Free Online Calculators
Free Online Calculators You Can Actually Check
Calculator Archive is a free, open-access collection of more than 90 online calculators covering finance, health, mathematics, and everyday problem solving. There is nothing to install, no account to create, and no personal data to hand over — you choose a tool, enter your values, and the result appears instantly in your browser. Every calculation happens locally, so the numbers you type are never sent to a server.
A result you cannot trace is not much use, so each calculator states the formula it applies and the assumptions it makes. Mortgage and loan tools disclose their amortisation method and compounding frequency. Health calculators name the equation they use — Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle — and show where their activity factors come from. Statistical tools display the sample formula rather than only the answer. Where an official source sets the figures, such as tax brackets or contribution limits, the calculator is revised when that source changes.
Browse by Category
Four directories group the tools that belong together, each with a short note on what it is best at, so you land on the right calculator rather than the first one you find.
Mortgage payments and amortisation schedules, loan and auto financing, refinancing, tax and take-home pay, retirement and pension projections, investment returns, savings goals, and currency conversion. The largest directory on the site.
BMI, body fat percentage, basal metabolic rate, daily calorie and macronutrient targets, ideal weight, running and walking pace, target heart rate zones, water intake, pregnancy dating, and due dates.
Scientific and basic arithmetic, fractions, percentages, exponents and roots, triangles and geometry, factors and factorials, binary and number bases, random number generation, and standard deviation with variance.
Age and date differences, hours worked, grades and GPA, unit and data conversions, IP subnet masks, password generation, and construction material estimates for concrete and aggregates.
How Every Result Is Checked
Published formulas
Each tool names the standard it follows — amortisation tables, WHO biometric references, IEEE-754 arithmetic — rather than an unexplained number.
Nothing is collected
Calculations run in your browser. We do not require registration and do not ask for income, health, or identity details to produce a result.
Kept current
Tools that depend on official rates, brackets, or limits are reviewed when those sources publish new values, and the change is applied to every affected calculator.
Corrections welcome
Found something that looks wrong? Report it through the contact page with your inputs and we will verify it against the source formula.
Frequently Asked Questions
Is Calculator Archive really free?
Yes. Every calculator is free to use without registration, a subscription, or an email address. The site is supported by advertising, which is why you may see advertisements alongside the tools.
Do you store the numbers I enter?
No. Calculations run entirely in your browser with standard JavaScript arithmetic. The values you type are not transmitted to our servers, and no account or profile is created for you.
How accurate are the results?
Calculators use double-precision floating-point arithmetic and formulas taken from published sources. Where rounding matters — currency, tax, or engineering outputs — the page states how the result is rounded. If you spot a discrepancy, report it with your inputs and we will check it.
Can I use these calculators for professional or financial decisions?
They are intended for estimation and education. For a binding financial, medical, tax, or engineering decision, confirm the figure with a qualified professional and the relevant official source.
How do I request a calculator that is missing?
Send the calculation you need, along with a formula or worked example if you have one, through the contact page. Requests are prioritised by how many readers ask for the same tool.