How this calculator works
Each period your balance grows by the assumed rate, and your contribution joins it. Repeat until the plan ends.
- Step 1Start₹1 lakhwhat you already have
- Step 2Add every month₹10,000₹12 lakh over 10 years
- Step 3Growth₹7.51 lakhat an assumed 8% nominal rate
- Step 4End amount₹20.51 lakhstart + contributions + growth
You enter four of five things: starting balance, contribution, rate, length and end amount. The calculator finds the missing one.
Four questions, one calculator
Pick the unknown. The other fields stay the same.
- End amount₹20.51 lakhGiven the contribution, rate and length.
- Contribution₹26,117 a monthNeeded to reach ₹50 lakh instead.
- Return rate14.04%Nominal rate a plan would need to reach ₹30 lakh.
- Length of time17 years 7 monthsTime to reach ₹50.01 lakh, rounded up to a whole month.
Worked example
- Growth each period
i = (1 + j ÷ m)^(m ÷ f) − 1- Starting balance after n periods
P × (1 + i)^n- Contributions after n periods
C × (((1 + i)^n − 1) ÷ i)
- Pstarting balance ₹1,00,000
- Ccontribution each period ₹10,000
- jnominal annual rate 8%
- igrowth each period 0.67%
- nnumber of periods 120
- Starting balance grownP × (1 + i)^n₹2.22 lakh
- Contributions grownC × (((1 + i)^n − 1) ÷ i)₹18.29 lakh
- End amountsum of the two₹20.51 lakh
- Net interestend amount − start − contributions₹7.51 lakh
When contributions go in at the start of each period, the contribution part is multiplied by one more period of growth. When the rate is zero, nothing grows and the end amount is simply start plus contributions.
Where the money comes from
Over a long plan, growth can be a large share of the end amount. Over a short one, your own contributions dominate.
- Starting balance
- Contributions
- Interest
Settings that change the answer
Small settings move the result. Change one at a time to see which matters.
- Contribute at the start₹20.64 lakhInstead of ₹20.51 lakh at the end of each period.
- 5% yearly increase₹24.51 lakhContribution rises by 5% at the start of each year.
- 6% inflation₹11.46 lakhSame end amount, ₹20.51 lakh, shown in today’s money.
Compounding frequency
- Annual₹20.17 lakhEffective annual rate 8%.
- Quarterly₹20.45 lakhEffective annual rate 8.24%.
- Monthly₹20.51 lakhEffective annual rate 8.3%.
- Daily₹20.55 lakhEffective annual rate 8.33%.
What the result leaves out
- Changing returnsThe rate is held constant for the whole plan.
- TaxesNo tax is deducted from growth or withdrawals.
- FeesCharges and expense ratios are not subtracted.
- Real productsCredit dates and rounding in a real account may differ.
Related tools
This calculator handles any contribution schedule. Some common questions have a tool built around them.
For monthly mutual fund investing in rupees, the SIP calculator adds cost-of-delay and goal modes. For a single deposit, use the lumpsum calculator, and to plan several targets at once, the goal planner.
To measure a past investment’s growth rate, the CAGR calculator needs only the start and end values. The inflation calculator shows what an end amount is worth today.
Common mistakes
Mistake: Treating the return rate as a promise.
Instead: Use it as a scenario and try a lower figure as well.
Mistake: Comparing results from tools with different timing.
Instead: Check whether contributions go in at the start or end of each period.
Mistake: Reading a nominal rate as the yearly gain.
Instead: Look at the effective annual rate shown beside the result.
Mistake: Forgetting inflation on long plans.
Instead: Turn on the inflation field to see the amount in today’s money.
This calculator gives an illustration, not an investment recommendation. The rate and inflation are assumptions you choose, and it does not assess risk, taxes, fees or your circumstances.
Checking the method
A separate script recomputes every test case by formula and period by period, and reproduces OpenStax's published annuity example.
Read how we test our calculators, or browse more money calculators.