How Many Meters Are In A Door

You're standing in the hardware store aisle, tape measure in hand, staring at a stack of pre-hung doors. The label says 2040 x 820. Plus, or maybe it says 80 x 32. Your brain does that quick, panicked calculation: wait, which one is meters? Which one is inches? Is that the rough opening or the actual slab?

Yeah. Been there.

The short answer: a standard interior door in most of the world is 2.On top of that, 00 meters wide. But "standard" is a dangerous word in construction. Also, 04 meters tall** and 0. Because of that, 92 meters wide. Still, 82 to 0. 90 to 1.Exterior doors tend to run 2.But 10 meters tall and **0. Let's break down what actually exists out there, why the numbers differ, and how to avoid ordering the wrong size.

What Is a Standard Door Size in Meters

Most countries that use the metric system — which is almost all of them — have settled on a handful of common door dimensions. Think about it: the logic isn't arbitrary. It comes from manufacturing efficiency, building code minimums, and the simple fact that humans need to fit through the opening.

Interior doors

In Europe, Australia, New Zealand, and much of Asia, the most common interior door slab measures 2040 mm × 820 mm (2.Which means 04 m × 0. 82 m). You'll also see 2040 × 720, 2040 × 920, and occasionally 2100 × 800 or 2100 × 900 depending on the manufacturer.

The height almost always clusters around 2.04 or 2.10 meters. Now, the width varies more — 620, 720, 820, 920 mm are the typical increments. These are slab* dimensions. The frame adds roughly 50–70 mm to the height and 60–80 mm to the width for the rough opening.

Exterior doors

Front doors, patio doors, and garage entry doors run taller and wider. Here's the thing — 2100 × 900 mm is the baseline for a single exterior door in many markets. Double doors? 6–1.Each leaf is usually 800–900 mm wide, giving a total clear opening of 1.2100 × 1000 mm is common for accessible entries. 8 meters.

Garage doors are a different beast entirely. A single-car garage door typically spans 2.4 to 2.But 7 meters wide by 2. 1 to 2.4 meters high. Double garage doors run 4.8 to 5.5 meters wide.

The North American exception

If you're in the US or Canada, you're dealing with inches masquerading as metric. A "32-inch door" is 813 mm. Practically speaking, a "36-inch door" is 914 mm. Height is usually 80 inches (2032 mm). Day to day, the industry labels* them in inches even when the packaging shows metric conversions. So when you see "2040 × 820" on a box at a big-box store in Toronto, it's because the manufacturer rounded 80 × 32 to the nearest clean metric number — not because it's a true metric-standard door.

Why It Matters: Rough Opening vs. Slab vs. Frame

Here's where people get burned. Three different measurements, three different numbers.

Slab size is the door panel itself. No frame, no hinges, no jamb. This is what the label on the box usually states.

Frame size (or "outside frame dimension") includes the jambs and head. Add roughly 50–60 mm to the height and 60–80 mm to the width of the slab.

Rough opening is the hole in the wall framing. It needs to be larger than the frame to allow for shimming, leveling, and squaring. Typical clearance: 10–15 mm per side, 15–20 mm at the top. So a 2040 × 820 mm slab needs a rough opening of roughly 2100–2110 mm tall × 900–920 mm wide.

Miss this distinction and you either can't get the frame in the hole, or you've got gaps you can't shim out. I've seen both. Neither is fun.

How to Measure for a Replacement Door

Replacing a slab in an existing frame? Measure the slab*, not the frame. Three numbers matter:

Height — measure both left and right edges. Old frames warp. Take the smaller number.
Width — measure top, middle, bottom. Again, use the smallest.
Thickness — 35 mm, 40 mm, 44 mm are common. Hinge mortises and latch bore locations depend on this.

Write them down. Take a photo. Don't trust memory.

For a full pre-hung unit in new construction or a gut reno, measure the rough opening. In real terms, diagonals too — if they're not equal, the opening is out of square. Width at top, middle, bottom. Height at left, center, right. That's fixable, but you need to know before the door shows up on a truck.

Common Mistakes (And How They Happen)

Confusing nominal with actual. A "900 mm door" might be 864 mm actual slab width. The 900 refers to the rough opening or an old imperial equivalent. Always check the spec sheet for actual slab dimensions*.

Forgetting flooring. You measure the rough opening before the finished floor goes in. Then the tile, hardwood, or carpet adds 8–20 mm. Suddenly your 2040 mm door drags. Either order a shorter door or specify the undercut at the factory.

