These are the Power levels as suggested by -cooldude- And I will rely on it from now on.
-> Civilian level
-> lieutenant level
-> lieutenant commander level
-> commander level
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■captain
-> captain level in Blue(Morgan&Buggy&Don Krieg)
-> captain level in HQ (Arlong&Kalifa&Kuro)
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■Rear admiral
-> Rear admiral level - Low Tier (Mr1&Fukurou&Kumadori&Blueno)
-> Rear admiral level - High Tier (Kaku&Jabra)
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■Vice admiral
-> Vice admiral level - Low Tier (Rob Lucci&Gecko Moria&Pacifista)
-> Vice admiral level - Middle Tier
-> Vice admiral level - High Tier (Kuma& Perespero)
-> pseudo admiral level (Doflamingo&Hancock&Queen&Jack&Smoothie&Cracker&Weevil)
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■Admiral
-> Admiral level - Low Tier (King&Katakuri)
-> Admiral level - Middle Tier (Oden&Marco&Fujitora&Ryokugyu)
-> Admiral level - High Tier (Kizaru&Aokiji&Benn Beckman)
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■Yonko
-> Yonko level - Low Tier (Akainu-Time Skip&Mihawk)
-> Yonko level - Middle Tier (OldWhitebeard&Big Mom&Kaido&Shanks)
-> Yonko level - High Tier (YoungWhitebeard&Roger&Garp)
->unknown level???-- IM???
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-> Civilian level=1~10
-> lieutenant level=10~20
-> lieutenant commander level =20~40
-> commander level=40~50
-> captain level in Blue=50~75
-> captain level in HQ=75~100
-> Rear admiral level - Low Tier=100~150
-> Rear admiral level - High Tier=150~200
-> Vice admiral level - Low Tier=200~400
-> Vice admiral level - Middle Tier=400~800
-> Vice admiral level - High Tier=800~1,400
-> pseudo admiral level =1,400~2,000
-> Admiral level - Low Tier=2,000~2,500
-> Admiral level - Middle Tier=2,500~3,000
-> Admiral level - High Tier=3,000~3,500
-> Yonko level - Low Tier=3,500~4,000
-> Yonko level - Middle Tier=4,000~4,500
-> Yonko level - High Tier=4,500~5,000
Do not rely too much on these numbers to determine the Power of the characters. These numbers are only to determine the level of growth of MC Power.
Sometimes a person can fight and defeat people of a higher level if they have a good strategy or have an advantage over their opponent (like when Luffy defeated Enel).
So don't rely on these numbers too much.