MIPS stands for Multi-directional Impact Protection System, and it addresses a specific crash risk: rotational forces. When you hit the ground at an angle—which is how most cycling crashes happen—your head can twist inside the helmet, and that twisting motion can cause serious brain injuries. MIPS adds a low-friction layer between your head and the helmet liner that allows a small amount of sliding during impact, reducing rotational force by roughly 10-35%.
For most riders, MIPS is worth seeking out. It's the most widely tested and available rotational protection system, found on mid-range to premium helmets across road, mountain, and commuter categories. The tradeoffs are minor: it adds about 20-50 grams of weight and may feel slightly different against your head.
That said, a helmet without MIPS still meets safety certification standards—MIPS is an extra layer of protection, not a replacement for proper fit and basic certification.