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Long-form explainers and behind-the-math guides. Deeper than what fits on a calculator page.
Money math
Jun 15, 2026 · 9 min read
Should I Refinance My Mortgage in 2026?
The break-even formula, how to use the closing costs on a Loan Estimate, and when a refinance can still pay off.
Jun 15, 2026 · 9 min read
Cash-Out Refi vs HELOC vs Home Equity Loan
A cash-out refinance replaces your whole mortgage. A HELOC or home equity loan leaves it alone. One $50,000 example, worked three ways with the mortgage payment formula.
May 31, 2026 · 7 min read
How Mortgage Amortization Actually Works
In year one at current 7% rates, 87 percent of your payment is interest. Here is the math behind the front-loading and why it matters.
May 31, 2026 · 7 min read
The 1 Percent Rule for Rental Property
A handy screening shortcut that still works in some markets and breaks completely in others. The 2026 version.
May 31, 2026 · 8 min read
Social Security: Claiming 62 vs 67 vs 70
Claiming at 62 gives you 70 percent. Waiting until 70 gives you 124 percent. Here is the break-even math.
May 31, 2026 · 6 min read
The Credit Card Payoff Math Nobody Shows You
Why a shrinking minimum payment drags on for decades, and what a fixed payment does instead: $5,000 at 22 percent APR, $300 a month, paid off in 21 months.
Health and body
May 31, 2026 · 7 min read
BMI vs Body Composition
BMI was invented in 1832 to study populations, not individuals. What it measures, where it fails, and which methods work better.
May 31, 2026 · 7 min read
The Navy Body Fat Formula Explained
A tape measure and the right formula can match a $200 DEXA scan within a few percentage points. Here is why.
Nutrition and meal planning
Oct 8, 2026 · 17 min read
Your Calorie Estimate Is a Starting Point
Mifflin-St Jeor plus the TDEE page's activity factors. How to check the result and change the offset you type, without a promised rate of weight change.
Oct 8, 2026 · 23 min read
Budget High-Protein Meal Prep: Cost per Gram
A family-of-4 method: adult protein grams, example prices divided by grams, a Sunday batch, a merged list, and the USDA food-plan footnote.
Around the house
Oct 3, 2026 · 10 min read
How Many Gallons of Paint for a 12x12 Room
At the paint calculator's defaults a 12x12 room is 2.06 gallons, so you buy 3. The same formula for 10x10, 10x12, and 12x14.
Oct 3, 2026 · 9 min read
Baking Pan Conversion Chart
9x13 to a 9-inch round is a factor of 0.54. 8x8 to 9x13 is 1.83. The chart is the pan converter's floor-area math.
Oct 3, 2026 · 10 min read
Recipe Halving, Doubling, and Thirding Chart
Half of 3/4 cup is 3/8 cup (6 tablespoons). The chart shows what the recipe scaler prints, including the fractions it snaps.
May 31, 2026 · 7 min read
Cooking Measurement Myths That Ruin Recipes
A cup is not a cup. A stick of butter is not always 8 tablespoons. Your flour weighs differently depending on how you scooped it.
May 31, 2026 · 7 min read
How to Read a Paint Label and Calculate Coverage
What the numbers on a paint can actually mean, why stated coverage is optimistic, and how many gallons you really need.
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