Daily Interest Calculator
Calculate how daily compounding accelerates your money's growth with our free interest calculator. Daily compounding credits interest to your account every day, allowing each day's earnings to generate additional interest the next day—maximizing the power of compound interest.
Daily vs Other Compounding Frequencies
| Compounding | $10,000 at 5% APR (1 year) | Final Balance | Effective APY |
|---|---|---|---|
| Daily (365x) | Interest added each day | $10,512.67 | 5.127% |
| Monthly (12x) | Interest added monthly | $10,511.62 | 5.116% |
| Quarterly (4x) | Interest added quarterly | $10,509.45 | 5.095% |
| Annually (1x) | Interest added yearly | $10,500.00 | 5.000% |
The Math Behind Daily Compounding
Daily compounding uses this formula: A = P(1 + r/n)^(nt)
Where:
- A = Final amount
- P = Principal (starting amount)
- r = Annual interest rate (as decimal)
- n = 365 (compounding periods per year)
- t = Time in years
Daily Compound Interest Calculator
``javascript
function calculateDailyCompound(principal, annualRate, years) {
const dailyRate = annualRate / 100 / 365;
const days = years * 365;
const dailyCompound = principal * Math.pow(1 + dailyRate, days);
const annualCompound = principal * Math.pow(1 + annualRate / 100, years);
const additionalEarnings = dailyCompound - annualCompound;
const effectiveAPY = (Math.pow(1 + annualRate / 100 / 365, 365) - 1) * 100;
return {
finalBalance: dailyCompound.toFixed(2),
totalInterest: (dailyCompound - principal).toFixed(2),
advantageVsAnnual: additionalEarnings.toFixed(2),
effectiveAPY: effectiveAPY.toFixed(3) + '%'
};
}
`
Where to Find Daily Compounding
Most high-yield savings accounts and money market accounts compound daily, as do many CDs. When comparing accounts, look at the APY (Annual Percentage Yield) rather than APR—APY already factors in compounding frequency, making comparisons apples-to-apples.
The Projection Behind This Page
Starting from $10,000, adding $200 a month at 7%:
| Year | Deposited | Balance | Growth | Growth on deposits |
|---|---|---|---|---|
| 1 | $12,400 | $13,201 | $801 | 6% |
| 5 | $22,000 | $28,495 | $6,495 | 30% |
| 10 | $34,000 | $54,714 | $20,714 | 61% |
| 20 | $58,000 | $144,573 | $86,573 | 149% |
After 20 years, 60% of the balance is growth rather than money you
put in. That crossover — the point where returns exceed contributions — is the whole reason
compounding is worth waiting for, and it arrives later than most people expect.The Formula
`
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) ÷ (r/n)]
└── initial principal ──┘ └────── regular contributions ──────┘
`
The second term usually dominates. On these numbers the $200 monthly contribution
accounts for the larger share of the final balance, which is the practical lesson: how much
you add matters more than the rate, right up until the balance gets large.
How Long Until It Doubles
The Rule of 72 divides 72 by the rate to estimate doubling time. At 7%:
`
72 ÷ 7 = 10.3 years
`
The exact answer is 10.2 years — the rule is accurate to within a few months
for rates between 6% and 10%, and drifts at the extremes. It works because ln(2) ≈ 0.693 and
72 has convenient divisors.
| Rate | Rule of 72 | Exact |
|---|---|---|
| 2% | 36.0 yr | 35.0 yr |
| 5% | 14.4 yr | 14.2 yr |
| 7% | 10.3 yr | 10.2 yr |
| 10% | 7.2 yr | 7.3 yr |
| 15% | 4.8 yr | 5.0 yr |
Compounding Frequency at This Rate
A nominal 7% turns into a different effective yield depending on how often it
compounds — this page uses daily:
| Compounded | Effective annual yield |
|---|---|
| Annually | 7.000% |
| Quarterly | 7.186% |
| Monthly | 7.229% |
| Daily | 7.250% |
| Continuously | 7.251% |
The gap between annual and monthly is worth having. The gap between monthly and daily is
0.021 percentage points — rounding. Compare accounts on
APY, which already folds the frequency in, rather than on the nominal rate.Inflation Is the Number That Matters
A 7% nominal return against 3% inflation is a 4.0% real return.
Real return is what buys anything:
`
real ≈ nominal − inflation
``
Over 10 years, 3% inflation cuts purchasing power by about 26%. A projection quoted in nominal dollars therefore overstates what the money will actually be worth, which is why retirement targets are usually stated in today's dollars.