TOS: (Fasa rulebook)
Recruit - 'Enterprise Star' (ES).
Enlisted 2nd Class - ES with slash underneath.
Enlisted 1st Class - ES with 2 slashes underneath.
Petty Officer 2nd Class - ES with chevron underneath.
Petty Officer 1st Class - ES with 2 chevrons underneath.
Chief Petty Officer - ES with chevron and rocker underneath.
Senior Chief Petty Officer - ES with chevron and 2 rockers underneath.
Master Chief Petty Officer - ES with chevron and 3 rockers underneath.
Warrant Officer - 1 silver broken stripe. 1cm wide.
Chief Warrant Officer - 1 silver stripe.
Ensign - No stripe. (officer stripes are 2cm wide)
Lt, j.g. - 1 gold broken stripe.
Lt - 1 gold stripe.
Lt Cmdr - 1 gold broken stripe above 1 gold stripe.
Cmdr - 2 gold stripes.
Capt - 1 gold broken stripe between 2 gold stripes.
Comdr - 3 gold stripes.
Adm - Thick shaded area between 2 gold stripes.
Movies: (D Schmidt's Line Officer Requirements)
Lt, j.g. - 1 silver pip with gold tip.
Lt - 2 silver pips with gold tip. Tips facing. 0.5cm apart.
Lt Cmdr - 1 gold bar in a silver cage.
Cmdr - 2 gold bars in a silver cage.
Capt/ Fleet Capt - 3 gold bars in a silver cage.
2 gold arrowheads on ends of Fleet Captain.
2 silver arrowheads on ends of Captain.
Comdr - 1 gold arrowhead on a bronze circle.
R Adm - 2 gold arrowheads on a bronze rectangle.
V Adm - 2 gold arrowheads on a bronze triangle.
Adm - 4 gold arrowheads on a bronze square.
Fleet Adm - 5 gold arrowheads on a gold pentagon.
TNG: The "pips" (the circles on the uniform collars) signify rank. A
hollow circle counts as a half circle:
0.5: Ensign, Junior Grade ?
1.0: Ensign
1.5: Lt., Junior Grade
2.0: Lt.
2.5: Lt. Commander
3.0: Commander
4.0: Captain
5.0: Commodore (from TNG Tech Manual)
There is almost certainly no such rank as "ensign, junior grade" in Starfleet, because there is none in the US Navy, which the Starfleet ranking system is otherwise impeccably modeled after. The "0.5" pip insignia was first spotted, apparently, in "The Drumhead", worn by Crewman Simon Tarses, who had not attended the Academy and therefore could not be an ensign. Subsequent inferences about this insignia can only be relied upon if one assumes that Miles O'Brien has never been a lieutenant, or indeed a commissioned officer, despite what Richard Arnold says (and despite a singular reference in "Where Silence Has Lease"). The current concensus is that the "half-pip" or hollow single circle must represent a non-commissioned rank to which O'Brien has been promoted. A good candidate is that of "Chief Warrant Officer" (again, despite what has been said before), which would be a promotion above "Chief Petty Officer" (from "Family"). Note that this also contradicts the trading cards. The "ensign junior grade" rank is a non-authoritative creation of Shane Johnson and is only used in his Starlog "TNG Technical Journal" (and, incorrectly, in Jeanne Dillard's DS9 novelization for "Emissary").
All the admirals shown on TNG have had two gold bars, one on each collar,
each with three gold pips:
_______
| |
| O O O |
|_______|
So perhaps gold bars with fewer pips would be used for Fleet Captains. We'll have to wait and see if they ever show up on future TNG episodes.
Deanna Troi's rank was given as "Lt Commander" in "Encounter at Farpoint" (the pilot episode) and occasionally on computer displays (e.g. "The Child"). She is introduced by Captain Jellico to some Cardassians as "Lieutenant Commander Troi". Also, in "Disaster", she has command on the bridge; O'Brien said that "Counselor Troi holds the rank of lieutenant commander". Since she's been back in uniform, she has been consistantly wearing 2.5 pips. In TNG's "Thine Own Self" Troi took the Bridge Officer's test and became a full Commander.
Wes was made an acting ensign by Picard in "Where No One Has Gone Before", then made full ensign in "Menage a Troi" and given a uniform.
O'Brien was addressed by Worf's father as "another chief petty officer" in "Family". He was referred to as "Lieutenant" by Riker in "Where Silence Has Lease" when Riker and Worf beam over to the fake Galaxy-class vessel (though this was before he had been given a name, so it could theoretically be a different character). The latest set of collector's cards has a card for O'Brien and gives his rank as Lt Jr Grade. They apparently decided to demote him for the episode "Realm of Fear" in order to allow Barclay to give orders to him. Richard Arnold (who still works for Paramount even though he lost his office when Roddenberry died) and the Script Consultant mentioned at a March 1993 Creation con in Minneapolis that O'Brien is a lieutenant. Forget his old pips, forget everything else--he is a lieutenant. Also, he was never a petty officer because Star Fleet does not have Petty Officers (ignoring "Family" for the moment). Keiko mentions in the 2nd or 3rd episode of DS9 "...but you would have to give up your promotion").
Riker was given a field promotion to Captain in "The Best of Both Worlds Part 2", but was back to being a commander in the next episode.