Accessible Task Completion Time

Time to complete an accessible task (minutes)

In ISO 9241-110, usability comes down to effectiveness, efficiency and satisfaction. When you want to measure efficiency, Time on Task (ToT) is the metric people reach for. Field studies keep finding the same thing: users with disabilities tend to spend somewhere between 2× to 3× as long as users without them. A rough starting estimate is ToT ≈ steps × 30s × accessibility_factor.

WCAG 2.1 SC 2.2.1 Timing Adjustable says any time limit has to be stretchable to at least 10× the default, or turned off altogether. At the AAA level, SC 2.2.3 drops timing constraints for content that isn’t real-time. Brazil’s eMAG benchmarks land at ≤ 2 min for a simple form and ≤ 10 min for something more involved.

Applications

Think usability testing reports, accessibility audits, SLAs for government services, tightening up an e-commerce checkout, and inclusive design KPIs. Collect the numbers through moderated sessions with people who actually use assistive technology — screen readers, switches, eye trackers.

FAQ

How do I baseline ToT? Start with a small pilot — 5 non-disabled users is enough to fix a median. Then run the same task with assistive-technology users and look at how the ratios compare.

Are session timeouts allowed? They are, with conditions. The user has to get a warning at least 20 seconds before the session expires, and extending it should take one simple action (SC 2.2.1).

What counts as “complete”? Count it as done only when the user reaches the success state on their own. Anything partial, or where a facilitator stepped in, gets logged on its own line.