The Doherty threshold: under 400 ms, the user stays in the flow

Below a 400-millisecond response time, the user stays focused, engaged and productive. Above it, attention drops. This is the Doherty threshold.

Formulated by Walter Doherty at IBM in 1982, it establishes that when the machine responds in under 400 ms, a virtuous circle sets in: the user chains actions without a break. Speed is not just comfort, it is a driver of usage.

The principle

Beyond a few hundredths of a second of waiting, thought pauses. At 400 ms, the thread breaks: the user looks away, doubts, slows down. Below it, the interface seems to extend their intention without friction.

Perceived speed is a design topic

• Immediate feedback. A hover state, a click that reacts at once reassure, even if processing takes a moment.
• Skeletons and preloading. Showing structure before content reduces the felt wait.
• Optimistic UI. Displaying the likely result while the server confirms gives a sense of instant response.

Below 400 milliseconds, the machine follows thought. Above it, it holds thought back.

When you cross the threshold

When waiting is unavoidable, make it legible: progress indicator, estimate, an animation that occupies. An explained wait is far better tolerated than a frozen screen that makes people fear a crash.

In practice

Performance is not just a server matter: it is UX. Optimizing page weight, deferring the non-essential, caring for the first render, all of it directly serves engagement. A fast site is not a technical luxury, it is a condition of conversion.

Frequently asked questions

What is the Doherty threshold?

The finding that a response time under 400 ms keeps the user in a productive flow, while beyond it their attention and efficiency drop.

Do I really need to aim for 400 ms?

It is a benchmark, not an absolute rule. The idea: the faster the better, and below that threshold the experience changes in nature.

What if a task takes long?

Make the wait visible and understandable: immediate feedback, progress indicator, optimistic display. An explained wait is far easier to accept.

Florent DABERNAT · Art director and founder of IDSEED, based in Aix-en-Provence. I help my clients with branding, UX/UI and web, using a clear and documented method. Learn more ➞