How much molding do I need for a picture frame?
A 16×20 frame in 2" molding takes about 8 1/2 feet of stock once the miters are allowed for. The arithmetic, plus lengths for every common frame size.
A 16" × 20" opening in 2" molding takes 20" and 24" pieces, long point to long point.
That is 8.4 linear feet of molding with 15% added for the offcuts the miters throw away. Buy a full stick — you cannot join a short one.
How that is worked out
- Each piece has to cover the opening plus the width of the molding at both ends, because a mitered corner is as long as the molding is wide: 16" + 2 × 2" = 20" at the long points.
- The same on the other axis gives 24".
- Two of each is 88", and the 15% allowance for offcuts brings it to 8.4 feet.
Molding needed, 2" wide frame stock
| Opening | Top and bottom | Sides | Outside size | Buy |
|---|---|---|---|---|
| 5" × 7" | 9" | 11" | 9" × 11" | 3.8 ft |
| 8" × 10" | 12" | 14" | 12" × 14" | 5.0 ft |
| 11" × 14" | 15" | 18" | 15" × 18" | 6.3 ft |
| 16" × 20" | 20" | 24" | 20" × 24" | 8.4 ft |
| 18" × 24" | 22" | 28" | 22" × 28" | 9.6 ft |
| 24" × 36" | 28" | 40" | 28" × 40" | 13.0 ft |
Worth knowing
- These are long-point lengths — the outside edge of the miter, which is the longest point on the piece. Cut to the long point and the short point takes care of itself.
- The opening is the glass or the artwork, not the frame. A rabbeted frame holds the glass a little inside that, so add about 1/8" to each dimension for slack — glass cut to the exact opening will not go in.
- Cut all four pieces before assembling any of them, and cut the pairs to each other rather than to a tape. Two pieces exactly the same length matter more than either being exactly right.
- Frame stock is sold by the linear foot and is expensive. The 15% allowance covers the offcuts, not a mistake — buy extra if this is the first frame in this profile.
Work out your own numbers
- Picture frame miter cuts
Cut lengths, long point to long point, for a rectangular mitered frame, and how much molding to buy.
- Miter angle calculator
The miter for baseboard, casing or chair rail at any corner angle — flat trim, so there's no bevel to set.
Related questions
- How do I work out frame molding length?
- For each side, take the opening dimension and add twice the width of the molding. That accounts for both mitered ends, because a 45° miter runs back exactly as far as the stock is wide. Then add about 15% over the four pieces for what the saw throws away between cuts.
- What size frame for a 16x20 print?
- The frame is named by the opening, so a 16×20 frame takes a 16×20 print. In 2" molding the finished outside size is 20" × 24". If you are matting the print, the mat's outside dimension is what has to match the opening, not the print.
- Do I measure a picture frame inside or outside?
- Inside — the opening — because that is what has to fit the artwork, and it is how frames are sold. The outside size follows from the opening plus twice the molding width. Both are in the table above, since the outside size is what has to fit the wall.