Articles
Plain-English explanations of the math behind every calculator on CalcHub.
How to Calculate a Monthly Loan Payment
The standard amortization formula explained — what each variable means and how to verify any loan payment yourself.
How Mortgage Payments Are Calculated
What goes into a mortgage payment, how PITI works, and the 30-year vs. 15-year comparison with real numbers.
How Compound Interest Works
The formula, the difference between simple and compound interest, and why compounding frequency matters.
How to Calculate Monthly Savings to Reach a Goal
The future value of an annuity formula for savings planning, with worked examples and common benchmarks.
Understanding BMI: What It Measures and What It Doesn't
The WHO formula, the official categories, and the documented limitations of BMI as a health metric.
How Daily Calorie Needs Are Calculated
The Mifflin-St Jeor equation used by registered dietitians, and how activity multipliers work.
How to Calculate Your Macronutrient Targets
Calorie values per gram, USDA AMDR ranges, and how to convert percentages to gram targets.
How to Calculate Percentages: Four Common Problems Solved
Formulas for percent of, percent change, percent difference, and working backward from a percentage.
How Unit Conversion Works: The Factor Method
Dimensional analysis, exact NIST conversion factors, and why temperature conversion is different.
How Grades and GPA Are Calculated
Weighted average formulas, the 4.0 GPA scale, and how to calculate what you need on a final exam.
How Retirement Savings Are Calculated: Compound Growth and the 4% Rule
The future value of annuity formula, the Bengen 4% safe withdrawal rule, and S&P 500 historical return data.
How Debt Payoff Is Calculated: Minimum Payments, Interest, and Extra Payment Impact
The math behind payoff timelines, why minimum payments cost so much, and Federal Reserve APR data for 2024.
How Military PT Tests Work: Standards for All 6 Branches
Current official fitness test standards for Army, Navy, Marine Corps, Air Force, Space Force, and Coast Guard — events, scoring, and passing thresholds.
How VA Disability Ratings Work: The Combined Ratings Formula Explained
The 38 CFR § 4.25 whole person formula, worked examples, 2025 compensation rates, and how to apply for a rating.
How Military Pay Works: Base Pay, BAS, BAH, and the 2026 Pay Raise
A factual breakdown of the 3.8% raise effective January 1, 2026, how base pay is structured by grade and YOS, and what BAS and BAH actually cover.
How the Post-9/11 GI Bill Housing Allowance Works
How MHA is calculated from E-5 BAH rates, eligibility tiers per 38 U.S.C. § 3313, enrollment intensity rules, and the 2026 online-only flat rate.
How Military Retirement Works: High-3 vs. Blended Retirement System
The exact pension formulas under 37 U.S.C. § 1409 and § 356, BRS TSP contribution tiers, disability retirement, and the Survivor Benefit Plan.
How BAH Works: Basic Allowance for Housing Explained
How the DoD sets BAH rates annually, the 2026 5.4% increase, the dependency differential, and the rate protection rule under 37 U.S.C. § 403.
SCRA Interest Rate Cap: How the 6% Rule Works for Service Members
What debts qualify, how to invoke the cap, why the excess interest is forgiven (not deferred), and what happens if a lender violates 50 U.S.C. § 3937.
Military Clothing Allowance: FY2026 Rates by Branch and What They Cover
FY2026 initial and annual replacement allowance rates for all five DoD branches, sourced from DFAS CMA1 and CMA2, effective October 1, 2025.
How the TSP Works: BRS Matching, 2026 Contribution Limits, and Fund Performance
The exact BRS government matching formula, 2026 IRS contribution limits, vesting rules, and TSP fund performance data — sourced directly from TSP.gov and 37 U.S.C. § 354.