Two islands, both off the west coast, both reachable in a morning from Glasgow, both offering mountains and coast and a distillery or two. They get requested interchangeably at this desk, sometimes in the same sentence. The request that arrives is almost always some version of a week, a car, somewhere to walk, and the assumption sitting underneath it is that arran or mull is a question of size, with the larger one holding the fuller week.
What the request usually leaves out is the road surface. Nobody thinks to mention it, because on a map both islands look like a loop you drive around. One of those loops is two lanes for nearly its whole length. The other is not. That single detail rearranges almost everything else on this page, including how many places you can stay, how far the ferry sails, and how much of the island a Sunday to Sunday actually reaches.
The other thing left out is the crossing. People treat the ferry as the thing that happens before the holiday starts. On one of these islands it is fifty five minutes and runs several times a day. On the other, the shortest routing is forty six minutes but requires a drive of three and a half hours to reach the port, and the alternative saves the drive at the cost of a longer sail. That is a whole day of your seven, spent one way or another.
The two halves, set on the same axes
arran
Crossing is 55 minutes from Ardrossan against roughly 45 minutes from Oban plus the drive to Oban itself; the coast road is 56 miles and closes the loop, so no day needs a second ferry; Goat Fell is 2,866 feet and the standard path up and back is about five hours; the island is 19 miles by 10, which is why one base covers it and why the week costs $2,120 rather than more.
from $2,120 per person
mull
Mull is roughly 338 square miles against Arran's 167, so the same map inch costs twice the time; the crossing from Oban is 46 minutes on a large vehicle ferry against 55 minutes from Ardrossan to Brodick, but the drive to Oban from Glasgow is about 2 hours 40 against 45 minutes to Ardrossan; the road to Iona and Fionnphort is single track with passing places for 35 of its 37 miles and takes 1 hour 40 each way from Craignure; Mull has no through ring road, so every day out is a there-and-back, and the ferry to Iona is a second, separate crossing.
from $2,290 per person
Two figures set beside each other are two facts about two different trips of different lengths, run by different companies, in different seasons. Neither figure is offered as the better value and this office will not say that one is. What each covers is listed on its own page.
An hour of driving buys different amounts of ground
Arran is about 167 square miles. Mull is about 338, roughly twice the land and, counting the peninsula that runs west toward Iona, far more coastline than that ratio suggests. On area alone Mull looks like the bigger week.
Then the road. Arran's coast road is a continuous loop of roughly 56 miles, mostly two lanes, and a competent driver rounds it in about two hours without stopping. That means every point on Arran is inside an hour of every other point, and a base anywhere on the island reaches the whole of it. Mull's main artery, the A849, is single track with passing places along long stretches, and the road out to Fionnphort for the Iona crossing is single track for most of its 36 miles. That drive takes about an hour and a half in good conditions, longer behind a slow vehicle you cannot pass until the next widening. Tobermory in the north to Fionnphort in the southwest is around 50 miles and budgets at two hours, one way.
So the arithmetic inverts. Twice the land, but each mile costs roughly twice the time, which puts more of Mull outside comfortable reach of any single base than is true of Arran at half the size. A week on Arran can genuinely cover the island. A week on Mull covers a portion of it well, or the whole of it thinly, and choosing which is the real planning decision.
The rest of what changes between them
Ardrossan to Brodick, about 55 minutes, several sailings daily in summerferry, shortest crossing
Oban to Craignure, about 46 minutes, several sailings daily, plus shorter northern routes
Ardrossan is roughly 45 minutes from Glasgow by road or traingetting to the port
Oban is roughly 2 hours 30 minutes to 3 hours from Glasgow, so most people lose a half day either side
about 167 square milesland area
about 338 square miles
coast loop of about 56 miles, largely two lanes, drivable in roughly 2 hoursmain road
A849 and the Iona road, single track with passing places over long stretches, Tobermory to Fionnphort about 2 hours
around 8 to 10 villages around the loop, with the largest concentration at Brodicksettlements with a spread of places to stay
concentrated heavily in Tobermory, with thinner provision at Salen, Craignure, Bunessan and Fionnphort
effectively the entire island, including both halves of the ridgewhat a week reaches from one base
one region properly, or the whole island with long driving days
the northern half is mountainous, with the highest ground around 2,866 feet, and the ridge holds weather that the southern coast does notexposure
lower and broader overall, with the high ground around 3,169 feet at Ben More, and long open runs where wind off the Atlantic reaches the road directly
Holy Isle from Lamlash, a short hop, weather dependentside trips by boat
Iona from Fionnphort at about 10 minutes, plus Staffa and the Treshnish Isles as separate seasonal sailings
Two requests that point somewhere else entirely
Some of what arrives phrased as this question is not this question. If either of these is you, the comparison above is the wrong page and a different conversation is a better use of your week.
What we will do with your dates
We will not tell you which one to take, and we are not going to imply it either. The two islands answer different questions and only you know which question you are asking. What we will do is take your dates, your party size and your vehicle, and put both islands in writing on a single sheet: the sailings that actually exist on your days, the crossing lengths, what accommodation is available in the areas you would realistically base yourself, and honest driving times between the places you have named. Costs are quoted from, per person, and confirmed at booking. Then you look at the two columns and decide, with the arithmetic already done. Write to the desk with your dates and we will start it.