iPhone 18 Pro In-Depth Review: The 2nm A20 Chip Is the Real Star

If this were any other era, it would be called a classic "S-update." The iPhone 18 Pro is essentially an iPhone 17 Pro with a new chip, upgraded cameras, better battery life, and a few new colors to signal it's a new model. That sounds unremarkable — yet after a week with the device, MKBHD's conclusion was clear: this phone is seriously underrated.

Note: underrated, not underpriced. At $1,200, it's still expensive. But it deserves far more attention than it's getting. For two consecutive years, the Pro lineup has lived in the shadow of other models — last year it was the iPhone Air stealing the spotlight, this year it's the first-ever folding iPhone Duo. The flagship Pro hasn't launched a truly groundbreaking feature in over a decade, because the bold experiments go to other product lines. And yet the Pro remains the best iPhone Apple makes — and it's quietly getting better and better.

Camera System: Variable Aperture Now and in the Future

On the hardware side, the camera setup is nearly identical to last year's — the same triple-camera configuration from the 17 Pro: a 48MP main sensor, 48MP ultrawide, and 48MP 4x telephoto. The real new addition is the variable aperture lens on the main camera.

For almost the entire history of iPhone — and nearly every smartphone except Samsung — lenses have used a fixed aperture. The iPhone 18 Pro's main lens can open all the way to a new maximum of F1.48, and step down to F1.8, F2.8, and F4. Third-party apps reportedly support smooth, stepless adjustment.

So how much of a difference does it actually make? MKBHD is candid: on this generation, the effect is quite subtle. The depth-of-field difference between F1.48 and F4 is hard for most people to spot at a glance. He compares it to the difference between white balance at 4800K vs. 5400K, or shutter speed at 1/60 vs. 1/48 — these are Pro tools designed for creators who want finer control over their shots. The starburst effect produced by the six aperture blades when stopped down is exactly that kind of detail.

Why is this underrated? Because variable aperture pays off more with larger sensors. MKBHD has reviewed phones with one-inch sensors, and their naturally shallow depth of field makes close-up shots hard to nail — the entire subject often can't stay in focus, and autofocus tends to hunt. If variable aperture carries forward to the day when iPhone uses a significantly larger sensor, it will become a genuine game-changer rather than a footnote.

Apple has also finally added more granular manual controls to the Pro camera app — customizable arrangement of shutter speed, format, manual focus, and the long-awaited manual white balance. In MKBHD's view, these software-level upgrades improve the shooting experience more than any single piece of hardware. He also offered Apple two suggestions: provide a Rec.709 preview while recording Log video to aid exposure, and open up 8K 30fps recording sooner rather than later.

What is aperture, exactly? The aperture (f-number) determines the size of the lens opening. A smaller f-number means a wider opening, more light, and shallower depth of field. On traditional DSLRs and mirrorless cameras, variable aperture is standard — photographers stop down to achieve greater depth of field, reduce diffraction, or create starburst effects with the aperture blades. Smartphones, however, have been constrained by their tiny lens elements and have long relied on fixed apertures, simulating background blur through computational photography. Samsung's Galaxy S24 Ultra experimented with variable aperture but offered limited stops with modest gains. The iPhone 18 Pro extends the maximum aperture to F1.48 with multiple stop-down positions. The deeper significance: as sensor sizes grow, a fixed wide aperture produces an extremely shallow depth of field that becomes difficult to control. A variable aperture then becomes an essential mechanical component for wielding a large sensor — not just a marketing bullet point.

A20 Pro Chip: The 2nm Process Is the Real Story

This is the point MKBHD keeps returning to throughout the review. The 18 Pro and 18 Pro Max are powered by the new A20 Pro chip, which — alongside the simultaneously released M6 — adopts an all-new 2-nanometer process node.

The chip's value isn't visible in benchmarks or multitasking smoothness — every new iPhone is already fast enough; that's no longer a differentiator. What actually tells the story is that the A20 Pro simultaneously delivers greater performance and meaningfully longer battery life in the same chassis.

Typically, a chip generation offers one or the other: faster but not more efficient, or more efficient but not significantly faster. The 2nm process delivers both. The key is a structural change — Apple moved the DRAM that was previously stacked on top of the CPU to the side, freeing up space directly above the CPU for a vapor chamber three times larger, dramatically improving thermal management.

For most people, whether the chip reaches M1 or M2 levels of performance is irrelevant. But for heavy gamers or creators like MKBHD who spend hours shooting 4K video in the summer heat of New Jersey, the thermal gains from that oversized vapor chamber — combined with a connected mid-frame — are significant. Video exports and image processing are noticeably faster, the Neural Engine's compute has doubled, and even on-device Siri — which ran slowly on the iPhone 16 — is now snappy.

