What this estimate includes
This calculator is designed for a quick planning comparison, with every important assumption visible. It includes:
- Goal amount and current balance
- A consistent end-of-month contribution
- A constant APY approximated with monthly compounding
How the calculation works
Next balance = current balance + (current balance × APY ÷ 12) + monthly contribution
Results update as you type. Rounding happens for display; calculations use the full values entered. A real statement, pay stub, contract, or account agreement may use different timing and rules.
A worked example
Starting with $2,500 and adding $450 monthly toward $15,000 at a 4% APY reaches the estimate in a little over two years.
Important limitations
This is an educational estimate, not financial, tax, legal, or employment advice. It cannot account for every local rule, fee, benefit, deduction, compounding convention, or personal circumstance. Use it to understand direction and scale, then verify an important decision with the relevant employer, lender, account provider, or qualified professional.
Frequently asked questions
Is APY guaranteed?
Not usually for savings accounts. Rates can change. Certificates may fix a rate but can restrict access or charge early-withdrawal penalties.
What if I contribute on payday?
Earlier deposits can earn slightly more interest. This calculator uses a simple monthly contribution for a practical estimate.
Reviewed August 17, 2026. We review formulas and explanations for clarity. If you spot a problem, please tell us.