Measure the water it took to fill ... Even if you use an online compression ratio calculator, it's important to understand the underlying math.

If your math skills are up to snuff ... measure the distance between two or more points on a map. To calculate smaller length measurements, use Side Meter on your phone.

In iOS 18, Apple has added a powerful new feature to your iPhone's Calculator app: Math Notes. This integration between Calculator and Notes offers a versatile tool for all your calculation needs.