On a Kai Planet he lifts 160 tons in the Manga, 40 tons a piece on each limb. This is just a basic approximation he can probably lift alot more, considering he was training his speed. Kai Planet = 100x earths gravity (king Kai knew goku had trained in 100x G before, so he had him train on 100x G Kai planet.). T = Tons G = Gravity 160T x 10G = 16,000 Tons

Super Saiyan transformation 50x strength increase,
16,000T x 50 = 800,000 Tons

SSJ2 usually regarded as a 4x strength increase, 800,000T x 4 = 3,200,000 Tons

SSJ3 also usually regared as a 4x strength increase, 3,200,000T x 4 = 12,800,000 Tons

SSJ4 strength increase 10x (Basically a minature Golden Oozaru), 12,800,000T x 10 = 128,000,000 Tons

If you now place this agains vegeta who trains at 500x earth gravity and above.
40T x 500G = 80,000 Tons

SSJ = 80,000 x 50 = 4,000,000 Tons

SSJ2 = 4,000,000 x 4 = 16,000,000 Tons

SSJ3 = 16,000,000 x 4 = 64,000,000 Tons

SSJ4 = 64,000,000 x 10 = 640,000,000 Tons

If you are talking about the very end of the Manga and Z, 10 years after above calculation. Base Goku is as strong as Kid Buu reincarnation, Which makes him as strong as his SSJ3 from 10 years ago.
Base Goku = 12,800,000 Tons
SSJ Goku = 640,000,000 Tons
SSJ2 Goku = 2,560,000,000 Tons Achieved Over Billion
SSJ3 Goku = 10,240,000,000 Tons. Achieved Over Billion

My calculation above are only approximations as Goku would increase in strength as he is training (Elder Kai gave him life which would last 1000 years).