Financial Disclaimer
CompoundCalc publishes mathematics, not advice. This page explains precisely where the maths stops being useful, because a compound interest projection is one of the easiest numbers in finance to over-trust.
A calculator that says “$1,187,000 in 30 years” is not making a prediction — it is telling you what happens if a fixed rate you chose repeats itself every single year without a break, which is something no real investment has ever done.
Educational use only
Everything on compoundcalc.com is published for general education and scenario comparison. It is not personal financial advice, investment advice, tax advice, pension advice, mortgage advice or legal advice, and it is not a personal recommendation. CompoundCalc is not authorised or regulated by any financial regulator, and does not sell, arrange or promote financial products.
What the models assume — and where reality departs
| The calculator assumes | Reality |
|---|---|
| A constant annual return, every year | Markets deliver an average made of very good and very bad years. Two portfolios with the same average can end far apart depending on the order of returns. |
| Contributions never stop or change | Job changes, illness, children and rate rises interrupt contributions. A three-year gap early on costs more than the same gap late. |
| No taxes | Dividends, interest and gains may be taxable depending on your country and account type. |
| No fees | Platform fees, fund charges, spreads and currency conversion all reduce the compounding rate. A 0.9% annual fee is roughly an eighth of a 7% return, every year. |
| Nominal money | Inflation reduces what the final figure buys. See compound interest vs inflation and retirement in today's dollars. |
| Interest is reinvested in full | Cash sitting in an account between deposits, or dividends taken as income, breaks the compounding chain. |
Because of this, treat any output as the answer to a what if question, not as a forecast. Running the same scenario at a lower rate is usually more informative than running it once at an optimistic one.
Past performance
Historical average returns are often used as the input to these tools. Past performance is not a reliable indicator of future results. The value of investments can fall as well as rise, and you may get back less than you put in.
No personalised recommendation
The site does not know your income, debts, tax position, time horizon, dependants, health, employment security or risk tolerance — all of which change what a sensible plan looks like. Two people can enter identical numbers and need opposite decisions. For anything that materially affects your finances, speak to a qualified, regulated professional in your own country.
Accuracy and corrections
Calculator outputs are checked against independently computed reference values before release, and worked examples printed in the guides are recomputed from the same engine that powers the tools. Errors are still possible. If a number here looks wrong, report it to contact@compoundcalc.com; how corrections are handled is described in the editorial policy.
Jurisdiction and product rules
Some pages reference country-specific wrappers such as ISAs and pensions. Contribution limits, tax treatment and access rules change over time and differ by country. Always confirm current rules with the relevant tax authority or provider before acting.
Advertising
This site is funded by advertising. Ads are labelled and served by third-party networks; their presence is not an endorsement of any advertiser or product, and advertisers have no input into the guides or the calculators. Methodology and legal pages carry no advertising at all.
Liability
To the fullest extent permitted by law, CompoundCalc accepts no liability for any loss or damage arising from use of, or reliance on, this website. Your use of the site and any decision you make afterwards is at your own risk. This does not affect statutory rights that cannot lawfully be excluded.