What is the difference between a running stitch, a backstitch and a slip stitch?

Four hand stitches compared on strength, visibility and what each is actually for, so you pick the right one for a repair.

Difficulty: beginner
Time: 15 min
Read: 3 min

Short answer

Running stitch is fast and weak — use it for tacking and gathering. Backstitch is the strong one, for seams. Slip stitch is the invisible one, for hems and closing gaps. Blanket stitch finishes a raw edge so it stops fraying.

Hand sewing has dozens of named stitches and four that do almost all the work. Knowing which is which is mostly about knowing what each one is bad at.

Four hand stitches compared

Step by step

Use a running stitch for anything temporary.In and out along the line, producing a dashed appearance. Quick, uses little thread, and easy to remove — which is exactly why it suits tacking two pieces together before proper sewing, and gathering fabric.
Do not use a running stitch on a seam that takes strain.Because the thread only sits on the surface for half its length, one break lets a long run pull free.
Use a backstitch for structural seams.Bring the needle up a stitch length ahead, then go back down where the previous stitch ended. The surface line is unbroken, which is why it is the strongest hand stitch and the closest to a machine seam.
Use a slip stitch where nothing should show.The needle travels inside the fold of the hem and catches only one or two threads of the outer fabric each time. Right for hems, linings, and closing the gap left when turning something through.
Use a blanket stitch on a raw edge.The thread loops over the edge itself, binding it. It stops fraying, it is decorative, and it is the traditional finish on blanket and felt edges.
Match stitch length to the fabric.Roughly 3 to 5mm on ordinary fabric. Shorter is stronger and slower; long stitches snag and give way.
Keep the tension consistent.Whichever stitch you choose, the thread should lie in the fabric rather than pull it. Even tension is what makes hand sewing look deliberate.

Tips

If it takes strain, backstitch. If it must not show, slip stitch. Everything else is detail.
Tack with a running stitch in a contrasting colour so you can see it to remove it.
A blanket stitch on a raw edge does the job that overlocking does on a machine.

Common mistakes

Using a running stitch on a load-bearing seam — Only half the thread length sits on each side of the fabric, so a single break allows a long section to pull open at once.
Using a backstitch on a hem — It shows as a solid line on the right side. Hems want a slip stitch, which is invisible because it catches almost none of the outer fabric.

If it doesn't work

Seam keeps opening

Cause: Running stitch used where strength is needed — Fix: Resew with a backstitch, and secure both ends into sound stitching.

Hem stitching visible

Cause: Catching too much of the outer fabric — Fix: Slip stitch, taking only one or two threads with each stitch.

Raw edge fraying inside the garment

Cause: No edge finish — Fix: Blanket stitch or zigzag the edge, or turn it under and stitch it down.

Questions people ask

Which stitch is strongest?

Backstitch, because the thread forms a continuous line on the surface and each stitch overlaps the last, so a single break does not unravel the seam.

What is a whip stitch?

A quick over-and-over stitch that binds two edges together, often used to close a stuffed toy or join two folded edges. It is faster than a slip stitch but visible.