Compound Savings Calculator
The Compound Savings Calculator projects how a starting balance plus fixed monthly deposits grow over time with compound interest, showing contributions vs interest earned.
What this means
Two forces grow your savings: what you add each month and the interest that compounds on the growing balance. Over years, the interest can exceed everything you deposited.
How we calculate it
Formula
FV = P(1+r)^n + C × ((1+r)^n − 1)/r — with P start, C monthly deposit, r monthly rate, n months.Worked example
$5,000 starting, $200/mo for 10 years at 5%:
- 1FV = 5,000 × (1.004167)^120 + 200 × ((1.004167)^120 − 1)/0.004167
- 2Future value ≈ $39,286
- 3Contributions = $29,000, interest ≈ $10,286
Important assumptions
- Deposits are made monthly at the start of each month.
- The annual rate stays constant.
Frequently asked questions
When should I start saving?
The earlier the better — compounding rewards time more than any other factor. Even small early deposits beat large late ones.
How does compounding frequency matter?
More frequent compounding credits interest to your balance sooner, producing slightly higher growth at the same nominal rate.