How much it cost for four years

Hii
You have not mentioned the course for which you wish to know the fees. But as you mentioned that you need the cost for 4 years, so i suppose you want the details for BTech course. The fees structure for BTech course in IIT Madras is as follows:
Academic Fees :
Caution Money ( One Time, Refundable ) - Rs . 2000
One Time Fees- Rs . 3050
Tuition Fee ( per Semester )  Rs . 100000
Other fees ( per Semester )- Rs . 2600
Annual Fees- Rs . 1297
Total- Rs. 108947( to be paid at the time of admission )
Hostel Fees:
Hostel Caution Money ( One Time, Refundable )- Rs . 3000
Hostel Admission Fee ( One Time )- Rs . 250
Hostel Seat Rent ( per semester )- Rs . 5000
Electricity and water charges ( per semester )- Rs . 750
Other Charges ( per semester )  Rs . 7500
Advance Dining Charges ( six monthly )  Rs . 18180
Total- Rs. 34680 ( to be paid at the time of admission )
The above mentioned details are for the fees that is to be paid at the time of admission. The total cost for 4 years would be as follows.
Total Academic fees except for one time payments-

• Tuition Fee ( per Semester )  100000 * 8 = Rs . 800000
• Other fees ( per Semester ) - 2600 * 8 = Rs . 20800
• Annual Fees - 1297 * 4 = Rs . 5188

TOTAL=Rs . 825988

Total Hostel fees except for one time payments -

• Hostel Seat Rent ( per semester )- 5000 * 8 = 40000
• Electricity and water charges ( per semester )- 750 * 8 = 6000
• Other Charges ( per semester )  7500 * 8 = 60000
• Advance Dining Charges ( six monthly )  18180 * 8 = 145400

TOTAL-Rs . 251400

One time payments-
Caution Money - Rs . 2000
One Time Fees ( college )- Rs . 3050
Hostel Caution Money - Rs . 3000
Hostel Admission Fee - Rs . 250
Total- Rs . 8300
So one you wishes to avail hostel facility also will have to spend a total of Rs . 1085688 for 4 years and those you do not stay in the college hostel will have to spend a total of Rs . 831038 for 4 years.
College provides some fee waiver as follows:

• 100% Tuition Fee waiver for SC/ST/PH students.
• Full remission of the Tuition Fee for General and OBC students whose family income is less than Rs.1 lakh per annum.
• Remission of 2/3rd of the Tuition Fee for General and OBC students whose family income is between Rs .1 lakh to Rs . 5 lakh per annum.

I hope this answer helps you clear your doubt
Thanks!!