Daily Compound Interest Calculator
Calculate how a lump sum grows with daily compounding interest, plus optional recurring deposits, with a full growth breakdown
Last updated: 2026-08-03
Daily compounding means interest is calculated and added to your balance every single day, rather than monthly, quarterly, or annually -- so each day's interest immediately starts earning interest of its own the very next day. Because the interest is applied more frequently, daily compounding produces a slightly higher return than monthly or annual compounding at the exact same stated annual rate, which is why many high-yield savings accounts, money market accounts, and some credit card balances compound daily. This calculator is fixed to daily compounding on purpose -- it also supports an optional recurring deposit (daily or monthly), so you can model not just a one-time lump sum but an ongoing savings plan, and shows a year-by-year growth chart alongside the headline numbers.
Daily Compound Interest Formula
O(n) in the number of daysA = final amount · P = principal · r = annual interest rate (decimal) · t = years
Example: Invest $10,000 at 5% annual interest, compounded daily for 10 years: A = $10,000 × (1 + 0.05/365)^(365×10) A = $10,000 × (1.000137)^3650 A = $16,486.65
Your interest earned = $16,486.65 - $10,000 = $6,486.65
With recurring deposits: If you add a recurring contribution, this calculator adds it to your balance at the end of each period (each day, or once every 30 days for "monthly") rather than the beginning -- so a deposit doesn't start earning interest until the following period. That matches the convention used by established daily-compound-interest calculators, and treats each "month" as a fixed 30-day block for simplicity, since a day-by-day schedule has no calendar concept of variable month lengths.
Why daily instead of the compounding-frequency dropdown? This site's general Compound Interest Calculator lets you pick annual, monthly, quarterly, or daily compounding. This calculator is a dedicated version fixed to daily compounding -- daily is the single most common schedule for savings and money-market accounts, and always compounding daily lets this tool add a growth chart and recurring-deposit support without a compounding-frequency input getting in the way.
Use Cases
High-Yield Savings and Money Market Accounts
Most online high-yield savings and money market accounts compound daily. See exactly how much a lump-sum deposit grows over months or years at your account's stated rate.
Modeling a Recurring Savings Plan
Add a recurring daily or monthly deposit to see how a savings habit -- not just a single lump sum -- compounds over time.
Comparing Daily vs. Monthly Compounding
Run the same principal, rate, and term through this calculator and the general Compound Interest Calculator (set to monthly) to see exactly how much daily compounding's more frequent interest application is worth in dollars.
Cryptocurrency and DeFi Staking
Many staking and lending platforms advertise daily-compounding rewards. Model expected growth the same way you would for a bank account, keeping in mind that crypto yields are typically far less stable than a bank's advertised rate.
Understanding Daily-Compounding Debt
Credit card balances often accrue interest daily on the average daily balance. This calculator can illustrate how quickly an unpaid balance grows if no payments are made, though real card agreements have additional rules (grace periods, minimum payments) not modeled here.
Frequently Asked Questions
How is this different from the site's general Compound Interest Calculator?
The general Compound Interest Calculator lets you choose any compounding frequency (annual, semi-annual, quarterly, monthly, or daily) via a dropdown. This calculator is a dedicated tool fixed to daily compounding -- the most common real-world schedule for savings and money-market accounts -- and adds a feature the general calculator doesn't: an optional recurring deposit (daily or monthly), so you can model an ongoing savings plan rather than just a single lump sum. If you specifically need to compare compounding frequencies side by side, use the general calculator or the APY Calculator instead.
Why does daily compounding earn more than monthly or annual compounding?
Interest is added to your balance more often, so each day's interest starts earning interest of its own sooner. At the same stated annual rate, daily compounding always produces a result that is equal to or greater than monthly, quarterly, or annual compounding -- though for typical savings rates the difference over a year is usually small (a fraction of a percent), growing larger at higher rates or over longer terms.
Are deposits added before or after interest is calculated each day?
Interest is applied first, then the recurring deposit (if any) is added at the end of that period -- so a new deposit doesn't earn any interest until the following period. This matches the convention used by established daily-compound-interest calculators rather than crediting interest on a same-day deposit.
Why does "monthly" contribution use 30-day months instead of real calendar months?
This calculator runs a day-by-day simulation rather than tracking calendar dates, so "monthly" is approximated as a fixed 30-day interval (12 contributions per 360 days) for simplicity. Over a full year this adds roughly one extra 30-day period compared to 12 real calendar months, a small approximation that established calculators using the same day-based approach also make.
Does this calculator account for taxes or account fees?
No -- it shows the gross growth of your balance at the stated rate. Interest earned in a taxable account is generally taxable income in the year it's earned (consult the IRS or a tax professional for your specific situation), and some accounts charge maintenance or below-minimum-balance fees that would reduce actual growth.
What interest rate should I enter?
Use your account's stated APY or interest rate as disclosed by your bank. If you only have a nominal rate that isn't already daily-compounded, note that banks are required to disclose APY under Truth in Savings (Regulation DD) precisely so depositors don't have to do this conversion themselves -- see our APY Calculator if you need to convert between a nominal rate and APY.