Current balance, target, monthly deposit, nominal annual return—estimated months with monthly compounding (simplified).
Each month: balance = balance × (1 + annual%÷100÷12) + monthly deposit, repeated until balance ≥ target − 0.01 or 1200 months elapse (then shows >1200). Requires target > starting balance, positive deposit, non‑negative rate and balance.
This calculator uses plain decimal numbers. If a result looks wrong, check whether you used a comma instead of a dot (or vice versa) where the field expects one.