Power levels

 

The Radditz Saga

Radditz: 1,200
Piccolo: 408
Piccolo Special Beam Cannon (1st Try): 1,330
Piccolo Special Beam Cannon (2nd Try): 1,440
Goku: 416
Gohan: 1 - 1,370

The Vegeta Saga

Piccolo: 2,500
Piccolo (Powered Up): 3,400
Krillin: 1,673
Yamcha: 1,065
Tienshinhan: 1,834
Gohan: 2,000
Goku: 5,000 (Not Powered Up)
Goku: 9,000+(Powered Up)
Goku: 12,000 Kaioken x1
Goku: 16,000 Kaioken x2
Goku: 24,000 Kaioken x3
Goku: 45,000 Kaioken x4 Kamehameha
Nappa: 4,000
Vegeta: 8,000

The Freeza Saga

Krillin (Guru Power Up): 13,000
Gohan (Guru Power Up): 22,000
Kui: 18,000
Dadoria: 21,000
Zarbon: 22,000
Zarbon (Transformed): 26,000
Guldo: 435
Vegeta: 28,000
Jase: 29,000
Berter: 31,000
Racoome: 33,000
Captain Ginyu: 120,000
Vegeta (After Ginyu Force): 200,000
Goku: 550,000
Freeza (Form 1): 530,000
Freeza (Form 2): 700,000
Freeza (Form 3): 870,000
Freeza (Form 4): 1,200,000
Piccolo: 800,000
Goku (Max Power): 870,000
ssj Goku: 1,500,000
Cyber Freeza: 2,500,000
Trunks: 4,000,000

The Cell Saga

ssj Goku: 4,500,000
ssj Trunks: 4,500,000
ssj Vegeta: 4,700,000
Piccolo: 2,000,000
Gohan: 1,500,000
Andoid 16: 6,500,000
Android 17: 6,000,000
Android 18: 6,000,000
Android 19: 1,000,000
Piccolo fused Kami: 9,000,000
Vegeta (After Spirit of Time Training): 11,000,000
Trunks (After Spirit of Time Training): 15,000,000
Cell: 8,000,000
Cell (After absorbing Android 17): 18,000,000
Perfect Cell: 25,000,000
[Cell Game]
Piccolo: 16,000,000
Trunks: 17,500,000
Vegeta: 17,000,000
ssj Gohan: 9,500,000
ssj Goku: 25,000,000
ssj2 Gohan: 27,000,000
Super Perfect Cell: 27,000,000

Buu Saga

Piccolo: 28,000,000
Gohan: 29,000,000
Vegeta: 34,000,000
Goku: 34,500,000
Trunks: 14,000,000
Goten: 13,500,000
Android 18: 11,000,000
Kaioshin: 17,000,000
Kibit: 16,000,000
Yam: 30,000,000
Supopo: 30,000,000
Dabura: 33,000,000
Fat Buu: 38,000,000
Vegeta (Max): 36,000,000
ssj3 Gokou: 37,500,000
Majin Buu: 39,000,000
Gotenks: 29,000,000
ssj Gotenks: 38,000,000
ssj3 Gotenks: 41,000,000
Majin Buu + Gotenks: 42,000,000
Gohan's Zet Sword: 36,000,000
Kaioshin Gohan: 43,000,000
Buu + Piccolo + Gotenks + Gohan: 45,000,000
Vegetto: 50,000,000
Super Buu: 45,500,000

Power Levels and Powering Up
Power levels are hard to explain. It is not just strength, but the ability to fight. While training with Gohan, Goku told Gohan that they had to train in other ways(they were just exercising). If they were to continue training like that, they would become strong and muscular, but slow. Speed seems to be very important in most battles fought in the Dragon Ball world. So, there are many factors in saying what someone's power level is, and thats probably why they stopped using the term power levels. Now raising power levels is something different. It is more then just flexing muscles and screaming. I suppose it almost charging their mind (although that is a very awkward way of putting it). After they power up, they are physically stronger and faster, and have faster reflexes. Occasionally, powering up to extremely high levels seems to somehow affect gravity. Clouds and waves may form, or craters around the powerful person. A force or intense wind is also present when charging. It is strong enough to blow people off their feet in some occasions. Sometimes the pupils in the eyes of a Saiyan temporarily disappear, although I've only seen it happen once or twice.