Crewel or embroidery needles. Embroidery needles are the best needles for embroidery floss projects. You can identify these needles by their spacious eyes and pointed end. The large eye opening allows for easier threading and prevents the floss from breaking. Embroidery floss varies in size depending on the number of strands you use.
Best Needle Threaders for Embroidery - Final Thoughts. My final results told me that there is no perfect needle threader (at least out of the ones I tried). Since none of these can thread every needle, you could use a combination of needle threaders. OR try out my doubling up trick for when you need to thread 6 strands of floss that I show here.