01
Enter your savings
Your starting balance, the annual rate, how long you'll save, and how often interest compounds.
Compound Interest Calculator
Compound interest on a balance and deposits — final balance, APY and real worth.
Updated Reviewed by Sajid Hussain· Editor
How money grows on its own
Compound interest on a balance and your deposits — after frequency and after inflation
A compound interest calculator shows how money grows when interest earns interest — each period's interest is added to your balance, so the next period earns on a bigger base. This one handles the full picture — a starting balance, regular contributions, and a compounding frequency you choose — then shows your final balance, how much is pure interest, the effective yield, and the part most tools skip: what it's really worth in today's money.
The headline is your final balance: your starting principal grown by A = P(1 + r/n)^(n·t), plus the future value of every contribution you add along the way. A 5,000 balance with 100 added monthly at 3% (compounded monthly) becomes 20,720.91 in 10 years — 17,000 of it your own money and 3,720.91 pure interest. We show that three-way split clearly so you always know how much of the result is yours versus compounding.
Most calculators bury the compounding frequency in the formula. We expose it — yearly, half-yearly, quarterly, monthly or daily — and show the effective annual yield (APY) it produces. A 6% rate compounded daily really earns about 6.18% a year, and we show the exact extra balance the frequency adds. You can also set the contribution frequency independently of compounding: deposit monthly into a daily-compounding account, and a deposit earns interest from the next compounding date.
Then inflation. A balance that looks large in 15–20 years buys far less by then. We deflate your final balance to today's purchasing power, and flag the dangerous case where inflation is at or above your rate — when your money is quietly losing value every year despite a rising number.
Compounding milestones and caveats. We surface the exact time for your money to double (the precise version of the Rule of 72), the year your interest overtakes everything you've contributed, your wealth multiple, and the cost of waiting a year. Use it for a savings account, a fixed deposit or CD, a recurring deposit, a bond, or any investment. For a recurring mutual-fund plan use the SIP Calculator; for a one-time investment, the Lumpsum Calculator — this is the general-purpose engine for everything in between. Works in any currency, no rates, no conversion.
Quick facts
- Computes
- Final balance · interest · contributions · real value
- Principal + deposits
- Both in one engine — savings, FD, RD, bonds
- Frequency-aware
- Yearly→daily + the APY it produces
- Inflation-aware
- Value in today's purchasing power
- Doubling time
- Exact, not just the Rule of 72
- Any currency
- Universal math — no rates, no FX
How it works
From a balance and a deposit to a real-money result
A few inputs for the basics, two optional for the depth — under a minute.
02
Add contributions
Set a regular deposit and how often you add it. Leave it at 0 to grow a balance only.
03
Fine-tune (optional)
Add a yearly increase to your deposits and an expected inflation rate.
04
Read the result
Final balance, interest earned, the inflation-adjusted value, your effective yield, and when your money doubles.
Steps to use the Compound Interest Calculator: Enter your savings, Add contributions, Fine-tune (optional), Read the result.
Compound interest formula
The compound interest formula, worked with your numbers
Standard compound-interest math, in plain algebra — the same formulas every authority (the SEC, banks) uses.
01
Future value of the principal
A = P × (1 + r/n)^(n × t)
P = starting balance, r = annual rate (decimal), n = compounding periods per year, t = years. With yearly compounding (n = 1) this is just P × (1 + r)^t.
Example: 5,000 (starting balance) × (1 + 0.03/12)^(12 × 10) = 6,746.77 over 10 years at 3%, compounded monthly.
02
Future value of regular contributions (end of period)
FV = PMT × [ ((1 + i)^N − 1) ÷ i ]
PMT = deposit per period, i = rate per period (r/n), N = number of periods (n × t). Deposits at the start of each period (annuity-due) earn one extra period: multiply by (1 + i).
Example: 100 per month for 120 months at i = 0.0025 adds 13,974.14 — so the total is 20,720.91.
03
Effective annual yield (APY)
APY = (1 + r/n)^n − 1
The true yearly return after compounding. At yearly compounding it equals your nominal rate; compounding more often makes it higher — e.g. 6% compounded daily ≈ 6.18%.
