15-Year vs 30-Year Mortgage: Payment, Interest and Trade-offs
A shorter mortgage costs far less in interest but asks for a much higher monthly payment. A side-by-side example shows the size of both effects.
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Latest articles
Acres, Hectares and Square Miles: Land Area Units Compared
Land listings and maps use acres in some places and hectares in others. See how the units relate, how to convert them exactly, and how to avoid the squared-factor mistake.
Activity Multipliers: How to Pick the Right One for Your TDEE
The activity factor you choose changes your calorie estimate far more than the BMR equation does. Here is what each level means and how to avoid the usual overestimate.
How to Add and Subtract Fractions With Different Denominators
You cannot add 1/2 and 1/3 by adding the tops and bottoms. This guide shows the common-denominator method, with worked examples and mixed numbers.
APR vs APY: What the Two Rates Really Tell You
APR and APY are two ways to quote the same rate. One ignores compounding and one includes it, and mixing them up can make a worse deal look better.
APR vs Interest Rate: What the Difference Means for a Loan
A loan with the lower interest rate is not always the cheaper loan. The APR folds in certain fees so offers can be compared, and a worked example shows how.
BMI for Children and Teens: Why Percentiles Replace Cutoffs
A child's BMI is calculated like an adult's, but it is judged against other children of the same age and sex. Here is how percentiles work and what the bands mean.
Mifflin-St Jeor vs Harris-Benedict vs Katch-McArdle for BMR
Different BMR equations give different answers for the same person. Compare Mifflin-St Jeor, Harris-Benedict and Katch-McArdle on one set of numbers and see why they differ.
How to Calculate a Pay Raise and What It Is Worth After Inflation
A 3.5% raise on $52,000 is $1,820, but what does it buy? Learn the raise formulas, the effect of back-to-back raises, and how inflation changes the picture.
How to Calculate Time Slept and Sleep Efficiency
Time in bed and time asleep are not the same number. Learn to calculate both, handle the midnight crossing, and compute sleep efficiency by hand.
Calorie Deficit Math: Setting a Target and Estimating a Timeline
A daily calorie deficit converts into a predicted rate of weight loss with simple division. Here is the arithmetic, why the plan slows down over time, and where the limits are.
How Calories Burned Are Estimated: METs Explained
Most calorie-burn figures come from one short formula built on MET values. Learn how it works, how to use it by hand, and why the answer is an estimate.