A Math Student's Very Overthought Approach to Saving Money in College

I want to be transparent that this post contains spreadsheets, that the spreadsheets were unnecessary, and that I built them anyway because I am a Mathematics student at IIT Kanpur and applying quantitative frameworks to my life is my coping mechanism for the parts of life that are not fundamentally quantitative. Finance in college is technically quantitative but the important parts are not, and it took me two years to understand the difference.

The Spreadsheet Phase

At the start of my second year I built a Google Sheet that tracked every rupee I spent, categorised into 22 categories, with month-over-month trend lines and conditional formatting that turned red when any category exceeded its budget. This was a functional and somewhat excessive response to the observation that I was spending more than I intended and not knowing where it went.

The spreadsheet worked at identifying where money went. I discovered I was spending ₹800 a month on impulse food orders at midnight, which I had classified under 'stress management' in my mental budget and which the spreadsheet unkindly placed under 'eating out.' I cut this by about 60% by the simple intervention of not having the Swiggy app on my home screen, which removed the friction-free impulse pathway.

What the Spreadsheet Could Not Do

It could not tell me whether spending ₹300 on a book I wanted was worth it. It could not tell me whether the extra ₹500 for the nicer room on the exchange program was a good use of money. It categorised these correctly but it had no framework for evaluating spending that was not obviously waste.

The framework I eventually found useful was one I arrived at by reading, not by math: separate spending into things that improve your situation for one day and things that improve it for longer. An expensive dinner with good people might be both, depending on the dinner. The ₹800 in midnight orders was reliably just the former.

The Actual Useful Habits

Three habits that I have maintained and that have a positive compound effect: setting aside 10% of any income the day it arrives before spending any of it, keeping a rough monthly awareness of total spend without necessarily tracking every line, and having one specific thing I was saving toward at any given time — a trip, a course, a piece of equipment — which made the savings feel concrete rather than abstract.

The spreadsheet still exists. I open it about once a quarter now, which is probably the right frequency. The 22 categories have been consolidated to six. The conditional formatting is still red when things go over. It is still somewhat excessive. I have made peace with this.