MSO Calc Guides
Pair each guide with its calculator. Read the explanation, then run your own numbers. Fifty-three topics across money, health, math, conversion and everyday calculations.
The Answer, Then the Reason Behind It
A calculator hands you a number. A guide tells you what that number means and what to do about it. Your mortgage payment is $2,547 per month. Fine, but should you take a 15-year loan at a lower rate or a 30-year and invest the difference? Your BMI says 27. What does that mean if you lift weights twice a week? Your salary offer is $72,000. What is that hourly, after tax, and is it competitive in your city? The calculators on this site give you the numbers in two seconds. The guides walk you through what to do with them.
Decisions These Guides Help You Make
- Buying a home. Whether to put 20% down, when refinancing pays off, how PMI works, what the amortization curve looks like in year three versus year twenty-five.
- Managing your weight. Why BMI categories miss athletes and older adults, how Mifflin-St Jeor calculates your maintenance calories, where the 8-glasses-of-water myth came from and what to drink instead.
- Planning retirement. The 4% rule, the difference between nominal and real returns, why starting at 25 with $200 a month beats starting at 35 with $400 a month.
- Negotiating a salary. Converting any pay rate to any other, valuing benefits in dollars, when to push back on an offer and what BLS data says about your role.
- Math you forgot from school. Percentages, triangle trigonometry, fractions, GCF and LCM, quadratic equations. Plain explanations, worked examples, and the formulas you can copy into a spreadsheet.
- Unit conversion with context. Why a US gallon and a UK gallon differ by 20%, what the difference between mass and weight means in physics versus everyday speech, the history behind why three temperature scales coexist.
How to Read These Guides
Each guide opens with the question you came for and answers it in the first two paragraphs. The middle of the article walks through the math with concrete numbers and a worked example. The bottom holds the FAQ that covers the questions people ask after they have read the body. If you want the calculator alone, the "Open Calculator" link at the top of every guide takes you there. If you want only the answer, the first 200 words usually contain it.
Sources We Cite
The guides draw figures and formulas from the original sources rather than rephrasing them from other websites. Mortgage rules quote the CFPB and HUD. Health figures come from the WHO, the US Institute of Medicine, NHANES surveys and peer-reviewed nutrition journals. Tax rules cite the IRS. Salary data references BLS Occupational Employment Statistics and OECD wage tables. When a guide makes a numeric claim, the link at the end of the relevant sentence takes you to the source.