Continue exploring with our guides on how many electrons can 3p hold and what is square root of 52.

Assuming all 2040 doors are the same. Hinge locations, lock bore height, backset — these vary by manufacturer. A door from Brand A won't necessarily fit Brand B's frame without mortise adjustments. If you're mixing brands, you're making extra work.

Ignoring swing and handing. Left-hand inswing vs. right-hand outswing changes hinge placement and lock prep. It's not just "which way it opens." Get it wrong and the door hits the light switch, the toilet, or the wall.

Ordering by "standard" without verifying. Just because 2040 × 820 is common doesn't mean your* opening matches. Older homes, custom builds, and renovations often have non-standard sizes. Measure. Every. Time.

Regional Variations Worth Knowing

Europe (EN standards)

Germany, France, the Nordics — they follow DIN 18101 / EN 14351-1. Now, frame adds ~60 mm height, ~70 mm width. Common sizes: 1985 × 610, 1985 × 735, 1985 × 860, 1985 × 985 mm (slab). Rough opening adds another ~20 mm per side.

UK

Metricated but still tied to imperial roots. "Metric 726" = 1981 × 726 mm slab (

the imperial 2'6" × 6'6" it replaced). Standard set: 1981 × 610/686/762/838 mm. Fire doors at FD30 are 1981 × 762 or 838 mm minimum under current regs.

North America

Imperial dominates residential: 6'8" × 2'6", 2'8", 2'10", 3'0" (2032 × 762, 813, 864, 914 mm). Taller 8'0" (2438 mm) options exist for newer construction. Here's the thing — 1-3/8" (35 mm) interior thickness, 1-3/4" (44 mm) exterior. Rough openings are slab + 2" width, slab + 2-1/2" height.

Australia / New Zealand

AS/NZS 2688 sets the standard. Common slabs: 2040 × 520, 620, 720, 770, 820, 870, 920 mm. That's why heights also come in 1980, 2040, and 2340 mm. Frames are typically 35 or 40 mm thick, with reveal depths around 30–35 mm.

Japan

Shorter standards reflect ceiling heights and body dimensions. Practically speaking, slabs often 1900 or 2000 mm tall × 650, 750, 850, 900 mm wide. Sliding doors (fusuma, shōji) use different modules entirely.

Adjustments and Tolerances

No opening is perfectly square. No slab is perfectly flat. Plan for shimming — usually 3–5 mm on the hinge side, occasionally more opposite the latch if the frame is twisted. Foam-in-place expanding sealants forgive more gaps than rigid packers, but don't rely on foam to fix a badly out-of-square frame.

Floors rarely finish exactly where the plans said. That's why undercut (the gap under the door) varies: 8 mm for carpet, 5 mm for tile with underlayment, 12–15 mm for supply air grilles or accessibility thresholds.

Hinges need reinforcement in hollow-core slabs. Think about it: without a solid block or a specially molded door, screws strip out within a season. Solid-core or laminated-veneer-lumber-core doors hold fasteners, but cost more and weigh more.

Fire and Acoustic Ratings

In commercial work, door schedules aren't just about size — they're about performance*. The frame needs matching fire rating. In practice, a 2040 × 820 FD30 door in the UK must have intumescent seals, fire-rated hinges, and a self-closing device. The certificate belongs on file.

Acoustic doors (STC 35, 40, 45+) use denser cores, perimeter gaskets, and drop seals at the bottom. In real terms, size tolerances stay the same; weight goes up. Plan for heavier hinges and stronger frames.

Where to Find Specs Without Guesswork

Manufacturer datasheets (always check the revision date)
National standards (DIN, BS, ANSI, AS/NZS)
The door schedule from the architect or designer
Physical measurement of a known-good existing door
Your supplier's technical line — use it, that's what it's for

A Note on Custom

When standard sizes don't fit — and sometimes they won't, especially in renovations — custom is the answer, not a compromise. Worth adding: lead times run 4–8 weeks for most custom orders. Cost increases 30–60% over stock. But the alternative is trimming a slab on site, which voids warranties and ruins finishes.

Final thought: The boring measurements are the ones that matter most. A door that looks beautiful but drags on the carpet, won't latch, or won't fit the frame isn't a door — it's a very expensive piece of wood. Measure twice. Order once. And when the spec sheet says 2040 × 820, verify it actually means 2040 × 820 before you sign the delivery slip.