Many astrology classics like Brihat Parashar Hora Shastra have given different Avashthas (States) of planets and their interpretation. The good part it there is no subjectivity or scope for any interpretation. It is plain calculation and simple mathematics. After doing below Maths, one can easily judge the effects or results of the Mahadasha one is undergoing (for the newbies one can download any astrology software feed in basic birth details and check out the Mahadasha they are running). I will explain the computation with the help of an example:

Say for example, native with above birth chart wants to know how his Venus Mahadasha would unfold. We all know total years of Venus Mahadasha is of 20 years. (Mahadasha periods of planets -Sun 6 years, Mars & Ketu -7 years, Moon -10 years, Jupiter -16 years, Mercury -17 years, Rahu -18 years & Saturn -19 years).

The first house is called Lagna. Venus is placed 12^th from Lagna [call this number 12 as A]. Aries is the first Rashi so always count the position of Mahadasha planet from Aries. In this example it is 4 [call this number 4 as B]. Now, add A + B and multiply the answer by 2, answer is (12+4) *2 =32 [call this number 32 as C]

Now multiply C with the respective number of years of the Mahadasha planet, in this case 20 Years of Venus, 32*20 =640 [call this number 640 as D]

Now, Divide D by 27 (as there are total 27 Awasthas or States) and the remainder which you get would be the results you can expect in that planet’s Mahadasha. In this case 640/27 = Remainder is 19. Below is the description of results one can expect from the Mahadasha planet. The serial number being the remainder. Please note the last Serial Number 27 will never come as a remainder as it becomes perfectly divisible by 27, so people getting remainder as zero should refer 27^th point below for expected results. Please do not take literal meaning of the Awasthas, interpret it as per your environment.

1. Snanam (Bathing): Good issues, Conjugal happiness, Respected by Kinsmen, Success in endeavors.
2. Vastra Dharanam (Wearing Clothes): Honored by King and Government, acquisition of money, clothes and precious metals, scents, perfumes and ornaments. Possessing good strength.
3. Vibhuti or Gandha-alankaram (Fame or Scented Decoration): State honours, happiness and mirth, ability in work.
4. Shivalingam or Pooja (Attempt to worship): Money through lands, acquisition of vehicles, happy living, revered by kinsmen.
5. Panchaakshar japam (Chanting of five letters): Acquisition of lands and money; trouble by government; loss of money.
6. Shiva Pooja (Worship of Ishwara): Association even with wicked man, love of people, monetary gains.
7. Upasan or Yagna yathman (Trying to perform sacrifice): Heart disease, educational discourses, professorship, liver complaint.
8. Vishnu Pooja (Worship of Vishnu God): Felicity, monetary gains through relatives and Lands, winning over enemies.
9. Namaskar (Salutation): Pleasing talk, good vehicle, deceitful.
10. Giripradakshinam (Circumambulating the mountain): Diseases of spleen, diarrhoeic fever, trouble from government, worship of Goddess Durga.
11. Rudra Pooja (Worship of Rudra): Head of a village or town or city; prosperity to wife and children; increased financial facility and happiness.
12. Athithi Pooja (Worship of Guests): Showy, Rajo Gunam, acquisition of treasure trove, mantravaadi (one who knows spell or chants).
13. Bhojanam (Meal Time): Bereft of rituals of caste and cosmopolitanism, teasing and hating others, always sickly and unhappy.
14. Udakapadam (Foot of water pot): Eating prohibited food and enmity with relatives and friends.
15. Kopam (Anger): Poverty, one who teases and envys.
16. Thamboolam (Chewing):  Acquisition of clothes, vehicles, money and good conduct, acquainting with Kings and Emperors. Dexterity in speech and efficient management.
17. Aasthana or Devasabha (Assembly of Deities): Good heart, balanced conduct, Indolent (Nidhani), fructification of spells and chants (Mantra Siddhi), helping nature, one of good morals.
18. Kirita Dharanam (Wearing Crown): Army commandant, monetary gains, educated and renowned.
19. Rahasyam (Secretive): Good words, secretive and lazy.
20. Aalasyam (Indisposition): Lazy, dull, an idiot, one who knows Shashtras.
21. Nidra or Seshashayana (Sleepy): Adept in doing other’s work, highly lustrous and irritable, teaser of mother, wife, etc.
22. Jalapana (Drinking water): Enmity with his kinsmen, elders and preceptor, sickly.
23. Amrithapanam (Drinking Nectar): Healthy, happy wife and children, affluent meals, revered by King or Government.
24. Dhan-aarjana (Earning money): Respectable, wealthy, success in undertakings, multiple profiteering.
25. Kirita Visarjana (Removal of Crown): Loss of profession and status, unhappiness, rebuked by people and discarded, respectless.
26. Athi Nidra (Excessive sleep): Tamasic (Madonmatta), crippled by rheumatism and liver diseases, opposed by or opposing Government -Raj Virodhi.
27. Stree Sambhogam (Intercourse with woman): Highly lustrous and irritable, balance others, vexed by sorrow.