MyCalcsWorld guides
Clear walkthroughs for everyday math
25 guides written by the MyCalcsWorld editorial team. Each one explains the idea, shows the formula, walks through a worked example with checked numbers, lists common mistakes, and links to the calculators that do the arithmetic for you.
Loans & mortgages
How Mortgage Payments and Amortization Work
See how a fixed-rate mortgage payment is built, why early payments are mostly interest, and what extra payments or a shorter term really change.
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EMI vs Flat-Rate Interest Explained
Learn why a flat-rate loan costs more than the same quoted reducing-balance rate, how to convert flat to an equivalent rate, and how to compare offers fairly.
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A Loan Comparison Checklist: Rate, Fees, APR and Total Cost
A practical checklist for comparing loan offers, with a worked example showing why a lower rate with a fee can cost the same as a higher rate with none over five years.
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Loan EMI Explained — Payment, Interest & Tenure
What EMI means, how the amortizing formula works, how tenure and rate change your payment, and a worked example you can mirror in the EMI calculator.
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Mortgage Payments — P&I, Term Length & Total Interest
How fixed-rate mortgage principal-and-interest payments work, what a longer term costs in interest, and a worked 30-year example.
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Saving & investing
SIP and Compounding: What Regular Investing Looks Like Over Time
Understand how monthly investing compounds, what the future-value formula says, and why starting early beats investing more later — with checked numbers.
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Compound Interest vs Simple Interest: The Real Difference
Compare simple, annual-compound and monthly-compound growth side by side, learn APR vs APY, and use the Rule of 72 with correct, checked numbers.
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Retirement Savings Math: The Basics
Learn the target-number approach to retirement, how much a monthly contribution can grow over 25, 30 and 35 years, and what the 4% rule of thumb does and does not mean.
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Inflation and Real Returns: Why Nominal Numbers Mislead
Understand inflation, purchasing power and the real rate of return with the exact Fisher formula and checked examples over 10 and 20 years.
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Compound Interest & Daily Compounding — How Growth Stacks
Understand compound interest vs daily compounding, how to read future value, common rate mistakes, and a worked savings example — then open the live calculators.
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Debt
How Credit Card Interest and Minimum Payments Work
See how card interest accrues, why paying only the minimum can take over a decade, and how a fixed payment changes the payoff time — with checked numbers.
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How to Pay Off Debt Faster: Avalanche vs Snowball
Compare the avalanche and snowball methods with a four-debt simulation, see the interest difference, and learn when each approach makes sense.
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Everyday math
Percentage Change vs Percentage Points
Clear rules for percent change, percentage points, reverse percentages and chained changes, with worked examples that show why +50% then −50% does not return to zero.
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Sales Tax, VAT and GST: How They Work (Conceptually)
Understand sales tax versus VAT and GST, how to add and remove tax correctly, and why a tax-inclusive price is not 'price minus the rate'.
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Tipping and Splitting a Bill: The Math and the Etiquette
Calculate tips before or after tax, split a bill evenly or by item, handle rounding fairly, and understand why tipping customs differ — with checked numbers.
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Unit Conversion Pitfalls: Metric, Imperial and Common Mistakes
Exact conversion factors, US versus imperial units, temperature and fuel-economy traps, and a checklist that prevents the most expensive unit errors.
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Date and Time Calculations: Leap Years, Business Days and Time Zones
Count days between dates, add days or months, handle business days and ISO weeks, and avoid time-zone and leap-year mistakes — with worked examples.
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Fuel Cost and Fuel Efficiency: Formulas, Conversions and Trip Math
Calculate trip fuel cost, cost per kilometre or mile, convert between mpg and L/100 km, and compare petrol or diesel with electric charging using clear formulas.
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Percentage, Tip & Tax — Everyday Percent Math
Percent of a number, tip on a bill, GST/VAT inclusive vs exclusive, and worked examples you can replay in the calculators.
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Health numbers
BMI: What the Number Means and What It Misses
How BMI is calculated in metric and imperial units, what the standard adult categories are, and why it is only a screening number — with caveats and alternatives.
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Calories, TDEE and Macros: The Basics (With Caveats)
How BMR and TDEE are estimated with the Mifflin–St Jeor equation, how activity multipliers work, and how to turn a calorie target into protein, carb and fat grams.
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How a Pregnancy Due Date Is Calculated
Naegele's rule, cycle-length adjustments, gestational age in weeks and days, and why an estimated due date is a range rather than a promise.
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BMI Basics — What the Number Means (and Doesn’t)
How body mass index is calculated from height and weight, how to interpret ranges, common pitfalls, and when to talk to a clinician.
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Home projects
Education
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