I don't know that there's really a ratio of paste to dry, because the paste is a puree of roasted pepper and retains a lot of the fresh pepper flavor. Dry has a different character. I would consider the paste the more subtle ingredient and use it for recipes where that quality can be appreciated, using the powder for heavier recipes. The paste can also be concentrated to a greater or lesser degree by different makers. I would presume a small tube to be more concentrated than a large jar.
Here's what someone said about dosage:
"The proportion is usually 1 Tbs paste = 1 tsp powder if it is paprika of the sweet variety. As you usually add ¼ to ½ tsp paprika powder to a recipe, that means adding ¾ to 1½ tsp of paste." Half of that for the hot variety.
That ratio is the same as for fresh versus dried herbs, also.
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