Apple Watch Series 4 mockup

The LTPO OLED Retina display with Force Touch reaches 1000 nits brightness and comes in two sizes: 324 × 394 pixels with a 759 sq mm display area on the 40mm model, and 368 × 448 pixels with 977 sq mm on the 44mm model.^[2] For full-screen art, work in portrait at 324 × 394 pixels for the 40mm model or 368 × 448 pixels for the 44mm model, and keep important content away from the curved corners.^[1][2] The two sizes have almost the same proportions, so a file made at 368 × 448 can be scaled to fit either.^[2] The 44mm size has the same resolution as the 44mm Apple Watch Series 6.^[2][3]

Both sizes are 10.7mm deep: the 40mm case is 40mm high and 34mm wide, and the 44mm case is 44mm high and 38mm wide.^[2] Aluminum came in silver, gold and space gray, and stainless steel in silver, space black and a new gold.^[1] The back is black ceramic and sapphire crystal; over the display, aluminum models have Ion-X glass and stainless steel models have sapphire crystal.^[1][4]

On the side of the case, the Digital Crown sits above the microphone and the side button.^[5] Series 4 added haptic feedback to the Digital Crown and built electrodes into it: with the ECG app, users touch the Digital Crown and after 30 seconds receive a heart rhythm classification.^[1] GPS + Cellular models have a red ring on the Digital Crown.^[4]