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When a team plans its first Japan campaign, the OS split is one of the earliest numbers they set. It is also one of the easiest to get wrong.
The shorthand is familiar. Japan leans iPhone, Korea leans Android. At the national level that is roughly true. As a planning input it is close to useless, because a national figure is an average across age groups, and your users sit inside one of them.
How much of Japan actually carries an iPhone
The answer depends on what you count.
Ask people which phone they actually use, and Japan comes out close to even. MMD Labo surveyed 34,838 people in August 2026 and found iPhone at 45.6% and Android at 54.1%. (MMD Labo, 2026) NTT Docomo’s Mobile Society Research Institute ran a separate survey in January 2026 and landed in the same place. (NTT Docomo, 2026) Two independent measurements, one answer.
So Japan is not an iPhone-dominant market. It is a near-even one.
Web traffic tells a different story, with iOS at roughly 60% of Japanese mobile page views. That measures activity rather than ownership, and the two should not be placed on the same axis. Every figure in this article is ownership.
Korea is the more lopsided of the two. Gallup Korea surveyed 1,675 people aged 13 and over in July 2026 and found Galaxy at 81% and iPhone at 19%. (Gallup Korea, 2026)
The split by age
Both countries lean the same way. The younger the user, the more likely the iPhone. What differs is everything after thirty.
In Korea, 53% of people in their twenties use an iPhone, and that is the only age band where iPhone leads. From there it falls steeply: 38% in the thirties, 16% in the forties, low single digits from fifty, and effectively nothing past sixty.
In Japan the same curve is far flatter. Teens and people in their twenties sit at 74.6%, and the entire band from thirty to sixty sits together at 43.4%. (MMD Labo, 2026) Lower than the younger group, but at no point does either platform disappear.
Averaged across every age, Korea lands at 19% and Japan at 45.6%. Those are the two numbers everyone quotes, and they are the two least useful for planning.
In Korea the operating system marks a generation. In Japan it divides every generation roughly in half.
Young women skew iPhone in both markets
Gender sharpens the picture further.
Among Japanese women in their twenties, 81% use an iPhone. (MMD Labo, 2025) In Korea the same group sits at 67%, against a national figure of 19%.
If young women are your core audience, iOS deserves the larger share of the budget in either market. If your users are mostly men, or mostly over thirty, Android does.
Japan has a variable Korea does not
Company-issued phones in Japan skew heavily toward iPhone: 72% at large companies and 58.7% at small and mid-sized ones. Handsets people buy for themselves lean slightly Android. (MMD Labo, 2026)
Part of Japan’s apparent iPhone strength is work hardware.
For a B2B or productivity app, that pushes the iOS weighting up. For a consumer app, the personal-purchase picture is the relevant one, and it sits a little below the headline number.
Four decisions before you set the split
First, fix the age and gender of your core users. The OS split follows from that, not the other way around. Set it in the other order and you have anchored a ratio with nothing behind it.
Second, weight iOS up if young women are central. Both markets agree on this one, and the gap against the national average is large in each.
Third, weight Android up if your users are mostly over thirty. This matters most in Korea, where the drop is steep.
Fourth, in Japan, do not treat either platform as secondary. A Korean-style allocation carried into Japan leaves close to half the market underfunded.
One note on comparability
Gallup Korea asks which brand people use, while the Japanese surveys ask which operating system, and the sample sizes differ by more than twentyfold. We have compared the shape of the curves rather than exact points, and have not carried either series across years, since Gallup Korea changed its fieldwork method this year. The Korean figure for women in their twenties rests on a subsample of 99 and is best read as a direction rather than a precise value.
Closing
Japan is an iPhone country was a sentence written by looking at people under thirty. Korea is an Android country was written by looking at people over thirty. Each is true of the group it describes and misleading everywhere else.
That is why we start Japan plans from local data rather than regional shorthand. The OS split gets decided early, it is expensive to revisit once creative and store assets are built on top of it, and the national average is the single number least likely to describe the people you are actually trying to reach.
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