Recently we’ve been hit by several hail storms in the Colorado front range – after digging around for a ruler after one storm, John pulled out his Digikey PCB Ruler and posted some hail photos on Facebook and Twitter. Folks really reacted to the photos, but more so the cool PCB ruler than the hail itself. That got us thinking and a few weeks later the hail ruler landed in our store!

The hail ruler is a multipurpose measuring tool that is designed to specially measure hail, but will find many other uses around your lab/home. In this post we’ll go over all of the hail rulers features. Be sure to head over to the swag store and pick a few up!

Inside Measurement


The hail ruler is specifically designed to measure irregular objects in two axes. The gold plated circuit traces mark standard measurements in millimeters and fractional inches. The drill hole at the origin makes measuring anything with a ragged corner easy and accurate! The all square corners with the scale even make it possible to de-warp an image for better 2D measurement capability!

The back side of the ruler has the National Weather Service size standards for “colloquial” hail sizes or pea, dime, nickel, quarter, half-dollar, walnut, gold ball, hen egg, and tennis ball sized hail. The tick marks for these sizes are along both inner edges of the ruler with the labels on one side only.

Depth Measurement

On the back side of the ruler with the colloquial hail sizes, there are imperial and metric scales along the outside edges of the ruler. These scales are referenced from the end of the ruler, not the center so you can measure depth of snow, hail, or just about anything else.



Other Features

The ruler also has a couple of other handy features:

Reported by: The white area on each side of the ruler allow you to write in your name or Twitter handle to tag your reports and make sure the ruler makes it back to you should you lose it!

Lanyard attachment: The large hole on the corner is just right to attach a lanyard for when you’re in the field or to hang it on a peg in your house so you always know where the ruler is.

White balance: Use the white logo areas to easily white balance your photos in post processing for color correctness in any lighting situation.

Severe criteria: On the inches scale of the ruler the National Weather Service severe and significant severe criteria are marked at one and two inches respectively.

Finally, this ruler isn’t just for the weather obsessed – it’s a handy tool in the workshop or even for the field geologist. If you want to take a photo with a size reference, you’ll want a hail ruler in your bag!


John Leeman
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