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 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

• Replacing an existing door? You'll measure the rough opening (the hole in the wall), not the old door. Existing openings are typically matched to a plug frame.
• Cutting a new opening? New openings are typically matched to a jamb frame. Measure the opening you plan to cut.
• Just need hardware or gaskets? Skip to Parts & Accessories.

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

The rough opening is the framed hole in your walk-in wall. Your replacement door is built to this opening — measuring the old door slab instead of the opening is the #1 ordering mistake in this industry.

• 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.
• Our prehung doors allow roughly 1" of rough-opening tolerance.

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. This determines the frame depth of your new door.

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 — the frame inserts into and fills the wall opening; the door overlaps the wall face. The standard choice for replacing a door in an existing opening.
• Jamb frame — the frame wraps the edges of the opening like a house door jamb. The standard choice for new openings.
• Picture frame / surface-mount (facing) frames — trim styles for special situations; if your current frame doesn't look like either diagram, 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 rough 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.