If you search for ASO on-page optimization advice, most guides focus on two things: the title and the keyword field. The subtitle gets a paragraph, maybe two, and usually just "use it for your second-most important keyword."

That's correct but incomplete. The subtitle is the second-highest weighted field in Apple's search algorithm — more impactful than the keyword field, less impactful than the title. And the majority of apps either leave it blank or use it for a marketing tagline that does nothing for search visibility.

This post covers what the subtitle actually does, how Apple uses it, what makes a good one, and the mistakes that make it useless.

What the Subtitle Is

The App Store subtitle is a 30-character field that appears directly below your app name in search results and on your listing page. It's visible to users — unlike the keyword field — which creates a dual purpose: it needs to work as both a ranking signal and a readable piece of copy.

That dual constraint is what makes the subtitle harder to optimize than the keyword field. The keyword field is invisible, so you can optimize it purely for algorithm. The subtitle is visible, so it also needs to make sense to a human who reads it.

Apple introduced the subtitle field in iOS 11. Eight years later, a large percentage of apps still don't use it correctly.

How Apple Weights the Subtitle

Apple doesn't publish exact weighting, but the observed pattern from rank-tracking data is consistent: keywords in the subtitle carry significantly more ranking power than the same keywords in the keyword field, and less ranking power than the same keywords in the title.

The practical implication: if you have a high-value keyword that doesn't fit in your 30-character title, the subtitle is where it goes. Not the keyword field.

Example: your app is a habit tracker. Your title is "Streaks — Habit Tracker." You have 30 more subtitle characters. "Daily Routine & Goal Tracker" targets additional queries ("daily routine," "goal tracker") with higher weight than those same terms would have in the keyword field.

The subtitle also participates in Apple's keyword combination logic. If your title contains "Habit" and your subtitle contains "Tracker Daily Routine," Apple can surface you for searches like "habit daily," "habit routine," and "tracker routine" — combinations Apple assembles from your fields, not just exact phrases.

The Tagline Problem

The most common subtitle mistake: using it as a brand tagline.

Examples of wasted subtitles:

"Your journey to better habits"
"Life, simplified."
"Do more. Stress less."
"The smart way to stay organized"

These read fine. They contribute zero to search ranking. Apple can't match "Life, simplified" to a user searching "productivity app daily planner." The words don't connect to anything users actually type.

Every character in the subtitle is a character that could be a keyword. "Life, simplified." is 17 characters — that's space for "planner organizer" or "task manager free" that would actually drive search impressions.

The tagline goes in your description, where it can influence conversion. The subtitle is for search.

What Makes a Good Subtitle

A well-optimized subtitle does three things:

1. Targets a high-value keyword not already in the title. If your title is "Focus Timer — Pomodoro," your subtitle shouldn't say "Pomodoro" again. That's a repeated word Apple already indexes. Target something adjacent: "Study & Work Session Timer" or "Deep Work & Productivity."

2. Is readable as human copy. Unlike the keyword field, users see the subtitle in search results. "study work productivity timer" reads like spam. "Study & Work Session Timer" reads like a real app name. You want the former's keyword coverage in the latter's format.

3. Fits within 30 characters exactly — or close to it. Like the keyword field, unused characters are missed opportunities. A 15-character subtitle is leaving ranking signal on the table.

Per-Locale Subtitles: Where Most Apps Fall Completely Flat

Every locale in App Store Connect has its own subtitle field. And for most apps, every non-English subtitle is either blank or copied from English.

A blank Japanese subtitle means:

No second-field keyword signal for Japanese searches
Your app relies entirely on the title and keyword field for Japanese ranking
You're leaving 30 characters of indexed signal empty in that market

For international ASO, per-locale subtitle optimization follows the same logic as per-locale keyword research: you need to find what Japanese (or German, or French) users actually search, and put that keyword in the subtitle for that locale — not a translation of your English subtitle.

A Japanese productivity app user might search for completely different terms than an American one. The subtitle for the Japan locale should reflect what Japanese users actually type, researched from Japanese App Store data.

How to Audit Your Subtitle Right Now

Open App Store Connect. For your app, check:

Your primary locale (English):

Is the subtitle field filled?
Does it contain at least one keyword users actually search for?
Is it different from words already in your title?
Is it close to 30 characters?

Your international locales:

Is the subtitle filled for Japan? Germany? France? Brazil? South Korea?
If yes: is it a translated version of your English subtitle (mostly useless) or a keyword researched for that specific market?
If no: that's a ranking gap you can close.

For most apps, this audit reveals two things: an English subtitle that's a tagline (easy fix — replace with a keyword), and international subtitles that are blank or wrong (harder fix — requires per-market keyword research).

Rewriting Your Subtitle: A Quick Framework

Start with keyword research for your category. Find the top 5–10 terms users search that aren't already in your title. Rank them by: volume × (1/difficulty) × relevance.

Take the top term that fits in 30 characters and reads naturally enough to show to a user. That's your new subtitle.

If you can fit two terms naturally ("Habit & Goal Tracker Daily"), even better — you're covering two keyword concepts in one field.

Then repeat the process for each international locale: research what users in that market search, find your top secondary keyword for that language, write a subtitle that fits 30 characters and reads naturally in that language.

Done properly per market, this takes 1–2 hours per locale. For 5–10 markets, it's part of a full localization project — which is exactly what LocalizeRank delivers: per-market keyword research, competitor gap analysis, and ready-to-paste metadata including the subtitle for every locale. Starting at $49 for 5 markets.

App Store Subtitle: The Most Underused Ranking Field in ASO On-Page Optimization