About Calc.Cards

Last updated 2026-05-18

Calc.Cards is a free online calculator site. It exists to answer the one-number question a person actually has — what will my mortgage payment be, how many calories should I eat, how much concrete does this slab need — and to show the math behind that number so you can trust it.

Today the site publishes 395 calculators across 19 domains: finance, real estate, construction, health, fitness, cooking, science, math, education, business, automotive, energy, conversion, pets, pregnancy, tech, time, travel, and a small section of meme calculators built for trivia debates rather than life decisions. Every tool is free in the browser, no account required.

Who runs Calc.Cards

Calc.Cards is built and operated by Wilcoe, an independent studio that builds calculator and decision-support tooling. Wilcoe is the publisher of record, handles editorial and engineering, and is the entity behind the copyright notice at the bottom of every page.

The team is small and works directly. You can reach us at hello@calc.cards — corrections, partnership inquiries, and bug reports all land in the same inbox and are answered by a person.

How our calculators are built

Every calculator on the site follows the same four-step pipeline before it ships:

Source the formula.We start from the authoritative formula or definition, not a generic blog post. Mortgage math comes from the standard amortization formula and the Consumer Financial Protection Bureau's consumer guidance. Calorie targets use the Mifflin-St Jeor equation. Concrete-slab volume uses the standard cubic-yard conversion. For finance and health calculators we cite the primary source on the page.
Build the widget. The interactive calculator is written once, runs entirely in your browser, and never sends your inputs to a server. We test the math against known benchmarks (a published example, a worked-out textbook problem, or an official agency table) before the tool goes live.
Write the article. Each page is paired with a 1,000– 4,500 word editorial that explains what the calculator does, walks through the formula, gives a worked example with real numbers, and covers the practical traps a first-time user runs into. The goal is that you can follow the math without using the widget — the widget just does it faster.
Editorial review.Before a calculator ships, an editor reviews the formula implementation against the cited source, checks the worked example end-to-end, and runs the page's FAQ against common-sense questions a non-expert would ask. The byline on every page ("Reviewed by Calc.Cards Editorial Team") is the editorial sign-off; the "Last updated" date is when that review last re-ran.

How we use AI

We use AI assistance in the drafting phase the same way a small newsroom uses a research assistant: to pull together candidate phrasings, surface adjacent questions, and structure the article. Every page is then edited by a human, has its math verified against a primary source, and carries the editorial sign-off.

AI is never the source of authority for a calculation. The formula, the numeric thresholds (BMI cutoffs, IRS contribution limits, FHA loan limits, conventional PMI rules, etc.), and the cited references on each page come from the underlying agency, journal, or textbook — not the model.

Accuracy and what these tools are not

We aim for every calculator to be accurate to the input given, and we show our work so you can verify it. We also expect — and you should expect — that the calculators on this site are educational and decision-support tools, not professional advice.

Finance calculators give estimates. A mortgage payment, a refinance break-even, or a retirement projection here is a planning input, not a quote and not financial advice. Talk to a licensed mortgage professional, CPA, or fiduciary advisor before making a decision.
Health calculators give population-level estimates from published formulas (Mifflin-St Jeor, Watson, CDC pediatric growth charts, etc.). They don't know your medical history. Talk to a clinician before acting on a result.
Construction calculators give material estimates from clean inputs. Real job sites have waste, irregular geometry, and code requirements we can't see — always pad and always check local code.

If you find an error in a formula, a worked example, or a cited number, please email hello@calc.cards with the calculator URL and what looks wrong. We treat corrections as a priority and re-publish with an updated date.

How Calc.Cards makes money

The free web calculators stay free. We support the site through four revenue streams, in roughly the order they exist on the page:

Advertising. We use Google AdSense to serve display and text ads alongside editorial content. Ads are labeled and kept out of the calculator widget itself so they never interfere with the math.
AI calculator skills.Each calculator is also available as a Markdown "skill file" for Claude Code, ChatGPT, and other LLM workflows on our marketplace.
Branded embeds. Businesses can license a calculator with their colors and logo to drop into their own site.
Custom builds.If a calculation doesn't exist on the site yet, we build it to spec on a flat-fee basis.

None of these revenue streams influence editorial decisions about which calculators get published, how the math is implemented, or which third-party tools we recommend in articles.

Updates and the last-updated date

Each calculator page carries a "Last updated" date in the trust panel below the title. We update a page when any of the following changes:

A cited number changes — for example, the conventional conforming loan limit, the standard mileage rate, the federal student loan interest rate, or an IRS contribution cap.
A formula is refined or a worked example is corrected.
A reader-submitted correction is verified and published.
A new FAQ entry is added based on user questions.

We don't touch the "Last updated" date for cosmetic edits (typo fixes, layout adjustments) — only when the substance of the page changes.

Getting in touch

The fastest way to reach us is email: hello@calc.cards.

Corrections and accuracy reports— please include the calculator URL and the specific number or formula that looks wrong.
Request a calculator that doesn't exist yet — use the "Request" button in the header, or email us.
Press, partnerships, or licensing— same inbox.
Privacy and data requests — see the privacy policy for the formal process.

You can also reach the same team through the dedicated contact page.

A short note on the name

Calc.Cards is unrelated to two other things people sometimes search for with similar names: Oracle's "HCM Calculation Cards" payroll product, and the hydraulic-calculation cards used in fire sprinkler engineering. If you landed here looking for either of those, we unfortunately can't help with those specific products, and we apologize for the keyword overlap.