Free tool · 2026

Portable vs Fitted Air Conditioning Calculator

A portable is cheap to buy and expensive to run. This works out what each option really costs you over the years you will actually use it.

Open the calculator Read the running costs guide

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True cost over timeRunning cost includedNo-install option covered100% free · no sign-up

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Portable or fitted? Work it out in 30 seconds

4 steps. Unit type, how many summers, how much you run it, and region.

Method

How this calculator works

Portables look cheap because the whole cost is visible on day one. A fitted split hides its advantage in the running cost: a portable draws close to its full 1.0–1.5kW almost continuously and vents through a hose that lets warm air back in around the window seal, while a split modulates down to 0.3–0.7kW once the room is at temperature.

So the honest comparison is not purchase price, it is total cost over the number of summers you will actually use it. That is what this calculates, at around 26p/kWh (the July 2026 price cap).

A portable remains the right answer in a rented flat, where no external unit is permitted, or for genuine emergency cooling. The calculator will tell you when that is the case rather than pushing you toward an install.

2026 costs

Portable vs fitted (2026)

Purchase and running cost side by side. Running figures assume ~26p/kWh electricity.

Option	Typical 2026 cost	Notes
Portable unit	£200–£500	No installation; draws 1.0–1.5kW near-continuously
Portable running cost	£90–£160 per summer	Roughly 26–40p an hour
2.5kW fitted split	£1,500–£2,600	Installed; quieter and heats in winter
Fitted split running cost	£30–£70 per summer	Roughly 8–23p an hour, less once the room is cool
Crossover	~15–25 summers	On running cost alone, ignoring comfort and heating

Figures match our running costs guide and single split cost guide.

FAQs

Portable vs fitted calculator FAQs

Are portable air conditioners worth it?+

For occasional cooling, a rented flat, or where no external unit is allowed, they are the only realistic option. For a room you will cool every summer for years, a fitted split is quieter, cools properly and costs far less to run.

Why do portables cost so much to run?+

They draw close to full power most of the time, and the exhaust hose lets warm air back in around the window seal. A fitted split modulates down once the room is at temperature.

Do I need permission for a portable?+

Normally not — nothing is fixed and nothing is drilled. Anything with an external condenser needs the landlord's consent in a rental, and in a flat usually the freeholder's too. Our planning permission guide covers the rules for fitted units.

Can a portable heat as well?+

Some claim to, but poorly and expensively. For heating and cooling from one unit, a reversible split is the system that actually does it.

How much does a portable air conditioner cost to run?+

A 1.0–1.5kW portable at around 26p/kWh costs roughly 26–40p an hour, or £90–£160 over a typical UK summer. A 2.5kW fitted split draws about 0.7–0.9kW at full output and much less once the room is at temperature — roughly £30–£70 over the same summer.

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