I've been using a program to make charts on my iPad using an app that is no longer available, so even though it's still on my iPad, I've been looking at other options for how to make knitting charts. I work primarily with an iPad and with a Chromebook, so Windows software for charting isn't really an option and neither is a graphics program like Illustrator. I came across some articles like this one about how to use Excel to make charts. Well, I don't have Excel either, but I do have Google Sheets.
The first step was making the grid in Google Sheets into even squares. It turns out if you click on the box in the upper left hand corner you can manipulate the size of all the rows or columns at once. However, you are just doing it by eye. There was no way I found to specify how to change all the rows to a specific size at the same time.
Next problem, no special symbols menu in Google Sheets. I opened a regular Google Document and went to "Insert-- Special Characters..." and picked symbols for the common stitches I use in charts. I copied and pasted those in a row across the top of my grid paper spreadsheet. I can copy and paste them onto the squares as needed.
Here is a copy of what I did that you can use to get started. Just click on the link and the sheet will open up. You can make a copy to edit it.
So now I can more quickly make charts from written patterns because in a spreadsheet I can copy and paste repeats and rows and motifs. You can see an example below. This is a chart of the Pendants pattern from the Second Treasury of Knitting Patterns by Barbara Walker. You can see the little arrows I used to mark the beginning of the repeats. The charts could be transferred to a pattern by taking a screenshot and editing in a web based program like Pixlr.