Some of you may recall the massive Typhoon Vongfong or Typhoon 19 in Japan passing straight across the country a couple weeks ago. The typhoon is said to have had an amazing minimum atmospheric pressure of 900 hectopascals (26.58inHg) at one point.

If you’re anything like us, we were left looking at those figures in awe of how much we don’t remember from our high school science classes. Luckily there’s an easier way to visualize the effect Typhoon 19 had on the air pressure thanks to this video on YouTube featuring an experiment that uses a scale everyone can understand: a bag of potato chips.

The video was said to have been made on a JVCEverio camcorder set to time-lapse mode for every 40 seconds over a 33-hour period from October 11 to October 12. During this time Typhoon 19 made its approach and passed over Okinawa.

A single bag of Calbee Potato Chips Lightly Salted Flavor with 10 percent added chips was place on a table along with a clock and ruler behind it. At the beginning of the video we can see the bag measures 5.7cm.

Then as time marches on the atmospheric pressure begins to drop. This allows the flavor pressure of the potato chips to push further outwards thus causing the bag to swell. At its peak, the bag reaches a thickness of 6.4cm.

Therefore, we can calculate the maximum atmospheric pressure change over Okinawa as 0.7 Calbees (700mClb). According to a report by MyNavi News based on information from, the atmospheric pressure at about 9:00am on 12 October, a couple of hours before the bag reached maximum thickness, was 935hPa.

So, we can assume a rough conversion for Calbees to hPa and inHg to be:

Of course, more experimentation with more accurate data will be needed to refine this constant. Nevertheless, this should suffice when you are stuck talking to people who refuse to abandon those stodgy old units based on poisonous metals or dead French guys.

Source: YouTube – Itomai, Karapaia, MyNavi News (Japanese)