Google Sheets has a limit of 5 million cells, but it's hard to know how much of your allowed space you've used.
In this tutorial, you'll use Apps Script to build a tool called Sheet Sizer, to measure the size of your Google Sheets!
It'll calculate the size of your Sheet and compare it to the 5 million cell limit in Google Sheets.
The full tutorial for Sheet Sizer is available here:
Sheet Sizer! Build A Tool To Measure Your Google Sheets Size With Apps Script!