iPhone Duo screen sizes: pixels, screenshots and app layout
Understand which dimensions belong in an image calculation—and which must be measured in your running app.
Three different measurements
A physical panel has a pixel grid. A submission screenshot has an export size. Your app receives a container with logical bounds and safe-area insets. Treat these as different inputs; dividing panel pixels by an assumed scale is not a runtime measurement.
Use the lab for a narrow, useful question
Our panel-ratio presets are 1878 × 2670 and 1398 × 2034 pixels, from the published specifications. The inner App Store screenshot size listed in our reference is 2007 × 2853. The lab answers how an image fits a rectangle; it cannot determine the space your app receives. Recheck the linked requirements before preparing submission assets.
Why a tall image loses content
For a source rectangle S and target T, fit uses the smaller width/height scale factor; fill uses the larger. Fill retains min(1, target area ÷ scaled source area). Fit occupies min(1, scaled source area ÷ target area). For example, a 100 × 200 image filling a 100 × 100 square retains half its area. The crop is centred in this lab.
Turn the calculation into a test
Pick a screen with edge controls. Compare its image in both target ratios, then run the app and inspect its actual bounds. Resize, show the keyboard and enlarge text. A clipped screenshot suggests a review target; a flexible native view might reflow correctly. Record the tested container, SDK and commit before calling it a result.
Sources and limits
Our calculations and proposed test steps are independent analysis. Follow the original documentation for SDK-specific behavior.