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Device screen reference

iPhone 12 / 12 Pro screen size

Use this reference for iPhone 12 / 12 Pro CSS viewport width, physical resolution, DPR, diagonal size, PPI, and responsive testing notes.

iPhone 12 / 12 Pro viewport details

BrandApple
FamilyiPhone
TypePhone
CSS viewport390 × 844
Physical resolution1170 × 2532
Device pixel ratio3
Diagonal6.1 inches
Pixel density460 PPI
Aspect ratio19.5:9
Source labelManufacturer specs + iOS viewport reference
ConfidenceHigh
Testing note: Common older iPhone width still useful for QA coverage. Browser zoom, OS display scaling, address bars, toolbars, and orientation can change what JavaScript reports on a live webpage.

Visual comparison

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CSS viewport comparison

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Family · DPR · PPI

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Responsive testing notes

How to use this viewport reference

Use 390 × 844 as a practical starting point for testing iPhone 12 / 12 Pro layouts, then confirm the live viewport in the browser you are targeting.

Test CSS width

Start breakpoint checks around 390px, then resize slightly above and below that value.

Record DPR

A DPR of 3 affects image sharpness, canvas rendering, and screenshot interpretation.

Verify live values

Use the live checker because browser chrome, orientation, zoom, and OS scaling can change the usable area.

Source and update note

Reference values, not guarantees

This page is built from the ScreenMetricLab device viewport dataset. Values are normalized for practical QA and design use, but they should be verified on real devices or browser emulators before publishing critical layouts.

Record source: Physical display data should be verified against Apple specs; CSS viewport may differ by browser UI and zoom.

Updated 2026-06-26

Device references should be reviewed regularly as browsers, OS scaling, and hardware options change.

Use with live tools

Pair this page with the viewport checker, DPR checker, and screen resolution checker for better QA notes.

Frequently asked questions

What is the CSS viewport size for iPhone 12 / 12 Pro?

The reference CSS viewport for iPhone 12 / 12 Pro is 390 × 844. Live browser values can still change because of zoom, browser UI, OS display scaling, orientation, and responsive mode.

Is viewport size the same as screen resolution?

No. The physical resolution for this device is 1170 × 2532, while the CSS viewport is the layout area that websites normally use for responsive breakpoints.

Which value should I use for responsive testing?

Use the CSS viewport width first when checking breakpoints and layout bugs. Include DPR and physical resolution as extra context in QA reports.

Why can my live result be different from this reference?

Browser chrome, zoom, operating-system scaling, accessibility settings, split view, and orientation can all change the viewport reported by JavaScript.

Related tools

Use these tools to validate this device reference in a live browser.

What Is My Screen Size?

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Check your live screen resolution, viewport size, DPR, browser, OS, orientation, color depth, and refresh rate.

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Viewport Size Checker

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Measure the browser viewport and visual viewport that your website can use right now.

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Screen Resolution Checker

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Find the physical pixel grid reported by your current display and copy it for QA notes.

Check resolution →

DPR Checker

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See your device pixel ratio for responsive images, retina assets, and layout debugging.

Check DPR →

PPI Calculator

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Calculate pixel density from resolution and diagonal display size for phones, laptops, monitors, and TVs.

Calculate PPI →
View all related tools →

Related devices

More iPhone references

View family page →

iPhone 13 mini

375 × 812 CSS viewport · DPR 3

iPhone 14 Pro

393 × 852 CSS viewport · DPR 3

iPhone 15 / 15 Pro

393 × 852 CSS viewport · DPR 3