How to convert from a knitting pattern?

[creekbottom]

Just a general question.  I see some great patterns on Pinterest only to find out that they are knitted, not crocheted.  

[Granny Square]

Short answer:  you don't, at least there's no formula like 3 purls=1 DC or something like that.  The size ratio of the stitches is all different, the way stitches behave, and so on.  It really requires a complete redesign.  There are a couple of crochet stitches that look a bit like knit stockinette -- straight slip stitch in the round looks like knitting (stockinette), but it's horizontal vs.vertical and bulky (doesn't drape like knitting).  Likewise the 'knit' stitch in Tunisian, it looks like stockinette (and goes in the 'right' direction) but it's comparatively bulky.

There is a technique called knooking, though.  It uses a crochet hook to actually, really knit.  So, you have to learn how to read a knit pattern and so on, the only difference you are using 1 hook with a string at the end vs. 2 needles; the string acts as the second knitting needle.  I already can knit, and there isn't an advantage for me (I find making stitches off a string is harder/fussier than making them off a needle).  But, it might be something to consider.  Walmart used to carriy knook hooks, made by Leisure Arts, they might still have them--might be worth a try.

A knit stitch is pretty much like a crochet slip stitch.  A purl is the same, but is made from back to front, instead of front to back.  Those and yarnovers are the building blocks of knitting, everything is built off of them.  Except, there are all sorts of ways to cast on and bind off which differ; I use a crochet hook to do both for the most part.  It's not hard, it's just different.  There are pluses and minuses for each craft.  

[magiccrochetfan]

if you like the cut and shape of a knit pattern, and if the knit pattern that has a good schematic, you could use the schematic to crochet the garment pieces.  Given the fabric differences as Granny Square described,  you would probably need to carefully consider your yarn/hook size and swatch  a lot to get the desired drapiness of the fabric.  but if you are willing to have a crocheted fabric instead of knit, and willing to work w/o a full pattern, it might be do-able.  it would be similar to using a sewing pattern to crochet something.

However there are also crochet versions of many knit things.  so for example if you are looking something like a knit cabled scarf, there are crochet cable patterns, with several new cabling techniques recently published in magazines.  

One other thought, since many things on pinterest are translated from other languages, many translations will say knit even if the item is crocheted as the original language only has one word for both.   And many sites that get linked to pinterest do not actually have patterns, they only have an attractive photo and a chart/diagram for a stitch pattern that is similar but not really the same, so the links themselves can be misleading.  

[redrosesdz]

Have you tried learning to knit? There's lots of crafters that do both. 

[Granny Square]

I should try this again, because I've forgotten the details and frogged the swatches, but a few years ago I tried to match knit stockinette worsted weight fabric to crochet - and ended up needing to go down to sock weight yarn.  Might of also worked with sport weight, but I didn't have any handy.  Part of the reason (my theory) is that knit stitches are 'incomplete' compared to crochet stitches.  Knit can unravel in both directions until it's bound off - on the last row.  Crochet stitches are bulkier because they are functionally a bound off in each stitch, so would compare to each knit stitch being combined with a bind off stitch.  Sorta.