About All Calculator

Why We Started With One Calculator, Not Twenty

Most calculator sites launch with dozens of thin, half-finished pages covering every possible topic at once. We did the opposite. All Calculator opened with a single scientific calculator that actually worked well on a phone, loaded fast, and didn't hide basic features behind a sign-up wall. Only once that core experience was solid did we start building out dedicated calculators for specific tasks, and each one follows the same rule the first one did: it has to actually be useful on its own, not just exist to pad out a list.

What All Calculator Offers Today

The site currently includes 11 calculators across four categories: Numbers & Fractions (percentage, fraction, decimal to fraction, square root, prime factorization), Health & Body (BMI, calorie, age), Computer Science (binary), and Physics (velocity). Every calculator includes a full written guide alongside the tool itself, covering the formulas, common mistakes, and real situations where that calculation actually comes up, not just a bare input box and an answer.

How We Build Each Calculator

Before a new calculator goes live, we look at what similar tools elsewhere already do well, then find something genuinely missing rather than copying the same feature set. Our Fraction Calculator, for example, includes a recipe-scaling mode most competitors don't offer. Our BMI Calculator surfaces specific, personalized context notes (for athletes, pregnancy, age, and ethnicity factors) instead of one generic disclaimer nobody reads. That's the standard we hold every new calculator to: it should do something a visitor can't easily get from the first three results on Google.

How This Is Different From When We Started

The original version of this site was one calculator page. As we've built out dedicated tools for specific tasks, each new calculator has been paired with its own guide rather than bolted onto the general one. That's a deliberate choice: a percentage calculator built specifically for percentages can go deeper on that one topic than a single tool trying to cover everything at once.

Who Uses All Calculator

Students use it to check homework answers and see the working, not just the final number. Shoppers use it to verify discounts and compare prices. Small business owners use it to check markup, margin, and sales tax on pricing decisions. Anyone tracking their weight, age, or daily calorie needs uses the health calculators, alongside the honest limitations we include with them rather than treating a single number as a verdict.

Accuracy Matters to Us

Every formula on this site is checked against standard references before it's published, and every calculator shows its working, not just a final number, so anyone can verify the method themselves rather than taking the result on faith. If you ever spot a calculation that looks wrong, we want to know, and we treat that kind of feedback as a priority, not a nuisance.

Our Commitment

Every calculator on this site is free, with no subscription, no paywall, and no login required, and that isn't going to change. We're continuing to add new calculators on a regular basis, organized into the same category structure so related tools stay easy to find and link to each other. If there's a calculation you use regularly that we don't yet offer, tell us, we read every message and use that feedback to decide what to build next.