How much joint compound do I need?
Joint compound — "drywall mud" — is estimated from the total drywall area you're finishing, because you tape every seam, coat every screw, and run the inside and outside corners across the whole job. A reliable rule of thumb:
About 1 gallon of all-purpose compound per 100 sq ft of drywall (taping + three coats).
That works out to a 4.5-gallon bucket (≈ 61.7 lb) per ~450–500 sq ft, or roughly 12 to 16 standard 4×8 sheets. Enter your area above and the calculator converts it to gallons, buckets, and tubs.
Finish level changes how much you use
The smoother the finish, the more mud you spread:
| Finish | Approx. coverage |
|---|---|
| Taped + 3 coats (typical) | ~100 sq ft/gal |
| Heavy fill / textured | ~110–130 sq ft/gal |
| Smooth skim coat | ~75–85 sq ft/gal |
| Level 5 (full skim) | ~60–75 sq ft/gal |
Set the coverage box to match your finish — lower coverage means more mud.
Ready-mix vs. setting-type ("hot mud")
- Ready-mix (tubs). Pre-mixed and DIY-friendly; all-purpose does taping and finishing, while a lighter "topping" mud sands easily for the final coat.
- Setting-type ("hot mud"). A powder you mix that hardens chemically in a set time (20, 45, 90 min). It shrinks less and lets you do several coats in a day — great for deep fills and first coats.
Types of joint compound
- All-purpose. The do-everything ready-mix — embeds tape and builds finish coats. The simplest choice for a whole job.
- Taping. A stronger compound made for embedding tape and first coats; harder to sand.
- Topping. Smooth and easy-sanding for the final coats — but too weak for taping.
- Lightweight all-purpose. Shrinks and weighs less and sands easily; a popular all-rounder.
- Setting-type ("hot mud"). A powder that hardens chemically in a set time — strong, low-shrink, and great for deep fills.
The coats (and finish levels)
A finished seam is built in passes: a tape (bedding) coat, a fill coat, and a finish coat, each wider and feathered out, then sanded. Drywall finish is rated Level 0–5: most walls are Level 4 (taped, three coats, screws covered), while Level 5 adds a full skim coat for surfaces under critical lighting or gloss paint — and uses noticeably more mud.
How much does joint compound cost?
A 4.5-gallon bucket of all-purpose compound runs about $14–$25 — far cheaper per gallon than 1-gallon tubs. The mud for an average room is inexpensive; the tape, sandpaper, and your time are the rest of the job.
Buying tips
- Buy the bucket. The 4.5-gallon bucket is far cheaper per gallon than 1-gallon tubs — get tubs only for small jobs or patches.
- Round up. Running out mid-coat is a hassle, and an opened bucket keeps for a while if sealed well.
- Don't forget the tape. A 500 sq ft job needs roughly a 250 ft roll of joint tape; the calculator covers the mud.