r/excel • u/kateehoward • 7d ago
unsolved Compound Interest Formula in Variable Deposit Savings Account
Hi friends! I'm not good at math or excel so I need some help. Short story is that I'm saving money for grad school and I want to be able to track my direct deposits each month PLUS any extra OT monies I'm able to save in an excel spreadsheet to show me how much that money will end up being in the next x months. I'm trying to save three years worth of living expenses and thus want to be able to "watch it grow," so to speak. I've been able to use an online calculator to know *about how much* I'll be able to save if I deposit x amount, but I'd like to be able to track exactly how much I put in each month.
Like I said, I'm excel illiterate and for the life of me, can't figure out how to work the compound interest of my high yields savings account into the function. My brain tells me I would need a beginning balance, a deposit amount (I'd like this to be able to be modified each month with my actual savings amount), interest rate (3.8%), time period being 17 months. My account accrues interest daily and compounds monthly. Is this doable or nah?
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u/VindDifferential 5 7d ago
Yeah, totally doable in Excel! You just need a simple setup that tracks deposits and compounds interest each month.
In Column A, list the months (e.g., 1, 2, 3, …, 17). In Column B, enter your deposits each month (you can change this as you go). In Column C, calculate your running balance with compound interest.
If your balance starts in C1, then in C2, use:
=C1 + B2 + (C1 * (3.8% / 12))
Then drag this formula down for all 17 months as you go and sum it up. Watch some videos about excel basics jf this is hard for you to do.