Blink Free Photos Calculator
Calculate the probability of getting a blink-free group photo based on the Ig Nobel Prize-winning formula. Find how many shots you need for 99% confidence with our free online tool.
About This Calculator
The Blink Free Photos Calculator helps photographers, families, and event organizers determine how many group photos they need to take for a guaranteed blink-free shot. Based on the Ig Nobel Prize-winning research by CSIRO photographer Nic Svenson and physicist Dr. Piers Barnes, this tool applies real statistical modeling to the universal problem of someone blinking in every group photo.
The calculator uses the formula P = (1 - f × t)^n where f is the blink frequency per second (10/minute in good light, 15/minute in bad light), t is the average blink duration (0.25 seconds), and n is the number of people. The probability that at least one person blinks is 1 - P. To find how many photos give you 99% confidence of a good shot, we use T = log(0.01) / log(1 - P) and round up.
For example, a group of 5 people in good light has about an 80.8% chance of a blink-free single photo. To be 99% sure, you need 3 shots. In bad light (blink frequency rises to 15/min), the same group drops to about 73.3% per shot, requiring 4 photos for 99% confidence.
How It Works
The science behind the calculation assumes blinks are random and independent — one person's blink does not affect another's. With an average blink lasting 250 milliseconds and a typical rate of 10 blinks per minute in good conditions, each person has a 1-in-24 chance of blinking during a 1/60-second exposure. Raising this probability to the power of the group size gives the chance that no one blinks.
Regional Notes
Global: The blink frequency and duration are universal human physiology constants, applicable worldwide. The formula works the same in any country or lighting condition.
Frequently Asked Questions
How does the Blink Free Photo Calculator work?
The calculator uses the formula developed by Nic Svenson and Dr. Piers Barnes, which won an Ig Nobel Prize. It calculates the probability that no one blinks in a group photo based on blink frequency (10 blinks/min in good light, 15 in bad light), blink duration (0.25 seconds), and the number of people. It then determines how many photos you need to take for a 99% chance of getting at least one blink-free shot.
How many photos should I take for a group of 5 people?
For a group of 5 people in good light, you have about an 80.8% chance of a blink-free photo in a single shot. To be 99% sure of getting a good photo, you need to take about 3 photos. In bad light (harsh sun), the probability drops and you may need more shots.
What is the formula for blink-free photos?
The formula is P = (1 - f × t)^n where f is blink frequency (10/min in good light), t is blink duration (0.25s), and n is the number of people. For 99% confidence, the number of photos needed is T = log(0.01) / log(1 - P). This formula won the Ig Nobel Prize for its creators.
Is this calculator free to use?
Yes, it is completely free to use with no registration or hidden charges. You can share your results via the URL which saves your inputs.
Why does light quality affect blink-free photos?
In bad light conditions like harsh midday sun or bright studio lights, people tend to blink more frequently — around 15 times per minute instead of 10. This higher blink frequency reduces the probability of capturing a blink-free photo, so you may need more attempts.
What is the Ig Nobel Prize connection?
Nic Svenson, a CSIRO photographer, was frustrated with subjects blinking in group photos. She asked physicist Dr. Piers Barnes to calculate the probability. Their work won the 2006 Ig Nobel Prize for mathematics, awarded for achievements that make people laugh then think.
What tips can help avoid blinking in photos?
Ask subjects to close their eyes completely and open them on the count of three. Alternatively, ask them to blink on purpose on 'two' so their eyes are fresh on 'three'. Relaxing, breathing, and thinking of something pleasant also helps reduce involuntary blinking.
Does this work for any camera or phone?
Yes, the calculator works for any camera setup. The formula depends on blink duration (~250ms) which is longer than typical shutter speeds. Whether you use a DSLR, mirrorless, or smartphone, the same blink statistics apply.