The smritis classify sins into Mahapatakas, Upapatakas and also Jathibhramshakaras, Samkareekaranas, Apatreekaranas and Ashudhikaras.
The mahapatakas (great sins) are five in number.
1. Brahmahatya - killing of brahmin
The equivalent sins are lying about one's varna, giving false information causing somebody to be punished, false accusation against Guru.
2. Surapanam - drinking alcohol
The equivalent sins are to talk bad about vedas and also to forget the veda learned, being false witness, killing of friend, eating what is forbidden and at forbidden time.
3. Steyam - stealing from brahmin
The equivalent sins are stealing of treasure, children and women, horse, silver, land, diamond and jewels.
4.Gurutalpagamanam - illicit relation with the Guru's wife
The equivalent sins are illicit physical relation with sister, daughter, daughter-in-law, friend's wife and low cast women
5. Tatsamsarga - to interact with one who has performed the above sins,
The upapatakas (sub - sins)
1. Killing of cow.
2.Performing yajna for the forbidden cast
3. Having illicit relation with somebodyelse's wife
4. Selling or pleging oneself
5. Not taking care of guru and parents
6. Relinquishing vedic study
7. Not performing the agni rituals
8. Not taking care of the son
9.Younger brother marrying before the elder
10.To speak ill about the chastity of a girl
11. To make living out of lending money
12.To break vows
13.Selling of lake, garden, wife and son
14.Non performance of upanayanam at the proper time
15. Not helping one's relatives
16. Teaching for salary
17.Llearning by paying fee
18.Selling prohibited materials
20.Buiding dam etc.
21.Destroying trees and plants
24. Cutting tree for fuel
25. Cooking only for oneself
26.Eating forbidden food
27.Not performiong agnihotra
29.Not repaying debt (deva,pitru and manushya)
30.Learnig subjects that are against veda and smrutis.
31.Acting and dancing to entertain others.
32.Having relation with a woman who consumes alcohol
34.Lack of belief in life after death
35. Harassing brahmins
36. Smelling forbidden items such as alcohol
39. Killing of donkey, horse,camel,deer, elephant, sheep, fish, snake and buffalo
40. Receiving money from evil people
41.Commerce ( not for vaisyas )
42. Serving the lowly
44.Killing insects, worms, birds
45. Eating whatever has been brought with alcohol
46. Theft of flowers, fruits, firewood47. Cowardice