm. If you keep gas for a water heater or a range, that charge stays, so each therm the furnace stops burning saves a little less than $1.71. That pushes the break-even COP a bit higher.

## What a month might look like

Here’s a worked example, using the figures above, for a house whose baseboards use 1,000 kWh in a cold month.

1. **Baseboards:** 1,000 kWh ([replacing baseboards](https://firlandsportlandminisplits.com/baseboard-heat-to-mini-split/) is where this matters most), about $171 on PGE or $140 on Pacific Power.
2. **Mini split averaging COP 2.5:** the same heat for 400 kWh, about $68 on PGE or $56 on Pacific Power.
3. **The difference:** about $100 on PGE in that month, before basic charges.

Your numbers will differ with the weather, the house and how you set the heads. This is arithmetic, not a promise.

### Cooling

Cooling costs little here. Portland’s airport averages about 15 days a year at 90°F or above. A [single-zone](https://firlandsportlandminisplits.com/single-zone-mini-split-installation/) head at SEER2 20 cooling a bedroom with 50,000 BTU overnight uses about 2.5 kWh, roughly 43 cents at PGE’s rate.

## Getting the lowest bill from a mini split

How you run the heads matters nearly as much as which ones you buy.

- **Hold a steady temperature.** Inverter heads are most efficient running slowly all day, not off and on.
- **Clean the filters.** A clogged filter cuts airflow and efficiency ([cleaning and maintenance](https://firlandsportlandminisplits.com/mini-split-cleaning-maintenance/)).
- **Size it right.** An oversized head short-cycles; an undersized one leans on backup heat ([mini split sizing](https://firlandsportlandminisplits.com/guide/mini-split-sizing/)).
- **Keep the outdoor unit clear.** Leaves, snow and shrubs choke the coil.
- **Look at time-of-day pricing.** PGE and Pacific Power offer optional plans with cheaper off-peak hours; a heat pump that holds steady through the evening peak can sometimes benefit.

For the up-front side, see the [cost guide](https://firlandsportlandminisplits.com/guide/mini-split-installation-cost-portland/) or try the [cost estimator](https://firlandsportlandminisplits.com/tools/mini-split-cost-estimator/), and for replacing baseboards room by room, [baseboard heat to mini split](https://firlandsportlandminisplits.com/baseboard-heat-to-mini-split/).

## Questions about this guide

### Is it cheaper to run a mini split or electric baseboards?

A mini split. Baseboards turn each kWh into one kWh of heat. A heat pump moves heat from outdoors and typically delivers two to four kWh of heat per kWh it uses, depending on the outdoor temperature. The same warmth costs less.

### Should I leave my mini split on all the time?

In most cases, yes, at a steady setting. Inverter heat pumps are most efficient holding a temperature at low speed. Turning one off all day and back on in the evening makes it run hard, and in heat mode can bring on lower-efficiency operation.

### Does a mini split cost much to run for cooling in Portland?

No. Portland's airport averages about 15 days a year at 90°F or above, and cooling demand is a fraction of heating demand. Worked through at PGE's rate, a modern head cooling a bedroom overnight uses well under a dollar of electricity.

## Related service

- [Service**Baseboard to mini split** Replace baseboard heat with a mini split: ductless heads take over in the rooms that use the most heat, and add cooling.](https://firlandsportlandminisplits.com/baseboard-heat-to-mini-split/)

## More guides

- [Cost Guide**How much does mini split installation cost in Portland?** Typical ranges by job, what moves the number, and the public costs inside it.](https://firlandsportlandminisplits.com/guide/mini-split-installation-cost-portland/)
- [Learn**What mini split rebates are available in Oregon?** What Energy Trust pays, which homes qualify, how state and city programs work, and what's changed for the federal credit.](https://firlandsportlandminisplits.com/guide/mini-split-rebates-oregon/)
- [Learn**Do mini splits work in cold weather?** Portland's winters are mild with sharp exceptions: freezing rain, an east wind and a few nights in the teens.](https://firlandsportlandminisplits.com/guide/do-mini-splits-work-in-cold-weather/)

## Get an estimate for your house

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