Example: (1 + 0.06/365)^365 − 1 = 6.18% effective, vs the 6% you entered.
04
Inflation-adjusted (real) value
Real Value = Final Balance ÷ (1 + inflation)^years
Deflates the future balance to today's purchasing power, so you know what it can actually buy rather than just its nominal size.
05
Time to double
t = ln(2) ÷ (n × ln(1 + r/n))
The exact time for the balance to double at this rate — the precise version of the Rule of 72 (≈ 72 ÷ rate). At 6% it's about 11.6 years.
Worked example
5,000 to start, 100 a month, for 10 years
Watch the balance build — and then what it's really worth.
Scenario
You start with $5,000.00 and add $100.00 every month for 10 years at a 3% rate, compounded monthly, with 3% inflation. Where do you end up?
1
Step 1 · What you put in
$5,000.00 to start plus $100.00 × 120 months = $12,000.00 in deposits — $5,000.00 + $12,000.00 = $17,000.00 of your own money.
You contribute: $17,000.00
2
Step 2 · Final balance
Compounded monthly at 3%, it grows to $20,720.91 — that's $3,720.91 of pure compound interest on top of what you put in.
Balance: $20,720.91 ($3,720.91 interest)
3
Step 3 · Wealth multiple
$20,720.91 ÷ $17,000.00 = 1.22×. The interest is modest here because 3% is a savings rate over a fairly short term — a higher rate or longer horizon compounds far harder.
Grew 1.22×
4
Step 4 · What it's really worth
Deflated at 3% inflation over 10 years, the $20,720.91 balance is worth about $15,418.00 in today's money. When the rate and inflation are similar, real growth is small — plan around this number.
In today's money: $15,418.00
The takeaway
When rate and inflation are similar, nearly all of $20,720.91 is your own money — compound interest rewards rate and time far more than a short, low-rate plan, so pushing the rate up or extending the horizon turns the $3,720.91 interest slice into the dominant half of the balance.
Rate benchmarks
What interest rate is realistic?
Long-run nominal rates by vehicle, so your rate input is grounded. Equity returns are volatile year to year — these are multi-decade averages.
| Metric | Poor | Average | Good | Excellent |
|---|---|---|---|---|
Savings account Reserve Bank of India Monetary Policy Report | < 1% | 2–4% | 4–5% | 5%+ (high-yield) |
Fixed deposit / CD Reserve Bank of India Monetary Policy Report | — | 5–7% | 7% | 7–8% |
Bonds / debt funds AMFI India — Mutual Fund Industry Data | — | 6–7% | 7–8% | 8%+ |
Hybrid / balanced funds AMFI India — Mutual Fund Industry Data | — | 8–10% | 10–11% | 11–12% |
Large-cap equity / index NSE India — Historical Returns Data | — | 10–12% | 12% | 12–14% |
Realistic planning rate SEBI Investor Education — MF Returns | > 18% (don't) | Match the vehicle | — | Treat extra as upside |
Which calculator
Compound Interest vs SIP vs Lumpsum
All three use the same compounding core; pick the one that matches how your money goes in. This tool is the general-purpose engine for a balance plus deposits.
| Feature | Compound Interest | SIP Calculator | Lumpsum Calculator |
|---|---|---|---|
| Starting balance (principal) | |||
| Regular contributions | |||
| Choose compounding frequency | |||
| Contribution frequency | Monthly to yearly | Monthly only | None |
| Contribution timing | Start or end | Start | None |
| Effective annual yield (APY) | |||
| Inflation-adjusted value | |||
| Best for | Savings / FD / balance + deposits | Monthly mutual-fund plan | One-time investment |
Common mistakes
How compound-interest projections fool people
Comparing products on the nominal rate, not the APY
Why it matters
A 6% rate compounded daily is not the same as 6% compounded yearly — the daily one really earns ~6.18%. Comparing on the headline rate alone makes you pick the wrong account.
Fix
Compare on the effective annual yield (APY), which this calculator shows for whatever compounding frequency you choose.
Ignoring inflation on a savings balance
Why it matters
If your savings rate is 3% and inflation is 3%, your money is standing still in real terms even though the balance keeps rising — the most common illusion in a compound calculator.
