Guard pay is very complicated. But in general, you can take your gross and divide it by 30. That's what you get in the guard for an active duty day or for one UTA period. You could do the same thing with your net after taxes to find out your take home pay.
A "drill pay" pay period is 4 hours. You do 4 "UTA's" on a drill weekend. You get paid 4 days pay for working two days. You'd be taking home around $600 if you are Captain over 8.
An FTP, which you get for flying, is the same as a UTA for pay purposes -- a 4 hour period. Heavy drivers can do 2 FTP's on one sortie if it is over 4 hours. You get 48 FTP's per year, with no more than 16 in a quarter, and I believe no more than 6 (maybe 8) in one month. You are bound by this 48 limit by law -- you can't ask for more. So you get 48 FTP's and 48 UTA's a year. That's 96 pay periods for double pay.
Then there are "Active Duty" days. These can be AT's (Annual Training) -- you are guaranteed about 15. They can be "Mandays" -- I call these gifts from the active duty Air Force -- normally funded by other sources. All of these are 1 for 1, i.e., 1 AT = 1/30th of your active duty pay.
There are more... PT's, etc. Some are active duty, some are inactive duty. Unless your unit tells you otherwise, you can only bank on 96 FTP's/UTA's and your 15 AT's. I would consider that your "minimum" for the year. Keep in mind that since you can front load your FTP's, times could get lean at the end of the year when you run out. Actually, this can happen each quarter if you front load the quarter.
So can you "trough" and make it? Lots of guys do -- but it takes a serious change in lifestyle and/or outside employment. I ask guys up front if they intend to trough before hiring them. You should tell your unit leadership truthfully what your plans are -- otherwise you could end up on the short end of the money stick. They will tell you what the outlook is for extra pay days so you can plan accordingly.
I advise guys jumping for AD to the ANG to have a BUCKET of cash in savings. You might not get paid anything for a couple of months, then when the check shows up, mama might have sticker shock. "Where is the rest of it?" Yikes.
Then there are the "temp" jobs. Temp AGR (Active Guard/Reserve) is identical to being on active duty sans bonus. Temp Tech is technician or civil service. A young captain can be lured into the Tech because it equals what a senior major or young L/C makes. As a technician, you also get FTP's and UTA's. You only get 12 FTP's a quarter or 36/year, since they know you are getting some flying done in technician status. Being a temp tech or temp AGR is a great way to bridge the gap to the airlines or other employment. You should ask up front if these might be available to you. Regardless, have your bucket ready -- you still may see significant pay delays.
Get ready to work. If you have an airline job, you still have to do your drill weekends and FTP's. Airline guys in my squadron work their butts off. 17 days at SWA, plus commutes, plus 6 days minimum at the guard equates to 4 or 5 days off a month. Senior SWA guys, and with other carriers pre-911, give away trips and get more time off -- but very few aren't watching the calendar waiting for 20 years military so they can hang it up.
Let me know if I just generated more questions.
-Elvis