Tablet tests with low vision users: Adjustability of text size

11. June 2014

We have tested five tablets with low vision users to see which one offers the best handling when you need to enlarge or modify the display of content.

An important aspect here is ability to adjust the default text size. Low vision users may not need to use the additional zoom function (available under accessibility settings) if text sizes could be adjusted throughout.

The tablets tested

We have tested the following five tablets (German version) with low vision users:

  • ASUS Memopad (Android 4.2.2, Asus-Skin)
  • Sony Xperia Tablet (Android 4.2.2, Xperia UI-Skin)
  • Samsung Galaxy Tab Pro (Android 4.2.2, TouchWiz-Skin)
  • Apple iPad 4 (iOS 7.1)
  • Windows Surface Pro 2 (Windows 8.1)

In all cases, text sizes reported here are not given as advertised by the tablet, but were measured in points with a physical typometer overimposed onto the display. Measurements are accurate with a margin of error of about 0.5 points.

With regard to the adjustability of text sizes, there are significant differences between these five tablets. The iPad 4 and Samsung's Galaxy Tab Pro offer larger text sizes than the competition.

Text size adjustments on the system level

All tablets tested offer system level settings for changing the text size. The problem is that these changes are usually not sufficient for low vision users. Often, mere text scaling does not offer large enough text. But even when a modest increase in size would be sufficient, the problem remains that the system level settings affect only some text elements. Other elements do not scale at all.

Home screens

The labels below the home screen's app icons are rather small on all tablets tested and are not affected at all by system level text size settings. Low vision users have to go by icon shape, color and position or use the built-in zoom function to read labels.

System settings

The Samsung tablet offers the largest default text size in the system settings - we measured 13 pt using a typometer. Users of the Sony tablet have to make do with 12 pt, Asus tablet users with 11 pt. On the iPad 4, text in the settings measures just 9.5 pt, but it can be rendered in bold to improve legibility (via Accessibilty > Bold text).

Dynamic text size

Only the Samsung tablet and the iPad have system-wide dynamic text size settings. However, these do not affect all text elements in apps. Windows 8 has display settings for Standard and Smaller - and Standard is already very small with 8 pt. "Smalller" leads to a tiny text size of 5 pt.

The other two Android tablets offer the standard (and somewhat confusing) Google approach of a linked text size setting at two places, either under Display > Font size (Small/ Normal / Large/ Huge) or under Accessibility > Large text (this has the same effect as setting the Font sitze under Display to "Huge"). When selecting Large  Text (or the equivalent font size = Huge) the text grows to just 10 pt, which is far from being huge – but certainly bigger than the default size of 8 pt at the setting Normal, and larger than on the Surface tablet (7 pt bzw. 8 pt) or the iPad (9.5 pt, bold).

Effect of text size settings on mail app elements

Our user tasks involved checking a mail for meeting details and replying to the sender. We used the default mail app that comes preinstalled on the respective tablet. Looking at text resizing in the different mail apps, the result is sobering: in none of the tablets tested, setting the system text size affected all important text elements in the apps.

On the Samsung tablet as well as on the Surface pro and the iPad, it is at least possible to additionally crank up the text size in the mail app settings, but this equally does not affect all text elements. Important elements like the subject and the sender are usually unaffected by the settings and do not scale like the body text.

In all mail apps tested, the mail body text can be additionally scaled up by using the pinch zoom gesture familiar from browsers. However, only on the Android tablets this will lead to a dynamic reflow of the mail text - not so on the Surface pro and the iPad.

Here are the results in detail:

Asus Memo Pad (Android 4.2.2, Asus-Skin)

Asus tablet: Mail app

Abb. 1. Asus Memo Pad ME302. Most text elements in the Asus mail app scale via the system-wide setting of "Huge text": the mail body text grows from 9 pt to 11 pt, mails listed in the inbox from 8 pt / 7 pt to 11 pt / 9 pt). Subject remains unchanged with 8 pt. In the screenshot the mail body text has been additionally scaled up via pinch zoom (it reflows when doing so). The icon controls for replying, forwarding etc. are very similar to those of the Google Android default mail app and are without fixed or pop-up labels.

Sony Xperia Tablet Z (Android 4.2.2, Xperia UI)

Sony tablet: Mail app

Abb. 2. Sony Xperia Tablet Z SGP321. Like on the Asus tablet, the sony tablet will allow increasing the main body text only via pinch zoom (and properly reflows when doing so). Mails in the inbox, sender and subject of the selected mail remain unchanged. In contrast to the Asus mail app, important controls are also labelled on the Sony.

Samsung Galaxy Tab Pro (Android 4.2.2, TouchWiz)

Samsung tablet: mail app

Abb. 3. Samsung Galaxy Tab Pro T525. That Samsung's TouchWiz skin deviates from the stock Android interface brings advantages to low vision users here. The default mail app allows to crank up the mail text size to a maximum of 22 pts. The screenshot shows the mail text without further scaling via pinch zoom. The sender text element in the inbox is also scaled up (and truncated), not so the subject line of mails in the inbox. System-wide text size settings only affect the text in the "New mail" edit window: 14 pt (at the setting "Very large" )instead of 9 pt (at the setting "Normal size").

Apple iPad 4 (iOS 7.1)

iPad: Mail App

Abb. 4. Apple iPad 4 MD513FD/A. On the iPad, choosing maximum text size in the system settings affects both the display of received mails as well as the "New mail" edit window, and is quite large with 24 pt. Subject is also rendered scaled-up – Sender and mails in the inbox remain unscaled but are easier to read than on the Asus and Sony tablets when choosing the iPad's "Bold text" setting. Pinch zoom on the body text works but does not lead to a dynamic reflow of text.

Microsoft Surface Pro 2 (Windows 8.1)

Surface pro: Mail app

Abb. 5: Microsoft Surface pro 2. The Surface tablet has the inverse behaviour compared to the iPad: Text size settings in the mail app affect Sender and Subject as well as the "Edit new mail" text which can be cranked up to 19 pt but do not affect the text of mails received - arguably the most important element.


Regarding the quality of text size adjustment, the iPad 4 and the Samsung Galaxy Tab pro clearly beat the other three tablets. It should be noted that test results are somewhat tentative in that we focused on the system level and the default mail app which show skin-specific differences. Future accessibility tests of other apps will include text size adjustability, so we intend to update / revise this article as more data becomes available.

Checking the text adjustment function is of course just one aspect of our comparative tablet test. Separate articles cover the zoom magnification function and usability problems faced by low vision users.