Hole size and thread for toggle bolts and toggle wings, and hole size for hollow-wall (molly) anchors and plastic anchors — where two anchor makers agree. No load ratings: those come from the maker of the anchor.
A hollow-wall anchor holds by spreading behind the wall, so the hole has to be the right size: too big and it spins or pulls through, too small and it won’t go in or set. A toggle bolt needs a hole much larger than the bolt, because the folded wings pass through it; a molly and a plastic anchor go in a hole their own size. Pick the anchor for the wall and the job first (see Choosing the Right Anchor), then drill to this chart. For concrete and masonry anchors see Concrete Anchor Sizes.
Loads come from the maker
No load figures on this chart. What a hollow-wall anchor holds depends on the wall — drywall, plaster, paneling or block, its thickness and its condition — and on the anchor itself, and each maker tests and publishes its own anchors, with different results. Use the rating on the package or in the maker’s published data for that exact anchor and your wall.
Overhead and life-safety: never hang anything overhead or anything people depend on (grab bars, handrails, fixtures over people) on a hollow-wall anchor without the maker’s rating for that use; when in doubt, fasten into the framing.
| Type | How it holds | What it’s for | Hole |
|---|---|---|---|
| Toggle bolt | A machine screw and spring-loaded wings; the wings fold to pass through the hole and open behind the wall | Hollow block, wallboard, plaster and plywood | Much larger than the bolt — it has to pass the folded wings |
| Hollow-wall anchor (molly) | A slotted metal sleeve; tightening the screw draws the sleeve up into legs behind the wall | Hollow walls; the anchor’s length goes by the wall’s thickness | Sized by the anchor |
| Plastic anchor | A plastic sleeve a sheet metal or wood screw spreads as it is driven | A screw in concrete, block, brick or a hollow wall; light duty; not overhead | Sized by the screws it takes |
| Bolt size | Hole (wallboard) | Bolt thread |
|---|---|---|
| 3/16″ | 1/2″ | — |
| 1/4″ | — | 1/4″-20 |
| 3/8″ | 7/8″ | 3/8″-16 |
| 1/2″ | 1-1/4″ | 1/2″-13 |
| Anchor size | Hole |
|---|---|
| 1/8″ | 5/16″ |
| Screw size | Hole |
|---|---|
| #6–#8 | 3/16″ |
| #10–#12 | 1/4″ |
Drilling and setting
Drill the hole the chart gives for your anchor — or the size printed on the package where the chart has a dash.
Toggle bolts: the wings fold back to pass through the hole and spring open behind the wall, which is why the hole is so much larger than the bolt. Toggle bolts are used in hollow block, wallboard, plaster and plywood.
Hollow-wall anchors (molly) are made in lengths for the wall’s thickness — pick the length for your wall from the package. Tightening the screw draws the sleeve up behind the wall, or set it with a setting tool (puller).
Plastic anchors take a sheet metal or wood screw in the size range they are named for. They are not recommended overhead or where holding values are critical.
Not on this chart: Toggler / SnapToggle channels, plastic and poly toggles, self-drilling drywall anchors and drive anchors — each is one maker’s own design; follow the size and the instructions on its package.
Quick answers
- What size hole for a 3/16 toggle bolt?
- A 1/2″ hole in wallboard — the makers we checked agree. The hole has to pass the folded wings, so it is much larger than the bolt.
- What size hole for a 1/4 toggle bolt?
- The makers we checked print different hole sizes for a 1/4″ toggle, so use the size printed on your package. The bolt is 1/4″-20.
- What size hole for a 1/8 toggle bolt?
- The makers we checked print different hole sizes for a 1/8″ toggle (and name its thread differently), so use the size printed on your package.
- What size drill bit for a 1/8 molly (hollow-wall anchor)?
- A 5/16″ bit — the makers we checked agree for 1/8″ anchors of every length. Pick the length for your wall’s thickness from the package.
- What size hole for a plastic wall anchor?
- A plastic anchor for #6–#8 screws takes a 3/16″ hole and one for #10–#12 screws a 1/4″ hole (two makers agree).
- How much weight can a toggle bolt or drywall anchor hold?
- There is no one number: it depends on the wall (drywall, plaster, block), its thickness and condition, and the anchor, and each maker publishes its own values. Use the rating on the package or the maker’s data for that exact anchor and wall — and never hang anything overhead or life-safety on a hollow-wall anchor without the maker’s rating for that use.