EVERYDAY
Clothing Size Converter Guide
Complete guide to international clothing sizes: why US, UK and EU sizing differ, online-ordering and shoe-size examples, and why fit varies after converting.
Calculator Guides
In-depth guides explaining how each calculation works, published by the CalcPro.
Showing all guides
MATH
Prime Number Guide
Complete guide to prime numbers: what a prime number is, how to test for primality, prime factorisation, the Sieve of Eratosthenes, and why primes matter.
EVERYDAY
Cooking Measurement Converter Guide
Complete guide to cooking measurement conversions: cups to ml, tablespoons to grams, ounces to grams, and dry vs liquid measuring. Includes printable.
MATH
Matrix Calculator Guide
Guide to 2×2 matrix operations: addition and subtraction, why multiplication is not element-by-element, the determinant, and where 2×2 matrices are used.
EVERYDAY
Time Zone Guide
Complete guide to time zones: why conversion is more than adding an offset, scheduling international meetings, half-hour offsets and countries without DST.
EVERYDAY
Travel Time Guide
Learn how to accurately estimate travel time: average speed calculation, traffic and rest stops, road trip planning tips, and how to calculate ETA for any.
EVERYDAY
Electricity Bill Guide
Complete guide to electricity bills: how kWh usage is calculated, which appliances use the most power, how to read your bill, and 15 proven ways to reduce.
MATH
Rounding Guide
Complete guide to rounding numbers: decimal places, significant figures, standard, floor and ceiling modes, banker's rounding, and rounding vs truncating.
HEALTH
Steps to Calories Guide
Learn exactly how walking steps convert to calories burned. Covers stride length, MET values for walking, the 10,000 steps rule, and how body weight.
MATH
Volume Calculator Guide
Complete guide to volume calculations for every 3D shape: cube, sphere, cylinder, cone, pyramid, and prism. Includes formulas, derivations, unit.
FINANCE
GST Guide
Complete guide to GST: adding vs extracting GST, worked examples for Australia (10%) and India (18% on services), and how GST compares with VAT and sales tax.
FINANCE
ROI Calculator Guide
Complete guide to return on investment: the ROI formula, property and marketing campaign examples, and what ROI doesn't tell you when comparing investments.
FINANCE
Commission Calculator Guide
How sales commission works: common commission structures, worked examples for a property agent and a SaaS account executive, and commission rate vs margin.
MATH
Exponent Guide
Guide to exponents: positive, negative, zero and fractional exponents, a compound growth example, scientific notation, and why huge exponents overflow.
EVERYDAY
Speed Distance Time Guide
Complete guide to the speed-distance-time formula: calculating speed, distance and time, worked journey examples, and why a return trip's average speed differs.
FINANCE
Interest Rate Guide
Complete guide to interest rates: APR vs AER, fixed vs variable rates, how central bank rates affect loans, how to find the best savings rate, and real.
FINANCE
Break-Even Analysis Guide
Guide to break-even analysis: the break-even formula, contribution margin, fixed vs variable costs, margin of safety, and where the analysis falls short.
FINANCE
Profit & Loss Guide
Complete guide to profit and loss: profit formula, gross margin vs markup, how to improve profit margin, P&L statement basics, and common profit mistakes.
HEALTH
Macro Calculator Guide
Complete guide to macronutrients: how to calculate macros for your goal (weight loss, muscle gain, maintenance), IIFYM explained, protein requirements.
EVERYDAY
Unit Conversion Guide
Complete guide to unit conversion: metric vs imperial system, how to convert length, weight, temperature, volume, and area. Includes conversion factors.
HEALTH
Sleep Cycle Guide
Guide to sleep cycles: how the roughly 90-minute cycle works, REM vs deep sleep, planning bedtime around an alarm, and why 90 minutes is only an average.
EVERYDAY
Currency Conversion Guide
Complete guide to currency exchange: how exchange rates work, bid/ask spread, how to get the best exchange rate, forex basics, and common currency pairs.
