400+ calculators · formulas explained

Free online calculators with formulas and worked examples.

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Every collection is organized around a clear task, with direct access to its calculators.

FinancialLoans, mortgages, savings and tax estimates 102 tools MathPercentages, algebra, geometry and statistics 45 tools HealthBMI, nutrition, fitness and wellness estimates 40 tools Date & TimeAge, duration, workdays and time zones 19 tools ConvertersUnits, currency, measurements and data 22 tools BusinessPricing, payroll, margins and growth 51 tools EducationGrades, GPA, study planning and scores 16 tools ConstructionConcrete, roofing, materials and layouts 19 tools EngineeringElectrical, HVAC and mechanical calculations 24 tools LifestyleTravel, cooking, household and daily planning 31 tools Document ToolsPDF, image and everyday document utilities 24 tools Developer ToolsGenerators, encoders and web utilities 24 tools NetworkingSubnets, bandwidth, IP and transfer tools 8 tools PhysicsMotion, energy, force and waves 16 tools

From the Numeros blog

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Privacy by designMost calculations run locally in your browser.
Many tools work offlineMany standard tools remain usable without a connection.
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Before you start

Common questions

What the numbers mean, where they come from, and what happens to what you type.

Do you store the numbers I enter?

Most calculations run locally in your browser. Some tools save drafts, preferences or optional API keys on your device. Tools that use external services may send the information needed for a lookup or request, such as QR text, search terms, domains or location coordinates after your permission. Read the tool-specific notice and our privacy policy before entering sensitive information.

Do I need an account to use anything?

You do not need a Numeros account to use the site. Some tools rely on external providers that may require their own API key or apply usage limits. Tools with live data may need to finish loading that data before producing a result.

How do the calculators work offline?

Many calculators continue working after their page and required resources have loaded because the calculation runs on your device. Live prices, rule updates, public lookups and connection tests need internet access. Offline use does not guarantee that live data is current or that every tool remains available.

Why do you show the formula?

So you can check the answer instead of trusting it. Every tool shows the working with your own figures substituted, plus a worked example. If a result looks wrong, you can see exactly which step produced it — which also means you learn something, rather than just collecting a number.