Future Value (Compound Interest)
The ending balance with compounding is FV = P × (1 + r/n)^(n×t), where P is the principal, r is the annual rate as a decimal, n is the number of compounding periods per year, and t is the time in years.
Finance
About Money Market Calculator
Calculate money market returns with APY, 7-day yield, taxes, target savings, comparisons, and a cash growth chart.
About this calculator
What this does
Calculates the future value of a money market deposit using APY, daily compounding, and 7-day yield. Supports after-tax earnings calculations, target savings mode to find the required principal or rate, and comparison rows for side-by-side scenario analysis with a growth chart.
Who it is for
Savers and investors who want to estimate returns on money market accounts or money market funds. Useful for comparing deposit accounts, planning savings goals, and understanding how compounding frequency affects growth.
How it works
The calculator applies the chosen compounding frequency (daily, monthly, quarterly, annually) to the principal over the selected time period. In target mode it solves for the required principal or rate to reach a goal balance. After-tax results apply the entered tax rate to the gross interest earned to show net earnings.
Limitations
Assumes a constant APY throughout the entire period and does not model rate changes, withdrawal penalties, or tiered interest structures. The 7-day yield is a backward-looking measure and does not guarantee future performance.
Formula
Effective APY from Nominal Rate
APY = (1 + r_nominal/n)^n - 1 converts a nominal rate compounded n times per year into the effective annual percentage yield, reflecting the true return including compounding.
After-Tax Balance
The after-tax balance is afterTax = P + (FV - P) × (1 - taxRate), which reduces only the interest earned by the tax rate while leaving the original principal untouched.
Target Principal
To find the principal needed to reach a savings goal, the calculator solves P = target / (1 + r/n)^(n×t), working backward from the target balance.
How it works
Step 1
Enter the deposit
Add the principal, rate type, rate, and savings period.
Step 2
Adjust taxes or target mode
Optionally add a tax rate or switch on target amount mode for goal planning.
Step 3
Compare the result
Review ending balance, interest, effective APY, after-tax balance, comparison rows, and the chart.
Reference ranges
High-Yield Money Market APY
High-yield money market accounts typically offer APYs in the 3-5% range in normal rate environments. Rates move with the federal funds rate and vary by institution.
Compounding Frequency Impact
Daily compounding earns roughly 0.01-0.05% more effective APY than monthly compounding at typical rates, with the gap widening at higher rates and longer terms.
7-Day Yield Range
Prime money market fund 7-day yields typically range from 2% to 5.5% depending on the fund's expense ratio, portfolio composition, and prevailing short-term interest rates.