How do i know if a deep cut needs stiches or i there an alternative?

Stitches?: After cleaning the wound, if the cut does not stay closed on its own or continues to bleed, then you likely need stiches. There are a variety of closures available such as the thread like material used to stitch the wound closed, staples, glue, steri-strips, etc. Each depends on the location and type of wound.

Need for care.: May need stitches if wound depth > 1/4”, wound edges are gaping or jagged or if fat / muscle is visibly extending from wound. If you can’t stop bleeding that requires medical intervention. See: http://www.mayoclinic.org/first-aid/first-aid-cuts/basics/art-20056711 Topical Skin adhesive or steri strips are possible alternatives.