Annuity Calculator
Modify the values and click calculate
Contribution Details
Projected Future Value
Enter your contribution details to project your annuity's growth.
This calculator models the accumulation phase only. Once you're ready to start withdrawals, see our Annuity Payout Calculator. This is an educational estimate only and is not financial advice.
Understanding Annuity Accumulation
An annuity is a contract, typically sold by an insurance company, that lets you build savings over time (the accumulation phase) and later convert that balance into a stream of income (the payout phase). This calculator covers the accumulation phase -- growing an optional lump sum plus regular contributions at a fixed rate. Once you're ready to convert a balance into payments, see the related Annuity Payout Calculator.
Ordinary Annuity vs. Annuity Due
An "ordinary" annuity assumes each contribution lands at the end of the period; an "annuity due" assumes it lands at the beginning, giving that contribution one extra period to grow. The due version always produces a slightly higher future value, all else equal.
Compounding Over Time
Both a starting lump sum and every ongoing contribution compound at your assumed rate for however many periods remain -- earlier contributions have more time to grow, which is why total growth often exceeds total contributions over a long enough horizon.
Consistency Beats Timing
Because monthly contributions compound alongside any lump sum, consistent ongoing contributions -- even modest ones -- often matter more to the final balance than trying to time a single large deposit perfectly.
Accumulation vs. Payout
This calculator answers "how big will my balance grow?" A separate question -- "how much can I withdraw from that balance?" -- is answered by the Annuity Payout Calculator, since the two phases use different math.
Worked Example
Suppose you start with a $5,000 lump sum, contribute $300/month at the end of each period, earning a 6% annual rate over 20 years:
- Total contributions: $5,000 + ($300 × 240 months) = $77,000.
- Projected future value: approximately $155,163.29.
- Total growth: approximately $78,163.29 -- more than the contributions themselves.
Where the Balance Comes From
- Contributions: $77,000.00
- Growth: $78,163.29
Key Takeaways
- This Is the Growth Phase: Use this calculator to project a balance -- use the Annuity Payout Calculator when you're ready to draw that balance down.
- Timing Matters at the Margins: Annuity due (beginning-of-period contributions) always edges out ordinary annuity, given the same inputs.
- Consistency Compounds: Regular monthly contributions, sustained over a long horizon, are often the biggest driver of the final balance.
- This Is an Estimate: Real annuity contracts include fees, surrender charges, and guaranteed minimum rates not modeled here -- review your actual contract terms.