Fix
Use the inflation-adjusted value. We warn you outright when inflation is at or above your rate.
Assuming an unrealistic rate
Why it matters
Punching in 15–20% for a "savings" plan makes the balance look incredible, so you save too little. No deposit account sustains that.
Fix
Match the rate to the vehicle: 4–8% for savings/FDs, ~12% for long-run equity. We flag anything optimistic.
Forgetting the compounding frequency entirely
Why it matters
Two accounts with the same rate but different compounding frequencies grow to different amounts — and most tools silently pick one for you.
Fix
Set the frequency to match your product (daily/monthly savings, quarterly FDs) and see the exact bonus it adds.
Waiting to start
Why it matters
The earliest contributions compound the longest, so a one-year delay forfeits an outsized slice of the final balance.
Fix
Start now — the calculator quantifies what waiting a year costs you.
Treating the result as after-tax
Why it matters
Interest is often taxed (e.g. TDS on FD interest, tax on savings interest), and the gross figure overstates what you keep.
Fix
Treat the balance as a pre-tax projection and apply your local tax rules to the interest for a net figure.
Tips
Get more from compound interest
Compare on APY
Judge savings accounts and FDs by their effective annual yield, not the headline rate, since compounding frequency differs.
Start early
Time matters more than amount — the first contributions compound the longest. Starting sooner usually beats saving more later.
Automate contributions
A steady deposit every period is what turns a modest rate into a large balance over time.
Step up your deposits
Raising contributions a few percent a year as income grows compounds into a much bigger result.
Plan in real terms
Target the inflation-adjusted value, especially for long horizons where inflation quietly erodes the headline.
Mind the rate vs inflation gap
If your rate barely beats inflation, your real growth is small — consider a higher-yielding vehicle for long-term money.
Use cases
When this calculator helps
The Compound Interest Calculator works across every stage of the workflow.
Growing a savings account
See what a balance plus monthly deposits becomes at your bank's rate and compounding, in today's money.
Comparing FDs / CDs
Use the compounding frequency and APY to compare fixed deposits fairly, even when their rates and compounding differ.
Planning a recurring deposit
Model a regular deposit (with no opening lump) and watch interest overtake your contributions over time.
Projecting any investment
Combine a starting balance with ongoing contributions at an expected return to see the long-run compounded value.
Understanding the formula
See A = P(1 + r/n)^nt worked through with your own numbers, including the contribution and APY math.
Reverse-checking a goal
Adjust the balance, deposit and horizon until the inflation-adjusted result matches your real target.
Glossary
Compound interest vocabulary
Every important term you'll encounter in this calculator and the broader topic.
- Compound interest
- Interest earned on both your original balance and the interest already added — interest earning interest.
- Principal
- The starting balance you begin with, before any contributions or interest.
- Compounding frequency
- How often interest is added to the balance — yearly, half-yearly, quarterly, monthly or daily. More frequent compounding raises the effective yield.
- Effective annual yield (APY)
- The true yearly return after compounding: (1 + r/n)^n − 1. The fair number to compare savings products with different compounding.
- Contribution
- A regular amount you add to the balance each period (a deposit). Can be on a different schedule than the compounding.
- Annuity-due vs ordinary annuity
- Contributions at the start of a period (annuity-due) earn one extra period of interest versus contributions at the end (ordinary annuity).
- Nominal rate
- The stated annual rate before compounding is applied — lower than the APY when interest compounds more than once a year.
- Rule of 72
- A shortcut for doubling time: about 72 ÷ rate years. This tool shows the exact doubling time from the real compounding.
- Inflation-adjusted (real) value
- A future balance expressed in today's purchasing power, so you know what it can actually buy.
- Wealth multiple
- Final balance ÷ everything you put in — how many times your money grew.
Help & answers
Frequently asked questions
Everything you need to know about how the Compound Interest Calculator works.
01What is a compound interest calculator and how does it work?
Shows how money grows when interest earns interest. Enter balance, rate, term, compounding frequency, and contributions; it applies A = P(1+r/n)^(n·t) plus deposits' future value to return final balance, interest, APY, doubling time, and inflation-adjusted worth.
