My recipe tries to stay true to the original, it's closer to J.O. or Wye River Red seasoning in it's flavor profile. I'm going to give 2 different measurements, one for a small batch and one for a large batch that you'll need to steam crabs.
Chesapeake Bay Seafood Seasoning
1T / 3C salt
1 1/2tsp / 1 1/2C black pepper
1tsp / 1C celery seed (bruised)
1tsp / 1C paprika
1/2tsp / 3T mustard powder
1/2tsp / 3T onion powder
1/4tsp / 1T garlic powder
1/4tsp / 1T cayenne pepper
Mix all the spices together until well blended. Allow to sit at least overnight for flavor to meld together before using. Keep in a tightly sealed container for up to 6 months.