About Us

numCruncher is a collection of free, accurate online calculators built for people who want fast, trustworthy answers to everyday money and health questions — without the clutter, the sign-up walls, or the upsells. It started from a simple frustration: most calculator sites give you a number and nothing else, leaving you to wonder whether to trust it or what it actually means. We set out to build tools that not only compute the right answer but explain the reasoning behind it, so you leave understanding your mortgage, your debt payoff plan, or your calorie target — not just looking at it.

Who's Behind numCruncher

numCruncher is built and maintained by Matt Dougherty, based in Greenville, South Carolina. Matt started numCruncher after growing frustrated with other online calculator sites — many of them out of date, and most of them happy to hand you a number with no explanation. numCruncher is meant to be the opposite: the goal is to help you actually understand the number, not just see it. Every calculator and guide on the site is written, tested against reference cases, and reviewed by Matt personally before it's published. Have a correction, a question, or a calculator to request? Reach out through the contact page — every message is read and answered personally.

What We Cover

Our calculators span four areas. Home & Mortgage includes mortgage payments and amortization, refinancing, affordability, rent versus buy, PMI, and home equity. Auto covers loans, leasing versus buying, affordability, total cost of ownership, and the gas-versus-electric break-even. Finance & Investing covers compound interest, debt payoff strategies, and retirement planning. Health & Fitness covers BMI, body-fat percentage, calorie and BMR needs, and macronutrient targets. Each tool pairs the calculator with an in-depth written guide, worked examples, and answers to the questions people most commonly ask.

How We Build Our Calculators

Accuracy is the foundation of everything here. Our financial tools use standard, published formulas — loan amortization, compound-interest equations, and widely used lender benchmarks such as the 28/36 debt-to-income rule and the 20/4/10 guideline for car buying. Our fitness tools rely on established, peer-reviewed equations, including Mifflin–St Jeor for basal metabolic rate and the U.S. Navy circumference method for estimating body fat. Before a calculator is published, we test it against known reference cases and worked examples to confirm the math matches what a bank, financial planner, or clinician would calculate. When guidelines or best practices change, we revisit the affected tools and their explanations.

Honest, Independent Results

We keep things simple: free tools, transparent math, and no sponsored recommendations baked into the results. When a calculator tells you what a loan costs or which payoff strategy is cheaper, that answer comes from the formula, not from an advertiser. The site is supported by standard display advertising, which is kept separate from the calculations themselves — ads never influence the numbers a tool produces or the guidance we write.

Private by Design

Every calculation runs entirely in your browser. We don't store your inputs, send them to a server, or require you to create an account. The figures you enter — your income, your loan balance, your weight — stay on your screen and disappear when you close the tab. You can read more in our privacy policy.

A Note on Our Guidance

The calculators and articles on numCruncher are intended for general educational purposes. They're a strong starting point for understanding your options, but they can't account for every detail of your personal situation. For decisions with significant financial or health consequences, we encourage you to confirm the numbers with a qualified professional — a lender, financial advisor, or healthcare provider — who can advise you directly.

Get in Touch

Have a suggestion, found a bug, or want to request a new calculator? Send us a message — we read everything, and many of our tools exist because a reader asked for them.