How to Measure a Walk-In Cooler or Freezer Door

Ordering a replacement walk-in door comes down to a 10-minute measuring job. This guide shows you exactly what to measure, what to skip, and the mistakes that cause 90% of mis-ordered doors. You'll need a tape measure, a phone camera, and ideally a helper.

Prefer a shortcut? Our Find Your Door Size tool matches your measurements to the right door automatically. And if you'd rather have a person check your numbers, call 313-528-7888 or email photos to sales@eltcustomcoolers.com — we size doors every day.

Start here: which opening do you have?

We build five frame types, and each one is measured a little differently. Find yours below. Every face frame is 4.5" wide and 1.5" thick, except the bottom of a picture frame, which is 4". The jamb part is 0.5" thick.

• Replacing a door in a finished opening? You need a plug frame, which is face mount: it mounts on the face of the wall around the opening. Measure the finished opening, not the old door.
• New construction? You need a jamb frame, which is L-shaped. Measure the opening and the wall thickness, which sets the jamb size. The frame is built to leave a gap around it that you fill with spray foam after the door is installed.
• Replacing a flush door? You need a 1.5" or 2" jamb frame. Measure the net opening of the existing frame, and the bulk, which is the recess the flush door sits in. The new frame's net opening must match the existing one.
• Freezer? A picture plug frame is a four-sided face-mount frame with a 4" bottom.
• Picture jamb frame: a jamb on three sides, with the bottom as part of the face frame.
• Sandwich option: any frame type can have a second face frame on the inside of the wall, so the two frames sandwich the wall.
• Just need hardware or gaskets? Skip to Parts & Accessories.

Not sure which one you have? Send photos of the opening from inside and outside to sales@eltcustomcoolers.com or call 313-528-7888.

Step 1 — Measure the opening (not the old door)

Your door is built to the opening in your walk-in wall — measuring the old door slab instead of the opening is the #1 ordering mistake in this industry. Use the diagram above that matches your opening.

• Measure the width at three heights (top, middle, bottom) and the height at both sides.
• Use the smallest of each. Walk-in panels shift over the years; openings are rarely perfectly square.
• Check for square by measuring both diagonals — if they differ by more than about 1/2", tell us; we can compensate.
• Replacing a flush door? Measure both the net opening and the bulk.

Step 2 — Measure your wall (panel) thickness

Open the existing door and measure the wall's thickness at the opening edge — do not include the door frame itself. Most walk-in panels are 3.5" to 6" thick; 4" is the most common. On a jamb frame, this is your jamb size. It also matters if you order the sandwich option.

Step 3 — Determine your hinge side

Stand OUTSIDE the walk-in, facing the closed door. If the hinges are on your left, you need a left-hinge door. Hinges on your right, a right-hinge door. Every ELT swing door is available both ways.

If you're replacing an existing door and the layout works, simply match what you have.

Step 4 — Identify your frame type

• Plug frame (face mount) — mounts on the face of the wall around a finished opening. The standard choice for replacing a door.
• Jamb frame (L-shaped) — a 0.5" jamb leg lines the opening and the 4.5" face sits on the wall. The standard choice for new construction. The jamb size matches your wall thickness.
• 1.5" or 2" jamb frame — replaces a flush door. The jamb lines up with, and keeps, the net opening of the existing frame.
• Picture plug frame — a four-sided face-mount frame with a 4" bottom, for freezers.
• Picture jamb frame — a jamb on three sides, with the bottom as part of the face frame.
• Sandwich option — a second face frame on the inside of the wall, available with any frame type.
• Something else? If your opening doesn't look like any of the diagrams above, send us photos.

Step 5 — Cooler or freezer?

• Cooler (box stays above freezing, typically 35–41°F): standard door, no frame heat needed.
• Freezer (32°F and below): the door must have a heated frame — heater wire around the opening prevents the door from freezing shut — plus a heated vent port. If your current freezer door frosts over or freezes shut, its heater wire has likely failed; that alone is a common reason to replace.

Step 6 — Note your walk-in's brand (if known)

Check for a data plate on the door frame, inside wall panel, or above the door. Common brands we replace doors for: Kolpak, Amerikooler, Master-Bilt, Nor-Lake, US Cooler, Bally, American Panel, Imperial Brown, W.A. Brown. Any brand of walk-in can be fitted with an ELT prehung replacement door — the brand just helps us match frame details faster.

The 6 most common mistakes

1. Measuring the old door slab instead of the opening.
2. Measuring width at only one height (openings sag and bow).
3. Guessing the hinge side from inside the box — always determine it from outside.
4. Ignoring wall thickness — a 4" frame in a 6" wall won't seal.
5. Ordering a cooler door for a freezer box — the door will freeze shut without a heated frame.
6. Not mentioning raised or recessed floors, ramps, or obstructions within 8" of the opening.

Opening damaged or badly out of square?

It happens — forklifts, moisture, and 20-year-old panels take a toll. Photograph the opening from inside and outside, note your measurements, and send everything to sales@eltcustomcoolers.com. We build custom doors and frames to fit imperfect openings.

Measured? Here's what's next

• Match your measurements to a door →
• Shop cooler replacement doors →
• Shop freezer replacement doors →
• Request a quote for a custom size →

Questions at any step: 313-528-7888 — real people, in Detroit, who build these doors.