Daily Compound Interest Calculator
Daily compounding earns interest on your interest 365 times a year. Over decades, that frequency edge compounds into a real difference. See it for your numbers.
About this tool
A compound interest calculator focused on the often-overlooked variable: compounding frequency. Compare daily compounding against monthly, quarterly, semi-annual, and annual — on the same principal, rate, and horizon. See where the frequency premium is meaningful (long horizons, high rates) and where it is negligible.
How to use it
Quick steps to get the most out of this utility.
- 1
Enter principal
The lump-sum amount you are compounding. Use the same number for all frequency scenarios.
- 2
Set interest rate
The stated annual rate. The calculator handles the frequency conversion automatically.
- 3
Choose horizon
Longer horizons exaggerate the frequency premium. Frequency matters much more over 20 years than over 3.
- 4
Pick frequencies to compare
Daily vs monthly is the most common comparison — typical for savings accounts and short-term investments.
- 5
Read the comparison
See final corpus for each frequency. The "daily premium" is the dollar gap between daily and the next-best option.
What "compounding frequency" actually means
When a bank quotes a 6% annual rate compounded daily, they divide 6% by 365 to get the daily rate (~0.0164%), then apply that 365 times. Each day's interest is calculated on the previous day's balance — including all previously credited interest. Annual compounding only adds interest once a year, so for 364 days each year, the interest sits idle and earns nothing. Daily compounding eliminates that idle period entirely.
The frequency premium, illustrated
- $10,000 at 6% for 10 years — annual compounding: $17,908. Daily: $18,221. Premium: $313 (1.7%).
- $10,000 at 6% for 30 years — annual: $57,435. Daily: $60,496. Premium: $3,061 (5.3%).
- $10,000 at 12% for 30 years — annual: $299,599. Daily: $359,649. Premium: $60,050 (20%).
The honest takeaway
Compounding frequency is a real but second-order effect. The first-order levers are the rate, the time invested, and the amount. If you are choosing between two savings products with identical rates, daily compounding wins. If one product offers a 0.5% higher rate at lower compounding frequency, take the rate. The calculator is here so you do not have to guess which one matters more for your specific situation.
Frequently asked questions
How much extra do I earn with daily vs monthly compounding?+
At 6% over 10 years on $10,000: daily compounding gives roughly $18,221, monthly gives $18,194 — a $27 difference. At higher rates and longer horizons the gap grows. At 12% over 30 years on $100,000: daily = $3,596,485, monthly = $3,494,964 — about $100k extra from daily. The frequency premium scales with both rate and time.
Which products actually compound daily?+
Most US high-yield savings accounts, money market accounts, and many CDs compound daily. Most credit cards charge interest compounded daily on revolving balances (which is why credit card debt is so devastating). Indian savings accounts compute interest daily but credit it quarterly — effectively daily compounding for the saver. Mutual funds and ETFs do not "compound" in the traditional sense — they reinvest continuously, which is mathematically equivalent to continuous compounding (slightly more than daily).
Is "continuous" compounding different from daily?+
Mathematically yes, practically no. Continuous compounding (using e^rt) is the theoretical limit as compounding periods approach infinity. The gap between continuous and daily compounding on a 10-year, 6% investment is roughly $0.50 per $10,000 — meaningless for any practical decision. Daily is essentially continuous for real-world planning.
Does compounding frequency matter for SIPs and recurring deposits?+
Less than for lump-sum investing. With SIPs, the compounding effect on each month's contribution is similar regardless of internal compounding frequency. What matters more is consistency, total contributions, and the average return rate. Frequency optimization is a high-leverage decision for large lump sums (inheritance, bonus, sale proceeds) and a low-leverage one for ongoing SIPs.
Should I switch banks just for daily compounding?+
Almost never. The frequency premium between daily and monthly compounding at typical savings rates is 2–4 basis points — barely worth the switching friction. The much larger lever is the headline rate itself: a 4.5% high-yield savings account at any frequency beats a 0.1% traditional savings account at daily compounding by a 45× margin. Optimize the rate first; the frequency is a footnote.
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