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Manufacturer flex ratings are not exact, industry-standardized values. Nor can this guide be an exact assessment of them, but it should give you an idea of the relationship among flexes. In the end, you’ll do your own flex tests, remembering that in a warm ski shop you should be able to squat downward, flexing the boot forward without being thrust too far to the rear.
Flex ratings, from stiffest to softest:
150–140 Ridiculously stiff. For elite male racers.
130–120 Still a cinder block. For heavyweight and/or aggressive expert men, elite female racers
110–100 Sturdy but manageable. For typical high-expert guys; heavyweight intermediate men; most aggressive expert women
90–80 Moderate and comfort-oriented. For intermediate men; lightweight/nonaggressive expert men; junior racers; expert teens; female experts
70–60 Soft and ultra-comfortable. For novice men; novice/intermediate women; kids