What is the proper way to address NCOs in different branches?

Recruits, they address any marines, enlisted or otherwise as sir or ma'am. Once one becomes a marine they address by rank as any other branch. I guess recruits don't rate to even say ranks.

Army
E1- knucklehead
E2- private
E3- private
E4 - specialist or corporal
E5- Sargent
E6-- Sargent
E7 -Sargent
E8- Sargent or if first Sargent you better call him first Sargent "top" is only if you haven't pissed him off recently
E9-- Sargent major or command Sargent major , and you better get it right

I seldom had a lot of interaction with female sailors unless I was TAD to a shore facility. Those female Petty Officers I came to know never objected to being called Petty Officer (name) or by a slightly more familiar 'last name' used with discretion. Once you got above E-6 it was Chief, Senior Chief, or Master Chief regardless of sex. I watched an E-2 call a female E7 "Ms Chief" one time........charity forbids I describe the result. We were trained that the terms 'Sir' and 'Ma'am' were applied to Officers and civilians. I'm pretty sure you can never go wrong by addressing them by their rank/name. That may have changed since the days of sails and oars when I served.......*grin*

SSgt to MSgt in USAF should be addressed as Sergeant, SMSgt (E8) as Senior, CMSgt (E9) as Chief. First names are not proper anytime for addressing anyone that is senior to You. If there is a diamond shown with His or her stripes., You may address them as 1st Sergeant. A star within the Stripes an E9 would be Command Chief I don't find anything wrong with the use of the word Sir or Mam either, there is nothing that is not polite about that.

Its not a bad idea to learn about the rank structure of every service, I have done that a long time ago. That includes , Army, Air Force, Marines, Navy and Coast Guard for enlisted, NCO's Petty Officers, Warrant Officers and Commissioned Officers.

Funny I was at Camp Lejeune for joint task force training GunnySgt was given me the riot act for mud on my boots then another guy says hey that Barret you jump out of planes mate well the gunny didn't like the interruption when he addressed the other guy he was pissed before he could get two words out this guy says hey man bugger off before I put my boot in your arse then his friends showed up and the GunnySgt left I was dumbfounded asked who are you guys they said they were in the French foreign legion nobody outranks us I said OK then we went to the O club I said I can't go in they said you can tonight mate they were right good guy crazy as hell though

I am retired E-7 Army my response to and NCO would sergeant form the rank E-5 to E-7 E-8 first sgt E-9 sgt major not Sir.. that title is for commissioned officers..

In the Army, all sergeants are "sergeant" until they become a master sergeant/first sergeant or sergeant major/command sergeant major.
In the Marine Corps, you use the full rank, sergeant, staff sergeant, gunnery sergeant, master sergeant...
In the Navy, it's pretty officer or chief.
In the Air Force, "...hey Bob..." works just fine....

If you are not sure how to read their rank but they obviously have more rank than you then you should address them as sir or ma'am. They in turn should be professional enough to introduce themselves as Staff Sergeant Joe or Gunny Joe or Master Sergeant Joe. From that point on you should address them as that rank.

E-7 is Gunnery Sergeant, or Gunney if they allow it. Anytime I heard someone refer to any Army Sergeant as Sarge, they would be corrected (tactfully if they out ranked me) Airforce is Airman or Sergeant, bit when in doubt ask.

Don't call them Sir. That's only boot camp. The Corps use full rank. Sgt, Staff Sgt, Gunny,1st Sgt/ Master Sgt or Top and Sgt Maj/Master Gunns. When I left the Corps it was hard for me to call a Sgt 1st class just plain Sgt. Then I finally went USAF and it was pretty much what the person wanted to be called.

With the Air Force E5-E7 can be called Sgt. E8 is always full rank (SMSgt= Senior Master Sergeant) and E9 can be called Chief.

Recruits calls everyone sir/ma'am they haven't earned the title to call them by their ranks...

I was taught to call people Sir and Ma'am to people by my parents who were raised during the depression etc. It helped me call officers Sir or Ma'am very easily in my time in the USAF.

But when it came to enlisted, I tended to call folks "Airman XXXX" or "Sergeant XXXX" or "Chief XXXX" when it came be a Chief Master Sergeant in front of others.

I worked in a career field where I ended up working with other services from time to time.. same thing.. "private, sergeant, mister (in the case of warrant officers)" in the Army. Tried to do my best with the Marines, Navy, Coast Guard etc. Made a mistake once in front of a Gunnery Sergeant in the USMC who corrected me when I called him Sergeant as he preferred to be addressed as "Gunny". But I did not take the incident personally.. I just pressed on and got along just fine.

But there were times when I did not have to use titles in conversation, and I would revert to answering questions as "yes sir" etc.. But I never did it as a form of address and never had someone jump all over me for it.. It was just the way my parents taught me.. and to this day I still find myself doing it at times.

Gunnery Sergeant

I have never addressed any NCO as Sir or Ma'am, I would have been handed my heart on a plate. This is reserved for officers only. NCOs by rank and enlisted are by rank unless part of your team and then by name. Depending on Team: last name, or first name, or even nick name. Semper Fi!

Enlisted personnel, outside of basic training are NEVER referred to as Sir or Ma'am.
You address them by their rank. So an E7 in the corp will be addressed as Gunnery Sergeant, or for short, Gunnery. In the Navy? Chief.

You address them as you address NCO in the army which is by rank

I would address them by there Rank like SFC Smith or SGT doe and so and so on. SSG MARK A FRANZEN

If we don't know the rank, Sir or Ma'am is the go to. But we make it a point to address everyone by rank if they are enlisted. Now if we were on a more closer working relationship with them, we might call a GySgt a Gunny or a MSgt Top, or MGySgt Master Guns.

Now in the 2nd part of your question you mentioned recruits. Recruits do not rate to call anyone by their rank. Recruits will address everyone as Sir or Ma'am until they "earned" the privilege to address someone by rank.

You can never ever go wrong by respecting the rank, and addressing him/her by such! Nothing hard about it, you just simply respect the rank! End of discussion, in fact, this shouldn't even be a thread, because common sense should've kicked in before you asked the question. I'm just saying. Enjoy the thread! :-)