Earning Credits is the only way to increase your rank in Halo: Reach, but there are many, many ways to do this. One of the most reliable ways to earn Credits is to just play online matchmaking games as much as possible. You will be awarded for all sorts of things in matchmaking, from kills to medals. Another great way to earn Credits is to complete daily and weekly challenges. You'll can even see how many Credits you'll earn for each in the challenge menu. Finally, commendations are another great way to earn Credits and rank up. Check out your commendations menu and work towards the goals in all your campaign and matchmaking sessions. Earning a silver rank lands you a few thousand Credits!

Here are the Credit amounts you need to attain for each rank in Halo: Reach

• Recruit - 0 cR
• Private - 7,500 cR
• Corporal - 10,000 cR
• Corporal Grade 1 - 15,000 cR
• Sergeant - 20,000 cR
• Sergeant Grade 1 - 26,250 cR
• Sergeant Grade 2 - 32,500 cR
• Warrant Officer - 45,000 cR
• Warrant Officer Grade 1 - 78,000 cR
• Warrant Officer Grade 2 - 111,000 cR
• Warrant Officer Grade 3 - 144,000 cR
• Captain - 210,000 cR
• Captain Grade 1 - 233,000 cR
• Captain Grade 2 - 256,000 cR
• Captain Grade 3 - 279,000 cR
• Major - 325,000 cR
• Major Grade 1 - 350,000 cR
• Major Grade 2 - 375,000 cR
• Major Grade 3 - 400,000 cR
• Lt. Colonel - 450,000 cR
• Lt. Colonel Grade 1 - 480,000 cR
• Lt. Colonel Grade 2 - 510,000 cR
• Lt. Colonel Grade 3 - 540,000 cR
• Brigadier - 1,400,000 cR
• Brigadier Grade 1 - 1,520,000 cR
• Brigadier Grade 2 - 1,640,000 cR
• Brigadier Grade 3 - 1,760,000 cR
• General - 2,000,000 cR
• General Grade 1 - 2,200,000 cR
• General Grade 2 - 2,350,000 cR
• General Grade 3 - 2,500,000 cR
• General Grade 4 - 2,650,000 cR
• Field Marshall - 3,000,000 cR
• Hero - 3,700,000 cR
• Legend - 4,600,000 cR
• Mythic - 5,650,000 cR
• Noble - 7,000,000 cR
• Eclipse - 8,500,000 cR
• Nova - 11,000,000 cR
• Forerunner - 13,000,000 cR
• Reclaimer - 16,500,000 cR
• Inheritor - 20,000,000 cR