ASO Basics You Can Still Ask About: Character Limits and Keyword Optimization for iOS and Android

When working on ASO (App Store Optimization) for your app, are you applying your iOS settings to Android as they are? In fact, the App Store and Google Play differ greatly in their metadata specifications and in how their search indexes work.

Even for the same app, each store needs its own optimization strategy. This article explains the foundations of ASO, “character limits” and “how indexing works”, and the differences between iOS and Android.

Differences in Metadata Fields and Character Limits

First, let’s compare the metadata fields you can set in each store and whether they are searchable.

Store	Field	Characters	Searchable
iOS (App Store)	Title	30	Yes
iOS (App Store)	Subtitle	30	Yes
iOS (App Store)	Keyword field	100	Yes
iOS (App Store)	Description	4,000	No
Android (Google Play)	Title	30	Yes
Android (Google Play)	Short description	80	Yes
Android (Google Play)	Full description	4,000	Yes

At a glance they look similar, but what matters is not the character count but what is searchable. Even fields with the same name differ greatly in function and importance from store to store.

How Indexing Works and What Is Searchable

Index Strength on iOS (App Store)

On iOS, only 160 characters are searchable (title 30 + subtitle 30 + keyword field 100). The 4,000-character description has no effect on search at all.

Title (30 characters)

The title has the greatest influence on search ranking and is the first thing users see. Keywords placed here are weighted most heavily in search rankings, so be sure to include your most important keyword.

However, cramming in keywords hurts readability and can actually lower your conversion rate. Aim for a balance of your brand name and one or two main keywords. Also, depending on the device, the title may be cut off at around 20 characters on screen, so put the most important information first.

Subtitle (30 characters)

The subtitle is the next most influential field for search ranking after the title. Placing secondary keywords that you didn’t use in the title here widens the range of searches your app can appear in.

Avoid overlapping with the title. For example, if the title contains “workout log”, use different related keywords in the subtitle, such as “gym”, “exercise” or “meal tracking”. It is common to join two to four keywords with a separator such as a dash or an ampersand.

Keyword field (100 characters)

The keyword field is the defining feature of iOS ASO. Users cannot see it, since it exists only in the management console, but it is searchable, so always fill it in. Its index strength is lower than the title and subtitle, but it is a valuable space for related terms and long-tail keywords that the title and subtitle can’t cover.

Key points for setting it up:

• Separate with commas only: workout,log,meal (no spaces needed)
• Duplicates are meaningless: workout log,meal log,workout → “workout” and “log” are repeated and wasted
• Words are combined for search: entering workout,log,meal lets your app match “workout log”, “meal log” and “workout meal”
• Avoid overlap with the title and subtitle too: re-entering a word that is already there has no effect

Description (4,000 characters)

The iOS description has no effect on search. You therefore don’t need to think about keywords at all and can focus on writing an appealing description that makes users want to install the app.

Conversion rates improve when you state user benefits clearly, explain concrete features, and align the content with your screenshots. If you have social proof such as user numbers, ratings or awards, include it.

Index Strength on Android (Google Play)

On Android, a total of 4,110 characters (title 30 + short description 80 + full description 4,000) are all searchable. In contrast to iOS, the full description has a large effect on search.

Title (30 characters)

On Android too, the title is the field with the greatest influence on search ranking. The big difference from iOS is that the entire 4,000-character full description is searchable.

You don’t need to force keywords that the full description can cover into the title. Prioritize a title that is easy for users to read and understand, and choose your most important keyword carefully. Keeping it readable lets users grasp what the app is about instantly, which also helps conversion.

Short description (80 characters)

The short description is the 80 characters of text shown directly below the title. Its direct effect on search ranking is unclear, but it is an important message area that users see before expanding the full description, and it has a large effect on conversion.

Convey the app’s appeal concisely and write a line that makes users want to know more. Show concrete features and benefits, and use as much of the 80-character limit as you can.

Full description (4,000 characters)

The defining feature of Android ASO is that all 4,000 characters of the full description are searchable. On iOS the description does not affect search, so this is the biggest difference.

That said, listing keywords is not the answer. Unnatural keyword stuffing violates Google Play’s guidelines and risks penalties. What matters is to place related keywords in natural sentences, in context.

Key points for setting it up:

• Natural writing comes first: keyword lists risk penalties
• Be especially mindful of the first half: put important keywords and feature explanations early
• Keyword density guideline: use the same keyword about 3 to 5 times in total
• Cover multiple angles: features, usage scenarios, FAQ, technical specifications and more

By covering the app overview, features, target users, usage scenarios, FAQ and technical specifications, you can include related keywords naturally while giving users useful information. The key is to keep keywords in mind while still writing text that users find natural and easy to understand.

Common Mistakes

Mistake 1: Duplicated keywords

Bad example (iOS): keyword field “workout log,workout,log,workout app” with the title “XX - Workout Log App”. “Workout” and “log” are duplicated and waste the 100 characters.

Better setup: fill the keyword field with words that don’t overlap with the title, such as “meal,calories,weight,exercise,menu,bodybuilding”.

Mistake 2: Listing keywords on Android

Bad example (Android full description): an unnatural list such as “workout,log,meal,calories,weight,management,gym,training,exercise…” is unreadable for users and risks violating Google Play’s guidelines.

Better setup: place keywords in natural sentences, such as “A fitness app that supports your daily workout logging, meal management and weight management. It works for gym workouts and for training at home…”

Mistake 3: Reusing iOS settings on Android

On iOS the description is not searchable, while on Android the full description is. Many people copy and paste the same settings without understanding this fundamental difference. You need an approach optimized for each store: on iOS, make full use of the 100-character keyword field; on Android, place keywords naturally within the 4,000-character full description.

Summary

The ASO strategy is fundamentally different for the App Store and Google Play.

On iOS (App Store), remember that only three fields are searchable: the 30-character title, the 30-character subtitle and the 100-character keyword field. The title matters most, followed by the subtitle and then the keyword field, and duplicated keywords are wasted (avoid overlap between the title, subtitle and keyword field as well).

On Android (Google Play), remember that the 30-character title and the 4,000-character full description affect search ranking. The title matters most, followed by the short description and then the full description. Place keywords in natural sentences in the full description (lists are not acceptable), and note that the 80-character short description also helps raise conversion.

On iOS “the title, subtitle and keyword field are searchable”, and on Android “the title and full description are searchable”. Understanding this basic difference is the starting point for ASO.

Start by reviewing your app’s current settings. In particular, check whether keywords are duplicated on iOS and whether keywords are placed naturally in the Android full description. Once the basics are in place, keep improving while regularly watching changes in search rankings and installs.