How To Frame A 16×20 Poster: Glass, Mats, And Backing Explained

A 16×20 print fits a 16×20 frame directly, or sits behind a mat in a 20×24 frame — the mat overlaps the edges and keeps the poster off the glass.

Posters fade, buckle, and stick to glazing for one reason: the wrong materials against the paper. Pick the right frame size, the right backing, and the right tape, and a cheap print can look like it came from a gallery. Get it wrong and you’ll see wavy edges and washed-out color within a year.

This is the short version of what actually matters, based on archival framing practice and standard how-to guidance.

What Size Frame Do You Actually Need?

Measure the poster first — you want it to be exactly 16×20 inches edge to edge, not “close to.”

Then pick a setup:

• No mat (direct fit): a 16×20 frame.
• With a mat: a larger frame — the common pairing for a 16×20 print is a 20×24 frame, with a mat opening around 15.5 × 19.5 inches. The mat overlaps the print edges by roughly a quarter to a half inch, holding it flat.

If you’re framing a smaller print in a bigger frame — say an 11×14 in a 16×20 frame — the usual mat opening is 10.5 × 13.5 inches. Same logic, scaled down.

Glass Or Mat: What Protects The Poster Better?

A mat isn’t decoration; it’s the thing that keeps the poster from touching the glass. Contact between paper and glazing is what causes sticking, condensation damage, and visible surface marks over time.

If you skip the mat, you need spacers — small hidden strips that hold the glazing off the surface. Without them, direct-contact framing is a slow way to ruin a print.

For glazing material, UV plexiglass is the better choice for anything you care about: it filters ultraviolet light, which is what fades ink. Plain glass is cheaper and heavier, and sometimes costs more to ship. Either one has to be cleaned on both sides before you close the frame.

Which Backing And Tape Won’t Damage The Print?

Use acid-free materials throughout, and for anything valuable, step up to museum or conservation boards. This is the part most people regret skipping, because the damage is invisible for years and then it isn’t.

Attach the poster with acid-free tape at the top edge only. One hinge lets the paper expand and contract with humidity instead of rippling. Tape all four sides and the print will buckle.

If you’re still deciding on the frame itself, our roundup of tested 16×20 poster frame picks covers the options worth buying.

How Do You Assemble It Without Trapping Dust?

Lay everything out before you seal anything, and clean the glazing on both sides. Dust that gets closed inside a frame is essentially permanent without taking the whole thing apart again.

1. Measure and confirm the print is exactly 16×20 inches.
2. Clean both faces of the glass or acrylic; let it dry fully.
3. Place the poster on the backing board, or center it behind the mat opening.
4. Hinge the print at the top edge with acid-free tape only.
5. Stack glazing, mat, poster, and backing, then set them into the frame.
6. Close the frame and check for dust or stray fibers before the final seal.

When it’s done right, you’ll see flat paper, no visible gaps at the edges, and a clean, dust-free surface behind the glazing. For the detailed mat-cutting and hinging walkthroughs that shaped these steps, Adobe’s poster framing guide and Philip Hyde’s archival matting notes are solid further reading.

The habits that matter are small ones: acid-free materials, top-only hinging, spacers or a mat to keep paper off glass, and UV glazing if the piece will ever see daylight. Get those four right and a 16×20 poster will hold up for years instead of months.