What Is the Biggest Phone in the World? Sizing Up the Largest Phones Ever Made

Fold it twice and it fits in a coat pocket; open it fully and it becomes a small tablet. The number that matters is that 10.0-inch diagonal — not height, width, or folded bulk. Mixing those up is how most “biggest phone” claims go wrong.

How Do You Measure “The Biggest Phone”?

Display diagonal decides the modern title, because screen size is what most people mean by “big.” Samsung’s buying guide lists the Galaxy Z Fold7 at 8.0 inches unfolded and the Galaxy S26 Ultra at 6.9 inches, both measured diagonally. The TriFold’s 10.0-inch main screen beats both.

Two caveats: the usable area is 9.9 inches once rounded corners and the camera opening are factored in, and “largest screen” isn’t “largest physical phone” — a device can carry a bigger display while folding smaller, which the TriFold’s dual-hinge design does. Neither measurement proves a record across every phone ever built, including prototypes and niche hybrids that never reached shelves.

Samsung Galaxy Z TriFold Specs

The TriFold pairs its 10.0-inch QXGA+ main display (2,160 × 1,584 pixels) with a 6.5-inch cover screen (2,520 × 1,080 pixels, up to 120Hz) for a normal phone experience when closed. Power comes from a customized Snapdragon 8 Elite Mobile Platform for Galaxy, and the rear camera is a 200-megapixel unit Samsung treats as a headline feature.

• Battery: 5,600mAh, with Samsung claiming up to 17 hours of video playback under its test conditions
• Thickness unfolded: about 3.9mm at the thinnest point, 4.2mm at the center screen
• Folded dimensions: 159.2 × 75.0 × 12.9mm, per Samsung’s published regional specs
• Storage: U.S. launch model ships unlocked with 512GB in Crafted Black
• Durability: IP48 — resistance, not waterproofing, and not protection from fine dust

That 12.9mm folded thickness is roughly half again as thick as a typical flagship slab phone — the real cost of a 10-inch screen in your pocket.

Biggest Phone Comparisons

The gap is real but not enormous — roughly two inches over Samsung’s largest foldable and three over its largest slab phone. Here’s the diagonal breakdown from Samsung’s published figures.

If a 10-inch foldable is more screen than you need, a standard foldable or large-slab phone is the middle ground — and to compare the biggest options before spending anything, our roundup of the biggest phones breaks down the trade-offs.

What Should You Know Before Buying?

Samsung’s U.S. availability announcement confirms the launch channel and pricing.

Verify the software at the counter: an independent PCMag review lists Android 16, but Samsung’s official pages don’t state the installed version. Handle the screen like the folding hardware it is — no excessive pressure, no sharp objects or debris near the dual-rail hinges, where a grain of grit is an expensive mistake.