How do I darn a sock or a sweater?

Evidence grade: B2 — Practitioner rule of thumb Effort: Easy–Intermediate · 20–45 minutes · darning wool or matching thread, darning needle, darning mushroom (or tennis ball), scissors

Short answer: darning rebuilds knitted fabric thread by thread: anchor a grid of long stitches around the hole (the warp), then weave across them (the weft) until new fabric exists where the hole was. A darning mushroom or egg — any smooth curved form — holds the work taut while you sew.

What you need

Darning wool or thread matched to the garment (sock yarn for socks, matching weight for sweaters), a darning needle (long, blunt-tipped, large eye), scissors, and something smooth and curved to work over — a darning mushroom, a tennis ball, or even a jar lid [1][2].

The steps

1. Prepare. Turn the sock inside out if you like working from the wrong side (many darners do — the neater face ends up outside). Trim loose frayed ends, but don't cut away sound fabric. Stretch the hole smoothly over the mushroom and secure the fabric so it can't shift [1][2].

2. Lay the warp. Starting about half an inch beyond the hole in sound fabric, run long straight stitches back and forth across the hole, parallel to each other [2][3], leaving a tiny loop of thread at each turn (not pulled tight) — the loops allow for the fabric's stretch and for washing shrinkage (B2). Cover the hole plus a margin of sound knitting on all sides.

3. Weave the weft. With the same thread, weave perpendicular to the warp: over one, under the next, alternating each row so the rows interlock like plain cloth [2][3]. Keep the weaving snug but not tight — the darn should lie flat and flex with the knit, not pucker it.

4. Finish. When the hole is fully covered with new woven fabric extending into sound knitting all around, run the thread end into the surrounding stitches on the wrong side and trim [1].

For sweaters, the same technique applies on a larger scale; on thin spots that haven't holed yet, darn over the thinning area as reinforcement before it breaks through — the classic "darn it before it holes" rule [2].

The visible-mending alternative

Darning doesn't have to hide. Visible mending — darning in contrasting thread as a deliberate design feature — is a legitimate, even fashionable, choice, especially on sweaters [2]. Same technique, different thread. If the garment's value is sentimental rather than formal, consider making the repair part of its story.

⚠️ Stop rules

• Elastic that's dead (cuffs and sock tops with perished elastic): darning the fabric doesn't restore the stretch. Re-knit the cuff or retire the sock.
• Moth damage across a wide area: scattered holes in wool mean larvae may still be active. Freeze or heat-treat the garment and check the closet before investing hours in darning — otherwise you're repairing a buffet.
• Machine-knit fine gauge: very fine commercial knits are hard to darn invisibly by hand; a visible mend or a professional repair is the honest choice.
• Felted or matted wool: if the surrounding fabric has felted solid, the needle won't pass and the darn won't flex — the garment is past darning.

PPE and handling

• Ventilation: none required — no fumes. Good light and magnification on fine knits.

• Blunt darning needles exist for a reason: they slide between knit loops instead of splitting them.

• Don't pull the weft tight. A darn under tension puckers the first time it's worn.
• Match fiber to fiber when you can — wool darning wool behaves like the original in the wash.

Honest limits

• A darned heel or toe is thicker than the original knitting — it can feel lumpy in tight shoes. Some darners accept this; some relegate darned socks to boots.
• Darning restores fabric, not elasticity. The repaired area won't stretch like the knit around it.
• On dark socks, even matching thread shows under close inspection. Invisibility was never the promise — durability was.

Sources

1. NAPA Activities — "Darning" guide (opened and read) — https://napa-activities.co.uk/wp-content/uploads/2022/02/Darning.pdf — darning egg, mushroom, and gourd tools; turn the garment inside out; place the tool under the area; trim ragged edges; anchor stitches across the hole then perpendicular stitches; tie off.
2. LoveCrafts — "What is Darning? Fix Holes in Sweaters & Socks" (opened and read) — https://www.lovecrafts.com/en-gb/c/article/darning — darning egg and mushroom tools; weave-mend method: hole centered over the mushroom, warp as running stitches parallel to the existing weave, weft woven under/over the warp alternating each row; darning "can mend and even prevent holes" and "can be both invisible or visible".
3. Fabric Repair Café (Karma Coop) — "Repairing Holes, Rips and Tears in Fabric" (opened and read; squarespace-hosted PDF) — https://static1.squarespace.com/static/61b227835d47140cb5db1e81/t/683386d432a5af6cd5b67453/1748207317064/Repairing+holes+in+fabric.pdf — darning: warp as the running-stitch framework, weft woven over/under at right angles; darn socks inside out over a mushroom, tennis ball, or orange. (The ease-loop detail at warp turns is B2 practitioner guidance.)
4. The Spruce Crafts — "How to Darn a Sweater" — https://www.thesprucecrafts.com/how-to-darn-a-sweater-4156854 — dropped: fetch returned 403 (access denied); not openable, not citable. Its claims (reinforcing thin spots before they hole; visible mending) are confirmed by opened source [2] and re-cited there.

Repair Lab · Release 1 · Evidence last checked September 30, 2026 · A project of AOJEL