About this tool
Savings growth, explained
This savings growth calculator shows what a starting amount plus a monthly deposit becomes after a number of years. You fill in one sentence, and it tells you the final balance, how much of it is growth, what fees cost you and what the money is worth in today's terms.
How to use it
- 1Fill in the sentence: the amount after "Start with $", the monthly deposit, the yearly return and the number of years.
- 2Pick a preset such as Emergency fund, Retirement, College fund or One-time deposit, or set "Raise deposits each year", Compounding and "Deposit made" yourself.
- 3Add Yearly fees, "Tax on gains at withdrawal" and Inflation, then turn on "Show in today's money, after tax" to see the real figure.
- 4Read "You end up with", switch between Chart and Table, and use Copy link, Download CSV or Print or PDF to keep the plan.
How it works
How the balance is calculated
The calculator works month by month. The yearly rate is converted into the equivalent monthly rate for the compounding you choose, daily, monthly, quarterly or yearly. Each deposit arrives at the end of the month by default, or at the start with "Start of month". If you raise deposits each year, the monthly amount goes up by that percentage every new year.
Yearly fees are a percentage of the balance, taken a twelfth at a time after each month's growth, and the chart then adds a dashed "Without fees" line. Tax on gains is applied once, at withdrawal, to the final balance minus everything you put in. Inflation turns a result into today's money by dividing it by (1 + inflation) for each year.
With the starting values ($5,000, then $300 a month at 6% for 25 years, compounded monthly, no fees) you put in $95,000 and end up with about $230,200, so every $1 saved becomes about $2.42. At the default 2.5% inflation, that is about $124,200 in today's money. The tiles under the settings rerun the plan 2 points below and above your rate: about $167,800 at 4% and $322,000 at 8%.
Each month: Balance = Previous balance × (1 + r) × (1 − yearly fee)^(1/12) + Deposit, with r = (1 + annual rate / n)^(n / 12) − 1 and n the compounding periods a year
When to use it
Ways people use it
Set a savings target
Enter a Goal and the "Reach" tile tells you how many years and months it takes, with a Goal marker on the chart. Change the monthly deposit until the date suits you.
See the cost of waiting
Run the same plan over 25 years and then over 20. On the starting values, the five missing years leave about $155,200 instead of $230,200.
Measure what fund fees cost
Enter the yearly fee your fund charges. At 0.5% a year, the starting plan ends about $18,000 lower, because the fees also stop growing.
Share a plan
Copy link puts every setting in the address, so someone else opens exactly the same plan.
FAQ
Questions people ask
What is compound interest?
Compound interest is interest earned on both your original money and on the interest it has already earned. Each period, the gains are added to the balance and start earning too, which is why savings grow faster in later years than in early ones.
How often is interest compounded in this calculator?
Monthly by default, and you can switch to daily, quarterly or yearly. On the starting plan, daily compounding ends at about $230,800 and yearly at about $224,300, against $230,200 for monthly.
What return should I use?
Use the rate your account or fund actually offers, or a deliberately cautious estimate for investments whose returns vary. Investment returns are never guaranteed, which is why the tool also shows the result at 2 points below and above your rate.
Does the result include inflation and tax?
Only when you ask for it. The headline shows the nominal balance by default. Set Inflation and the tax on gains, then turn on "Show in today's money, after tax" to see what the money would buy. The tax is applied once, on the gains, as if you withdrew everything at the end.