The LedgerLab Blog
Plain-language guides to everyday money math.
Short, educational articles that explain the ideas behind our calculators — with worked examples, large illustrations and no jargon.
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InflationInflation and purchasing power: why a dollar buys less over time
Inflation quietly compounds too. Here is how to think about what your money will really buy in the future.
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Savings & growthThe Rule of 72, explained
A quick mental shortcut for estimating how long money takes to double — and where the shortcut starts to drift from the exact answer.
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Savings & growthCAGR vs. average return: which number tells the truth?
A 50% gain followed by a 50% loss does not leave you flat. CAGR captures the path that a simple average misses.
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Savings & growthThe math behind a savings goal
Working backwards from a target date: how much to set aside each month when interest helps (or does not).
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Everyday moneyBreak-even math for side projects
Fixed costs, variable costs and contribution margin — a clear way to know when a project starts covering itself.
Articles are for educational purposes only and are not financial advice. Read the full disclaimer.