Money Market Account Calculator

Project a money market account from opening deposit, APY, monthly contributions, target reserve, and term, then compare goal timing, deposit-only growth.

Last updated 30 March 2026

Example plans

Opening deposit ($) Monthly contribution ($) Reserve target (optional) Stated APY (%)

Projection length (years) Crediting frequency

Display currency

Switch the displayed currency for balances and contributions without changing the projection maths.

Currency

Assumptions

This planner treats the entered APY as the bank’s effective annual yield, converts it into an equivalent rate path for the selected crediting frequency, and assumes month-end contributions. It does not include taxes, tiered rates, fees, minimum-balance rules, or future APY changes.

Money market plan

$29,209.76

Estimated balance after 5 years at 4.5% APY with $250.00 monthly contributions.

Total contributions: $25,000.00
Total interest: $4,209.76
Interest share: 14.41%
Monthly-equivalent growth: 0.37%

Deposit-only baseline

$12,461.82

What the opening deposit alone would become if you made no extra monthly deposits.

Contribution lift

$16,747.94

Extra projected balance created by the monthly deposits beyond the opening balance path.

Reserve target

$30,000.00

Progress at the selected horizon: 97.37%.

Estimated time to target

5 years 3 months

Gap at 5 years: $790.24.

APY comparison

Scenario	APY	Ending balance	Interest
Lower APY	3.5%	$28,220.73	$3,220.73
Base APY	4.5%	$29,209.76	$4,209.76
Higher APY	5.5%	$30,230.86	$5,230.86

Year-by-year plan

Year	Balance	Contributions	Interest
1	$13,511.38	$13,000.00	$511.38
2	$17,180.78	$16,000.00	$1,180.78
3	$21,015.30	$19,000.00	$2,015.30
4	$25,022.37	$22,000.00	$3,022.37
5	$29,209.76	$25,000.00	$4,209.76

Planning insight

At the current settings, monthly deposits contribute $15,000.00 over the term while interest contributes $4,209.76. That makes it easier to judge whether the balance is being driven mostly by cash added, by yield, or by both.

The entered APY is already an annualized deposit yield, so changing the crediting frequency mainly changes the equivalent nominal rate path used behind the scenes rather than transforming the economics the way a loan APR would. The bigger real-world variable is usually whether the bank changes its APY later.

Use this projection for liquid cash planning and compare it with a CD or savings account only after checking access limits, minimum balances, fees, and whether the quoted APY is variable.

About this calculator

General-reference calculator Reviewed 30 March 2026 Updated 30 March 2026

Editorial responsibility

Calcipedia editorial team

This page is maintained against the site trust model for its topic and updated when formulas, sources, or guidance materially change.

Formula provenance

Formula notes are kept in the page explanation when a named standard or reference materially affects the result.

Methodology

Uses the entered APY to derive an equivalent nominal rate path for the selected crediting schedule, projects growth on the opening deposit and month-end contributions across the chosen term, estimates reserve-goal timing when a target is entered, and reports ending balance, contributions, interest, baseline growth, and APY scenario comparisons.

Limitations

Assumes one constant APY, one constant compounding basis, and end-of-month contributions.
Does not model taxes, fees, minimum-balance rules, rate changes, withdrawal limits, balance tiers, or promotional terms.
The projection is only as accurate as the user's deposit, contribution, and term assumptions.
This is a deposit-planning estimate, not a bank quote, guarantee, forecast, or personalized financial recommendation.

Disclaimer

Use the output as a planning estimate only. Before opening, funding, or switching an account, compare the result with the institution's current disclosure, fee schedule, balance-tier rules, access limits, and any rate conditions that can change the realized return.

Formula notes

Consumer Financial Protection Bureau — 12 CFR 1030.2 — Official Truth in Savings definitions for APY and related deposit-account disclosure terms.
Consumer Financial Protection Bureau — Appendix A to Part 1030 — Official APY computation appendix supporting the deposit-yield framework used here.
FDIC — Deposit Accounts — Official FDIC consumer page confirming money market accounts as deposit products and outlining common account features.
FDIC — National Rates and Rate Caps — Official FDIC rate reference reinforcing that quoted deposit yields vary across institutions and time.

Change notes

Change note: this page's updated date changes only when the formula, labels, examples, or user guidance materially changes. Cosmetic or deploy-only edits do not refresh the date.

See our calculation methodology and editorial standards, plus the editorial contact route, for how this estimate is produced and corrected.

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Deposit Account Planning

Money market account calculator guide: project APY growth, reserve targets

A money market account calculator estimates how an opening deposit and ongoing monthly contributions may grow at a stated annual percentage yield, then compares the result with a reserve target and alternate APY scenarios. It is useful when you want a liquid cash projection that sits between a basic savings account and a more restrictive product such as a CD.

What a money market account calculator is really planning

A money market account is a bank deposit account, not a money market mutual fund. This calculator is modelling deposit-account maths only: an opening balance, a stated APY, optional month-end contributions, and the time horizon over which those cash balances remain on deposit.

