The QuickCalculator Blog
Guides that explain the formulas behind the numbers.
What We Write About
New articles appear regularly. We cover the math behind our calculators, practical everyday finance, health metrics, and handy web tips — all written to be read in five minutes.
How BMI Is Calculated (and What It Actually Tells You)
The formula behind body mass index, why it uses height squared, and the limits you should know about before trusting the number.
Discounts and Sale Prices: How Retailers Make You Pay More
Stacked discounts, BOGO offers, and anchor pricing — the tactics that make a deal look better than it is.
How Mortgages Actually Work (Beyond the Rate)
Principal, interest, escrow, and why the total cost of a mortgage is very different from the sticker price.
Fixed vs. Variable Rates: Which Loan Makes Sense for You
The trade-off between predictability and potential savings, and when each type of rate is the right choice.
What Your Loan Payment Actually Covers
Principal, interest, and why your first payments barely touch the balance — an explainer on amortization without the jargon.
Saving for Retirement: The Math Behind the Number
The 4% rule, employer match, fund fees, and why starting ten years earlier matters more than contributing more.
Understanding Compound Interest in Five Minutes
A plain-English walkthrough of the formula that quietly governs savings, debt, and retirement — with a worked example.
Understanding Your Paycheck: Where the Money Goes
Gross vs. net, FICA, pre-tax vs. post-tax deductions, and why your first paycheck was smaller than expected.
How Much House Can You Actually Afford?
The 28/36 rule, why gross income misleads, and the costs that pre-approval calculators ignore.
Percentages in Real Life: Three Questions, One Method
Almost every percentage problem is one of three shapes. Recognize them and the math becomes trivial.
Calories Explained: BMR, TDEE, and the 500-Calorie Rule
What a calorie actually is, how your body burns them, and where the 3,500-calorie-per-pound figure comes from.
Body Fat Percentage Explained
Essential vs. storage fat, healthy ranges, and how the US Navy method compares to DEXA.
Pregnancy Timeline Explained: Why 40 Weeks Starts Before Conception
Gestational age, Naegele’s rule, trimesters, and how to read a due date without confusion.
Sleep and Your Health: How Much Is Actually Enough
Sleep debt, recovery sleep, and what the research says about hours, quality, and long-term risk.
The 10,000-Step Myth (and What the Research Actually Says)
Where the 10,000-step goal came from, why it isn’t scientific, and how to set a step target that fits you.
Unit Conversion Mistakes That Actually Cost People Money
Fluid ounces vs. ounces, US vs. UK gallons, and other conversion traps that trip up even careful people.
Understanding GPA: Weighted, Unweighted, and What Colleges See
How grade point average is actually calculated, why two 3.5s can mean different things, and how to raise a low one.
Mental Math Tricks Worth Knowing
A handful of shortcuts that make quick arithmetic in your head faster than reaching for a calculator.