Compound Interest Calculator
See how an initial balance, regular contributions, withdrawals, and compounding can change your savings over time.
- Future balance and interest earned
- Monthly and yearly breakdowns
- Nominal rate or APY
Free · private · no signup
Personal finance calculators
Get a clear answer to a money question without creating an account. Koody's free calculators show the assumptions, explain the math, and run entirely in your browser.
Retirement Calculator
Compare projected savings with an editable retirement-income goal, then estimate how much more you may need to save each month.
- Future and today's-dollar results
- Optional estimate for other retirement income
- Additional monthly saving estimate
Tip Calculator
Calculate gratuity before or after tax, account for an existing service charge, and split the final bill.
- Common and custom percentages
- Per-person bill, tip, and total
- Optional dollar rounding
Start with the question
What can these tools help answer?
How much could my savings grow?
Use the compound interest calculator to separate what you deposit from estimated investment growth.
Am I on track for retirement?
Test a retirement age, spending goal, other income, and return assumptions in one consistent projection.
What should each person pay?
Use the tip calculator to make the tax basis, service charge, gratuity, and split visible.
Built for clarity
How Koody calculators work
These are educational tools for exploring scenarios, not forecasts, guarantees, or personal financial advice.
Transparent math
Each calculator explains its formula, timing rules, and worked example.
Editable assumptions
Defaults are starting points. Rates, timing, inflation, and other assumptions stay visible and editable.
Private by design
Raw calculator inputs stay in this browser. They are not saved or sent to Koody.
Open access
No account, bank connection, cookie, geolocation, or third-party calculator is required.