That makes it most useful for emergency funds, home buffers, tax reserves, or other short- to medium-term cash goals where liquidity still matters. It is not trying to estimate stock-market returns or risk-adjusted portfolio growth.

How APY, compounding, and monthly deposits affect the projection

APY already reflects one year of compounding. The calculator uses that APY to derive the equivalent growth path for the selected crediting basis, then projects both the opening deposit and any monthly contributions across the chosen term.

Monthly contributions are treated as end-of-month deposits. Earlier deposits therefore have more time to earn than later ones, which is why the year-by-year schedule and lower/base/higher APY comparison rows are helpful when planning a real reserve goal.

APY = (1 + periodic rate)^periods per year - 1

The APY relationship used to translate the stated deposit yield into a compounding basis for the projection.

Ending balance = Growth on opening deposit + Growth on monthly contributions

Shows how the projected balance is split between the opening deposit path and the month-end contribution path.

Goal timing matters as much as the ending balance

For money market accounts, the question is often not just “what balance do I end with?” but also “when do I reach the reserve I want?” That is why this planner supports an optional target balance and estimates how long the current deposit pace may take to reach it.

This is especially useful for emergency-fund planning, because the same ending balance can feel very different depending on whether the target is reached in 18 months, 3 years, or not within the selected horizon at all.

Worked example: 10,000 opening deposit, 250 per month, 4.50% APY, 5 years

Suppose you start with 10,000, add 250 each month, and earn 4.50% APY for five years. The calculator shows the projected ending balance, the total contributions, total interest, and what the opening deposit alone would have become without the monthly additions.

That baseline comparison separates savings behaviour from yield. If most of the ending balance still comes from your own deposits, the practical lever is contribution pace. If interest becomes a larger share later in the timeline, you can see how the reserve begins to carry more of its own growth.

What this estimate does and does not cover

This calculator assumes one constant APY, one constant crediting basis, and month-end contributions. It does not model taxes, account fees, balance tiers, minimum-balance rules, teaser rates, transfer limits, or the possibility that the APY changes later.

Use it as a deposit-planning estimate, then compare the result with the specific bank's disclosures and account terms before relying on it for a real savings decision. A money market account can be a useful liquid-cash tool, but the practical result depends heavily on access rules and future yield changes.

Further reading

Consumer Financial Protection Bureau — 12 CFR 1030.2 — Official Truth in Savings definitions for annual percentage yield and deposit-account disclosure terminology.
Consumer Financial Protection Bureau — Appendix A to Part 1030 — Official APY computation appendix supporting the deposit-yield framework used in this calculator.
FDIC — Deposit Accounts — Official FDIC consumer page confirming that money market accounts are deposit products and outlining common deposit-account features.
FDIC — National Rates and Rate Caps — Official FDIC rate reference showing that quoted deposit yields can change over time and differ across institutions.

Frequently asked questions

Is a money market account the same as a money market mutual fund?

No. A money market account is a bank deposit account. A money market mutual fund is an investment product and does not work under the same deposit-account rules or protections.

Why does the calculator ask for APY instead of APR?

Because deposit accounts are commonly quoted using APY, which already reflects the effect of compounding across one year. That makes it a more natural starting point for a savings projection.

How is this different from a normal savings calculator?

The maths is similar, but the planning context is different. Money market accounts are typically used for liquid cash reserves, so this page focuses on reserve targets, deposit-account APY, and comparison with other deposit products rather than long-term investing assumptions.

Can I use this to estimate how long it will take to build an emergency fund?

Yes, as a planning estimate. Enter the reserve target you want and the calculator can estimate whether the current deposit pace reaches it within the selected horizon or roughly how long it may take if the APY stays constant.

Does changing the display currency change the math?

No. The currency selector changes how values are shown. The projection uses the same numeric deposit, contribution, and APY assumptions either way.

Should I use this to compare a money market account with a CD?

It can help with a first-pass rate comparison, but it does not account for CD early-withdrawal penalties, access constraints, or rate-lock features. Those still need separate review before choosing between products.

Does the calculator assume the APY stays fixed the whole time?

Yes. The projection assumes one constant APY. Real money market account rates can move up or down, which is why the lower/base/higher APY comparison is only a scenario guide rather than a forecast.

Why is the final balance still driven mostly by contributions?

For shorter horizons and liquid deposit accounts, your own deposits usually matter more than yield. Interest becomes a larger share later, but money market accounts generally work best as cash-reserve tools rather than high-growth vehicles.

Does this calculator include taxes, fees, or balance tiers?

No. It excludes taxes, account fees, minimum-balance rules, tiered APYs, and other bank-specific conditions. Those can materially change the realized return.

What if I already have enough saved for the reserve target?

The goal-timing section will show the target as already funded. That can be useful if you want to treat the account as a maintenance reserve instead of a buildup goal.

Can I use this to choose the best bank account?

Only as a first-pass planning tool. You still need to compare the institution's current APY, balance tiers, access rules, transfer limits, and any fees or conditions that may make the headline rate less attractive in practice.

Is this calculator only for U.S. deposit accounts?

The core compounding maths is general, but the trust references and disclosure framing are built around U.S. deposit-account terminology such as APY and Truth in Savings rules.

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