Why autocomplete matters
Mobile typing is slow and error-prone, so choosing a query after a few letters saves real effort; as Bast and Weber (2006) put it, type less, find more. Autocomplete helps users who cannot spell a term and previews what exists. It must update instantly, so latency matters. See mobile search UX.
How many, in what order
More options mean slower choices (Hick's law; Hick, 1952). Moran (2018) recommends ten or fewer, fewer on mobile. Eye tracking shows users focus on top items (Hofmann et al., 2014), so rank the likeliest first (Cai & de Rijke, 2016). Bold the appended part, not the typed part, so differences read quickly.
Mobile and accessibility
Make rows thumb-sized (Parhi et al., 2006; touch target size) and keep them above the keyboard. Typo-correcting suggestions and a 'clear recent searches' button help. On the web, follow the ARIA combobox pattern (W3C, n.d.) with aria-expanded and arrow-key navigation.
FAQ
- How many suggestions?
- Usually 5–8 on mobile so the keyboard does not hide them.
- Should typed letters be bold?
- Usually highlight the suggested remainder instead, so differences stand out.
Sources reviewed: 2026-10-27
References
- Moran, K. (2018, May 20). Site search suggestions. Nielsen Norman Group. Guidelines on number, highlighting and keyboard use.
- Bast, H., & Weber, I. (2006). Type less, find more: Fast autocompletion search with a succinct index. In Proceedings of the 29th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (pp. 364–371). ACM. Fast autocompletion indexing.
- Cai, F., & de Rijke, M. (2016). A survey of query auto completion in information retrieval. Foundations and Trends in Information Retrieval, 10(4), 273–363. Survey of query auto-completion ranking.
- Hofmann, K., Mitra, B., Radlinski, F., & Shokouhi, M. (2014). An eye-tracking study of user interactions with query auto completion. In Proceedings of the 23rd ACM International Conference on Information and Knowledge Management (pp. 549–558). ACM. Users focus on top suggestions.
- Hick, W. E. (1952). On the rate of gain of information. Quarterly Journal of Experimental Psychology, 4(1), 11–26. More choices, longer decisions.
- Parhi, P., Karlson, A. K., & Bederson, B. B. (2006). Target size study for one-handed thumb use on small touchscreen devices. In Proceedings of MobileHCI 2006 (pp. 203–210). ACM. Thumb target sizes for suggestion rows.
- World Wide Web Consortium. (n.d.). Combobox pattern. ARIA Authoring Practices Guide. Roles and keyboard behaviour for autocomplete.