Touchscreen target size

28 Oct 2005 - 12:02pm
10 years ago
2 replies
1484 reads
Doug Anderson

Hi Norm, et al.,

I was browsing the contents of Ergonomics (I *must* get a life!) and was reminded of Norm Cox's inquiry on the above subject on 10Oct2005.

>From the list archives, his request was:
It's been a while since I've designed a touch screen interface, so... given a 15" LCD display and finger for stylus, what's the general consensus for the size of a discreet target? In the olden days on a CRT, it was typically about 20mm or 3/4". Given the reduction in paralax, improvements in touchscreen technologies, and such, what is a "standard" target size?

The article referenced below might be of interest (though perhaps too late to have any impact).

Doug Anderson
Mayo Clinic
Rochester, MN

Title: Standing at a kiosk: Effects of key size and spacing on touch screen numeric keypad performance and user preference
Authors: Herbert Colle; Keith Hiszem
Source: Ergonomics, Volume 47, Number 13, October 22, 2004, pp. 1406-1423(18)

Touch screen input keys compete with other information for limited screen space. The present study estimated the smallest key size that would not degrade performance or user satisfaction. Twenty participants used finger touches to enter one, four or 10 digits in a numeric keypad displayed on a capacitive touch screen, while standing in front of a touch screen kiosk. Key size (10, 15, 20, 25 mm square) and edge-to-edge key spacing (1, 3 mm) were factorially combined. Performance was evaluated with response time and errors, and user preferences were obtained. Spacing had no measurable effects. Entry times were longer and errors were higher for smaller key sizes, but no significant differences were found between key sizes of 20 and 25 mm. Participants also preferred 20 mm keys to smaller keys, and they were indifferent between 20 and 25 mm keys. Therefore, a key size of 20 mm was found to be sufficiently large for land-on key entry.
Articles that cite this article?
Keywords: Touch screens; Keypads; Key size; Key spacing; Kiosks; Keyboards; Human-computer interaction
Document Type: Research article
DOI: 10.1080/00140130410001724228


28 Oct 2005 - 2:01pm
Norm Cox (sent ...


Thanks for the reply (and, yes, you really should get out more!).

The article confirms what I've suspected all along as well regarding target size. I plan to do some visual "tricks" (small visual targets, but with proper active area and spacing) to keep my interface from looking to child-like with big buttons all over the screen. I'm working on a medical device with lots of data and settings, and would like to have the focus on the info, rather than large clunky buttons. But, hard to defend a smaller target design when the studies don't support it.

Thanks for the good reference.
Sent from the - discussion list 4 forum at

1 Nov 2005 - 8:37am
Stephen Mallett

I am working on Royal Navy project in the UK and we have the following target sizes :-

Push button 19mm square
with 3mm seperation between buttons.

This is to cope with 95 Percentile "Fat fingered" Navy personnel.

We have experimented with various suggestions, using stylus etc, but the need to touch the screen & see the affect overuled so we have huge buttons(compared to the rest of the worlds applications). If you need referenece material I can supply some. Mostly traced back University of Maryland Studies doen 15 years ago. Yes the Royal Navy are nearly into the 1990's !

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