MATH
Logarithm Guide
Complete guide to logarithms: what a logarithm is, log base 10 vs natural log, log laws, how to solve log equations, and how logarithms appear in science.
MATH
Ratio Calculator Guide
Complete guide to ratios and proportions: how to simplify a ratio, how to solve proportions, ratio vs fraction vs percentage, and real-world ratio.
MATH
Average Calculator Guide
Learn the difference between mean, median and mode, with the formulas, exam-score and monthly-expense examples, and why the mean and median can differ.
HEALTH
Pregnancy Due Date Guide
Complete pregnancy due date guide: how EDD is calculated from LMP, Naegele's rule, IVF due dates, trimester milestones, and why due dates are estimates.
EVERYDAY
Fuel Cost Guide
Learn how to calculate fuel cost for any journey. Covers mpg vs L/100km, how fuel prices affect trip cost, fuel-efficient driving tips, and how to compare.
MATH
Area Calculator Guide
Complete guide to calculating area for every common shape: square, rectangle, triangle, circle, trapezoid, parallelogram, and ellipse. Includes formulas.
HEALTH
Water Intake Guide
Complete guide to daily water intake: the 8 glasses myth debunked, how body weight, climate, and activity affect hydration needs, signs of dehydration.
FINANCE
Inflation Guide
Guide to inflation: the formula, real vs nominal value, how inflation erodes savings, a retirement planning example, and why CPI, RPI and PCE differ.
FINANCE
Credit Card Payoff Guide
Guide to paying off credit card debt: the minimum payment trap, minimum vs fixed payments, avalanche vs snowball methods, and when balance transfers help.
FINANCE
Budget Calculator Guide
Step-by-step guide to building a personal monthly budget: the 50/30/20 rule, tracking income and expenses, setting savings targets, and common budgeting.
MATH
Square Root Guide
Complete guide to square roots: what a square root means, a room side-length example, cube roots, and why negative numbers have no real square root.
HEALTH
Calorie Burn Guide
Learn how exercise burns calories: MET values explained, running vs walking, desk work vs strength training, and why MET-based estimates have limits.
HEALTH
Ideal Weight Guide
Learn how ideal body weight is estimated from height and sex, what three common formulas say, what the result range means, and why it's a guide, not a target.
FINANCE
EMI Guide
Complete guide to EMI (equated monthly instalment): the PMT formula, how amortisation works, how to reduce your EMI, prepayment vs longer tenure, and EMI.
FINANCE
Discount Calculator Guide
Learn how to calculate percentage discounts, sale prices, and original prices. Covers percentage off formulas, stacked discounts, and how retailers use.
EVERYDAY
Date Difference Guide
Learn how to calculate the exact number of days, weeks, and months between two dates. Covers business day counting, leap years, and practical date math.
MATH
Algebra Calculator Guide
Guide to solving algebra equations: linear and quadratic equations, worked real-life examples, and what a negative discriminant means.
HEALTH
Heart Rate Guide
Guide to heart rate for exercise: why 220 minus age is only an estimate, the five training zones, Zone 2 training, and how to measure your heart rate.
FINANCE
Simple Interest Guide
Complete guide to simple interest: the SI formula, worked examples, simple vs compound interest comparison, where simple interest is used in real life.
FINANCE
Investment Growth Guide
Learn how to project investment growth with compound returns and regular contributions, why starting early matters, and how return assumptions change results.
HEALTH
Body Fat Calculator Guide
Complete guide to body fat percentage: Navy method formula, healthy body fat ranges for men and women, how to measure body fat at home, and tips to reduce.
FINANCE
Salary Calculator Guide
Learn how to convert between hourly, weekly, monthly and annual pay, with job-offer and freelance examples, gross vs net pay, and salary sacrifice.
MATH
Fraction Calculator Guide
Complete guide to fraction arithmetic: how to add, subtract, multiply and divide fractions, with recipe and material-cut examples and why simplifying matters.
