Work through the task
Explore a hypothetical fixed-rate balance with monthly compounding and end-of-month deposits.
- Enter principal, monthly deposit, annual rate and a whole number of months.
- Read the balance, total contributions and calculated growth separately. A fixed assumed rate does not forecast an actual return.
- Review the result before copying or downloading. Editing an input invalidates the previous result; keep an original if the transformation matters.
Example to check
Principal 1,000, deposit 100 per month, rate 0, months 12 → balance 2,200, contributions 2,200, growth 0.
Limits and output behavior
Use finite values within the bounds shown by the controls. This calculator uses floating-point arithmetic and rounded display values; an exported decimal is not a promise of exact accounting precision. The monthly-deposit timing and compounding convention are fixed by this model.
Troubleshooting
Check the principal, end-of-month deposit, annual rate and whole-number month count. Missing values, out-of-range terms or an unrepresentable result are rejected.
Questions
Why is this not a forecast of an investment return?
The model repeats one hypothetical rate and deposit timing. It does not model changing returns, taxes or fees, and does not choose assumptions for you.
Input and privacy
Processing runs in this browser. Inputs are not saved automatically. An explicitly chosen local draft, where offered, is plaintext storage on this device. Downloaded files, clipboard contents and browser extensions have separate retention behavior.