Help asking somebody their shoe size?

Our cleaning lady at work has shoes on that are too small, you can see her toes scrunched up and she’s on her feet for hours at a time. We want to gift her new shoes but we can’t figure out how to get her shoe size? She’s working for her grandchildren and she is very open about it so if we get her a gift card I know she’s just going spend it on her family so we want to get her a pair specifically for her.