MKBHD is even excited about the next-generation MacBook Neo as a result — the current model uses a cut-down A18 Pro with 8GB of RAM, while the A20 Pro with 12GB RAM is essentially M1-class silicon. He also muses that this 2nm chip proves Moore's Law isn't dead — humanity is approaching transistors the size of individual atoms.

What does nanometer process mean? The nm figure refers to the characteristic feature size between transistors. A smaller number means more transistors can be packed into the same area. Going from 3nm to 2nm theoretically fits roughly 15–20% more transistors in the same footprint, operating at lower voltage to perform the same computation — meaning faster and more power-efficient. TSMC's 2nm node (N2) is among the first commercial processes to use Gate-All-Around (GAA) transistor architecture, replacing the older FinFET design, enabling more precise control of leakage current. This is the fundamental reason the A20 Pro can improve both performance and efficiency simultaneously — not simply by adding a bigger battery or a larger heatsink. Moore's Law predicts transistor density doubles roughly every two years; the industry has long worried about physical limits, but the mass production of 2nm shows that architectural innovation keeps the scaling roadmap alive. Silicon atoms are roughly 0.22nm in diameter, so there are still several process nodes of headroom before hitting true physical limits.

Battery Life and Charging: Efficiency Over Capacity

Apple markets the 18 Pro as having "the longest battery life ever," with figures like 36 hours of video playback and 30 hours of mixed use. MKBHD finds those numbers of limited practical value. What genuinely impressed him: the 18 Pro's battery life matches the previous-generation 17 Pro Max.

He primarily tested the smaller 18 Pro and found it consistently lasted a day and a half between charges — close to two days on lighter use — and this is under heavy conditions: high brightness, heavy photo and video capture, and two hours of CarPlay daily.

The key: the battery hasn't grown by much (roughly 3%). The gains come almost entirely from the efficiency improvements of the 2nm architecture, not from a physically larger or denser cell. MKBHD even speculates what would happen if Apple simultaneously adopted silicon carbon anode batteries.

Charging is a genuine step forward. With a 67W charger, the phone sustains around 45W of draw; five minutes of wired charging yields seven hours of video playback. The Pro Max's battery is roughly 10% larger than its predecessor. Interestingly, EU energy efficiency label requirements have revealed European capacity figures: Pro at 4,056mAh and Pro Max at 5,391mAh. US eSIM models are expected to be slightly higher, with the Pro Max around 5,500mAh.

What is a silicon carbon anode battery? It's a key direction for next-generation lithium batteries. Traditional lithium battery anodes are primarily graphite; silicon has roughly ten times the theoretical lithium storage capacity of graphite, but silicon expands by up to 300% during charge and discharge cycles, causing electrode cracking and failure. By combining silicon with carbon nanotubes or graphene, engineers can retain the high energy density advantage while suppressing the expansion. Android manufacturers including Xiaomi and vivo have already deployed silicon carbon anodes in flagship phones, achieving roughly 10–15% higher energy density without significantly increasing battery volume. Apple has not publicly adopted this technology in iPhone yet. MKBHD's speculation underscores the point: stack the efficiency gains of 2nm architecture on top of the capacity gains from silicon carbon anodes, and the ceiling on iPhone battery life would be considerably higher than where it sits today.

Design Details and Colors

There are a handful of other incremental updates: the new C2 modem also contributes to improved efficiency; and the Dynamic Island shrinks for the first time — Apple moved the infrared Face ID sensor from the center to the upper-left corner, hiding it beneath the display. The top of the screen can now accommodate three Live Activities instead of two. The implementation is remarkably clean — only under direct sunlight can you occasionally catch a faint circle in the upper-left corner.

On colors, MKBHD flatly called the new burgundy "ugly," but had warm words for glacier blue (a pale sky blue) and the matte black he's been using daily — though it picks up fingerprints more readily than expected.

Final Verdict: Exactly What You'd Expect, and Worth It

MKBHD's conclusion: this phone holds no surprises. The Pro lineup has been incrementally iterated for years, never taking risks. The 17 Pro was a relatively significant "Tick" update (new metal design, thicker body, larger battery, camera bump, 3,000-nit display, anti-reflective coating, and more), which makes this a very solid "Tock."

The 2nm chip shoulders the vast majority of this upgrade's weight, while the variable aperture camera reads more as a foundation being laid for the future. It's imperfect, expensive, and entirely predictable — but as MKBHD puts it, "meeting expectations" is itself a form of value.