Shoe size compared to foot size for slipper

I am going to knit some old granny slippers for my daughters-in-law but I don’t know how to determine the length. I a shoe size is say 6, then what size do I knit the slipper? This has always been a mystery as to how people determine size when it is a gift. Thanks in advance

Usually a slipper is the same as shoe size. A size 6 is a woman’s small, I think.

I’ve found this guide to be indispensable.

I just saw that there’s a Slipper KAL/CAL on the KAL forum, so maybe they could help.

I have never had a problem with socks or slippers as gifts and my thoughts on this are easy:

For a size 6 - I knit the foot so it measures 6" from the heel to just before the toe decreasing. Then do the decreases, which are about 2" worth of knitting and you have a socks or slipper that fits perfectly.

Whatever size foot you are knitting for do that many inches from the heel to just before the toe decreasing. This has worked for me from a size 5 to a size 10, men or women.

Thanks for the tip. I am getting ready to make s,pipers for my daughter-in-law & grandkids.