I used a thermal camera to see how hot the Galaxy Z Fold 8 Ultra gets compared to the Galaxy S26 Ultra — here's what happened

Samsung's Galaxy Z Fold 8 Ultra lacks a built-in cooling system, unlike the Galaxy S26 Ultra, which features a vapor chamber to prevent heat build-up. Both phones share the same powerful Snapdragon 8 Elite Gen 5 for Galaxy chip, leading to curiosity about the heat generated during intense usage. To investigate this, a thermal camera, the Flir One Pro, was employed to monitor four devices - the Galaxy Z Fold 8 Ultra, Galaxy S26 Ultra, Galaxy Z Fold 7, and the iPhone 17 Pro Max - during a stress test using 3DMark's Solar Bay Extreme.

The results showed that the Galaxy S26 Ultra heated up the fastest, reaching around 30C (86F) within a minute, while the iPhone 17 Pro Max was close behind. Both foldable devices, the Z Fold 8 Ultra and Z Fold 7, took longer to heat up, with temperatures plateauing between 35C (95F) and 37C (99F) after 10 minutes of testing. Upon picking up the phones post-testing, it was evident that the S26 Ultra and iPhone felt noticeably hot, particularly around the camera bars.

Unfolding the phones revealed that the heat spread out rapidly from the top right corner, where the camera bar is located, and quickly covered the entire device. In contrast, the Galaxy S26 Ultra's heat concentrated in the top left corner, consistent with the placement of its vapor chamber. The iPhone 17 Pro Max followed a similar pattern, with heat accumulation near its raised camera bar.

The Galaxy Z Fold 8 Ultra, lacking an active cooling system, experienced heat spreading across the entire left side of the phone, potentially due to the hinge interfering with heat dissipation. While concentrating heat in a specific area may seem detrimental, if that area is devoid of major components, the heat spreading across the entire device could prove more detrimental in the long run.