Sizing question

I’m planning to knit a hoodie sweater for a 5 year old. She is thinner and longer than the average child, so I was planning to adjust the pattern to suit a smaller chest with longer sleeves and body length. Does anyone have any experience with this type of change? Do you have any ideas about how to figure the finished size of the garment relative to the actual size of the child. Eg. Her chest is 22 inches. Should the finished garment measure 6 or 8 inches more than that?
Thanks for your help.

If you can, measure a sweater or shirt that fits her well. Then you’ll know how much ‘ease’ to put into it for a good fit.

I agree with Ingrid-that’s the best way to determine what size will be a good fit. However, if you are unable to do that, I would say 6 " of ease is a comfortable amount of ease for a child. That’s enough for plenty of freedom of movement.

That said, if the sweater is to be worn over another shirt, I would give it more ease-in that case 8" would be a good amount.

Good luck with the sweater!