HEALTH
BMI for Children Guide
Complete guide to BMI for children aged 2–19: how pediatric BMI percentile works, CDC growth chart interpretation, healthy weight ranges, and childhood.
FINANCE
Savings Calculator Guide
Complete guide to growing your savings: compound interest, high-yield accounts, the 50/30/20 rule, goal-based saving, emergency funds and automating savings.
FINANCE
Retirement Planning Guide
Complete retirement planning guide: the 4% rule, 25x rule, how much to save by age, 401k vs IRA comparison, compound growth in retirement, and FIRE.
MATH
Scientific Calculator Guide
Complete guide to using a scientific calculator: trigonometry functions (sin, cos, tan), logarithms, powers and roots, order of operations, and common.
EVERYDAY
Tip Calculator Guide
Complete tipping guide: tipping on pre-tax vs post-tax totals, splitting a restaurant bill, tipping norms by country, and when service charge is included.
EVERYDAY
Age Calculator Guide
Learn how to calculate exact age in years, months and days, how to find an age on a past or future date, and where leap years cause confusion.
FINANCE
Income Tax Guide
Complete income tax guide: how tax brackets work, marginal vs effective tax rate, standard deduction, common deductions and credits, and legal strategies.
FINANCE
Loan Calculator Guide
Guide to loans: the payment formula, how amortisation works, APR vs interest rate, secured vs unsecured loans, loan terms, extra payments and red flags.
MATH
Percentage Calculator Guide
Complete guide to percentages: the percentage formula, percentage of a number, percentage increase and decrease, and finding the original value before a change.
FINANCE
Compound Interest Guide
Complete guide to compound interest: the formula explained, compounding frequency (daily vs monthly vs annual), Rule of 72, compound vs simple interest.
HEALTH
BMI Calculator Guide
Guide to Body Mass Index: the BMI formula, WHO categories, the limitations of BMI, BMI vs body fat, and how to interpret your score.
FINANCE
Mortgage Calculator Guide
Mortgage guide: the monthly payment formula, how interest rates change the cost, 15-year vs 30-year loans, PMI, down payment strategy and amortization.
REAL ESTATE
Rent vs Buy: How to Know When Buying Actually Wins
A complete, numbers-first guide to the rent vs buy decision: the formula, the breakeven year, real worked examples, and 15 FAQs — plus a free calculator to run your own numbers.
REAL ESTATE
Rental Yield Explained: Gross vs Net (And Why the Gap Matters)
Rental yield explained: the gross and net formulas, what counts as a good yield, and why two properties with the same gross yield can have very different net returns.
REAL ESTATE
Cap Rate Explained: The Unlevered Return Every Investor Should Know
Cap rate explained in plain terms: the formula, what counts as NOI, what a good cap rate looks like, and how it differs from cash-on-cash return — with worked examples.
REAL ESTATE
Cash-on-Cash Return Explained: What Your Cash Is Really Earning
Cash-on-cash return explained: the formula, how leverage changes it, what counts as cash invested, and how it differs from cap rate — with worked examples.
REAL ESTATE
How Much Down Payment Do You Really Need?
The 20% down payment rule is mostly a myth. Here's what loan programs actually require, how PMI works, and how to build a realistic savings timeline — with a free calculator.
REAL ESTATE
Closing Costs Explained: Every Fee You'll Actually Pay
A full breakdown of home closing costs — lender fees, title insurance, prepaid interest, transfer taxes — with real dollar examples and a free calculator to itemize your own.
REAL ESTATE
How Property Tax Actually Works
Property tax explained in plain terms: how assessed value differs from market value, what a mill rate is, which exemptions you can claim, and how to estimate your bill.
REAL ESTATE
House Flipping Math: The 70% Rule and Real Profit Margins
How to actually underwrite a house flip: the 70% rule, ARV, rehab budgets, holding costs, and financing — with worked examples and a free profit calculator.
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