Recommendations
A practical starting range for crab legs in the oven is 10-15 minutes at 175°C. This page is built to answer the cooking-time query fast without burying the useful part under a long recipe story.
Use the clock as guidance only and confirm an internal temperature of at least 74°C when that safety target applies.
The result usually shifts most with frozen vs thawed, covered/foil steaming, amount of water/steam, so treat the range as guidance rather than a guarantee.