Straight out of the search data, and the answer is a number rather than a word, which is why there is a calculator for it.
The running cost calculator asks for the unit's power, how long you run it and what you pay per unit of electricity, and gives you a cost per hour, per night and per summer in pounds. It defaults to the current price cap but you can type your own rate over it, which is worth doing: the cap is an average and almost nobody pays exactly it.
The thing that surprises people is not the hourly cost, it is the hours. A unit running eight hours a night through a hot fortnight is a very different bill from the same unit run for an hour before bed.
There is also a diagram on the site showing why a single hose portable unit works harder than a double hose one for the same cooling, which is the part of the answer no price comparison covers.
What does your meter say, against what the calculator says? That gap is the interesting bit.