Tools
Cross-cutting
Browse topics
Compound interest
Returns that earn returns — how time turns a rate into an exponential path, and what still breaks the fairy tale.
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⌛Time value of money
A dollar today is not a dollar in ten years — discounting, present value and why waiting has a price.
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⚖️Opportunity cost
Every choice spends an alternative future — how to price the path you did not take without freezing decisions.
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🔢Rule of 72
A mental model for doubling time: divide 72 by the rate — useful, approximate, and easy to abuse.
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🌡️Nominal vs real returns
Headline growth lies when prices rise — how to read returns after inflation eats purchasing power.
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Contributions vs rate vs time
Early on, deposits dominate; later, rate and time do — how the three levers trade places across a life.
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📉Fee drag
A one-percent fee is not one percent of outcomes — compounding makes costs exponential too.
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🧾Tax drag
Taxes change which return compounds — wrappers, location and realisation timing as first-class levers.
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♻️Reinvestment
Cash paid out only compounds if you put it back — dividends, coupons and the discipline of not spending yield.
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📅Dollar-cost averaging
Fixed buys on a schedule — what DCA really changes (behaviour and timing risk) and what it does not guarantee.
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Early start advantage
Starting small early often beats starting large later — the asymmetric gift of unused decades.
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🏃Late catch-up saving
When the runway is short, contribution size and fee hygiene matter more than clever forecasts.
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🎢Sequence of returns risk
The same average return can fund or break a plan depending on the order of good and bad years.
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🏛️Multi-decade & legacy horizons
When the goal outlives one career, governance, fees and purpose matter as much as the rate.
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Cash & high-yield savings
Cash is an option on patience — when high nominal rates revive interest, and when inflation still wins.
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🧱Bonds as ballast
Bonds dampen equity storms and pay a yield — duration, credit and inflation decide whether they help.
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🌍Broad equity index
Owning the market’s productive capital cheaply — the default long-horizon compounding vehicle in modern advice.
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🤝Employer match
A match is an instant return on your contribution — often the highest “rate” available without market risk.
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Consistency as a habit
The schedule you keep beats the forecast you admire — habits that keep contributions alive through boredom.
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🛒Lifestyle creep
Raises that vanish into nicer defaults — how creeping spend steals the contribution lever compounding needs.
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😱Panic selling
Selling the engine after a crash realises sequence damage — why behaviour gaps show up in real investor returns.
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📡 Now
3Cash renaissance (2020s)
After near-zero rates, cash yields returned — how to use them without abandoning long-horizon compounding.
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🔥FIRE variants
Financial independence maths under a microscope — savings rates, safe withdrawal debates and lifestyle design.
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📱Auto-invest apps
Defaults, round-ups and target-date rails — how apps industrialise contributions, and where fees still hide.
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