how fast is a blink of an eye

A blink of an eye is extremely fast: most blinks take about 100–400 milliseconds, meaning roughly one‑tenth to four‑tenths of a second.

What “blink of an eye” really means

When people say something happens “in the blink of an eye,” they’re talking about the duration of a complete blink: eyelid down and back up again.

Researchers measuring human blinking find:

• Typical blink duration: about 100–400 milliseconds (0.1–0.4 seconds).

• Everyday rule of thumb: many popular science and eye‑care sources round this to “about a tenth of a second” for a quick, clean number.

• Blink frequency: around 15–20 blinks per minute for an average adult, which adds up to roughly 15,000–20,000 blinks per day when awake.

So in real‑life terms, you can easily blink two or three times within a single one‑second tick of a wall clock.

How “fast” is that in motion terms?

Speed here is a bit different from, say, a car’s speed, because we’re mostly talking about time, not distance traveled.

However, high‑speed camera studies that track eyelid movement give some numbers for how quickly the lid itself moves:

• Peak eyelid closing speed: roughly 200–250 millimetres per second (closing phase).

• Peak eyelid opening speed: somewhat slower, around 150 millimetres per second.

If you imagine your upper eyelid moving through just a few millimetres of distance in around a tenth to a few tenths of a second, that’s fast enough that the movement feels almost instantaneous.

Why our brains can “lose” that time

Even though a blink can take up to 0.4 seconds, you usually don’t notice that your vision disappeared for that moment.

Your brain effectively stitches together the images from before and after the blink so it feels seamless, which is part of why “blink of an eye” has become shorthand for something that seems to happen all at once.

A quick story‑style way to picture it

Imagine watching a digital clock change from 12:00:00 to 12:00:01.
You could comfortably blink two or three times in that single second, and to you it would feel like nothing important visually was “missing” in between—time just flowed on, almost as if your eyes never closed.

TL;DR: A blink of an eye lasts roughly 0.1–0.4 seconds, with the eyelid itself moving at peak speeds on the order of a few hundred millimetres per second—fast enough to feel instant, but still measurable.

Information gathered from public forums or data available on the internet and portrayed here.