02What is the compound interest formula?
The formula is A = P(1+r/n)^(n·t), where P is principal, r is the annual rate (decimal), n is compounding periods per year, t is years. A 10,000 balance at 5% monthly for 10 years gives ≈ 16,470. With contributions, it adds PMT × [((1+i)^N−1)÷i], where i=r/n and N=n·t.
03How does daily compound interest differ from monthly or yearly?
More frequent compounding earns slightly more. The difference is the APY: 6% compounded yearly stays 6%, compounded daily it's ~6.18%. Pick yearly, half-yearly, quarterly, monthly or daily in this calculator and see the exact extra balance each frequency adds.
04Can I add regular monthly contributions?
Yes. Enter a contribution and choose its frequency — monthly, quarterly, or yearly — independently of compounding. The calculator shows the three-way split: starting principal, contributions, and interest. Deposits can grow yearly and be set to start-of-period or end-of-period timing.
05What is the difference between the nominal rate and APY?
The nominal rate is what you enter (say 6%). APY = (1+r/n)^n−1 is what it becomes once compounding is applied. At yearly compounding both are equal; compounding more often raises APY — 6% compounded daily is about 6.18%. Compare savings accounts and FDs on APY, not nominal rate.
06Why does this calculator show an inflation-adjusted value?
Your final balance deflated by inflation shows what it can actually buy in today's terms — not just its nominal size. We compute Real Value = Final Balance ÷ (1+inflation)^years. When your rate roughly equals inflation, real growth is near zero even as the number climbs — we warn you outright when inflation is at or above your rate.
07Does the contribution frequency have to match the compounding frequency?
No — set them independently. For example, deposit monthly into an account that compounds daily. The calculator spreads deposits evenly across compounding periods. When both frequencies match (e.g. monthly deposits + monthly compounding), results equal the standard annuity formula exactly.
08How long will it take my money to double?
At 6% your money doubles in about 11.6 years — t = ln(2) ÷ (n × ln(1+r/n)) is the exact formula (compounded monthly). The Rule of 72 quick estimate is 72 ÷ rate years, so 6% gives ~12 years. This calculator shows the exact time for whatever rate and frequency you set.
09Is this a savings calculator, an FD calculator, or an investment calculator?
It is the general-purpose compound-interest engine. Use it for savings accounts, FDs / CDs, recurring deposits, bonds, or any investment where you know the rate and compounding. For a recurring mutual-fund plan use our SIP Calculator; for a one-time investment, use Lumpsum Calculator.
10Does it account for taxes and fees?
No — it projects pre-tax, pre-fee balance (the standard approach). Real returns are reduced by tax on interest (e.g. TDS on FD interest), account fees, and expense ratios for funds. Apply your local tax rules to interest earned for a net figure.
11Does this compound interest calculator work for any currency or country?
Yes — fully global. Enter amounts in any currency and results come back in it. The compounding math is universal; just set the rate, frequency and contributions to match your account.
12Are the results guaranteed?
For fixed-rate products (FDs, bonds) held to maturity the projection is reliable since the rate is fixed. For savings accounts the rate can change, and for market investments it's variable. Treat any variable-return projection as a planning estimate, not a promise.
Keep exploring
Related tools
SIP Calculator
Project your SIP maturity, total returns, and real worth after inflation — free.
Open tool
Lumpsum Calculator
What a lumpsum investment grows into — total value, real worth, year by year.
Open tool
SIP vs Lumpsum Calculator
Compare SIP vs lumpsum on the same sum — verdict, gap, and when each wins.
Open tool
In-Hand Salary Calculator
Convert CTC to monthly take-home with full tax and deduction breakdown.
Open tool
Category
Operational Financial Planning
Subcategory
personal finance
Availability
Global · 9 markets
Price
Free forever
Topics
compound interest calculatordaily compound interest calculatorcompound interest calculator with monthly contributionsmonthly compound interest calculatorcompound interest formulasavings calculatorinterest calculatorcompound interest calculator with regular contributionsfd calculatorinvestment growth calculatorhow to calculate compound interestannual percentage yield calculator
Explore 500+ more tools
Calculators, simulators, and decision tools for every stage of business operations.