Fast tools for everyday math, money, health, and code.
CalcuSpec is a static, privacy-first utility hub covering calculators, converters, developer tools, and practical reference pages. Every tool gets its own clean page, instant results, and a clear explanation of the math behind it.
Tool categories
Fast, clean utility tools for everyday tasks: spec calculators, developer utilities, file tools, date helpers, and practical math.
Screen, print, video, storage, bitrate, and device-spec calculators.
75 tools ConvertersUnit, data, color, size, speed, pressure, and measurement converters.
1831 tools Developer ToolsJSON, CSV, encoding, hashes, timestamps, regex, SEO, and webmaster tools.
131 tools File & Image ToolsNo-upload browser tools for images, text files, QR codes, SVG, and PDF helpers.
27 tools Date & TimeDate math, business days, time zones, week numbers, deadlines, and planners.
37 tools Business & ShoppingPercentage, discount, price, margin, markup, invoice, and everyday calculators.
84 tools FinanceLoan, savings, interest, payoff, ROI, and investment calculators with clear disclaimers.
76 tools Health & FitnessWellness and fitness calculators that run locally and explain their formulas.
52 tools Home & DIYPaint, tile, flooring, concrete, garden, energy, and room calculators.
1267 tools Education & MathFractions, ratios, statistics, geometry, GPA, and student math helpers.
115 tools Travel & ReferenceCountry, currency, calling code, fuel, luggage, and public-holiday helpers.
37 tools Privacy & RandomPassword, passphrase, random picker, team, dice, and local privacy utilities.
34 toolsFocused tool collections
Curated tool hubs grouped for specific workflows, from screen and print specs to developer and no-upload file tools.
Fast calculators for PPI, aspect ratios, print size, video bitrate, file size, camera specs, audio timing, and storage planning.
75 tools No-Upload File And Image ToolsBrowser-based tools for image resizing, compression, checksums, QR codes, SVG conversion, text files, and PDF page checks.
27 tools Developer And SEO ToolsLocal developer utilities for JSON, CSV, Base64, URLs, regex, schema, robots.txt, sitemaps, Open Graph, HTTP, DNS, and CSS.
131 tools Unit Conversion ToolsCommon measurement converters for length, weight, area, volume, temperature, pressure, energy, power, data, speed, and time.
1831 tools Business And Marketing CalculatorsCalculators for percentages, discounts, margins, unit price, ads, email, SaaS metrics, customer acquisition, and operating ratios.
84 tools Finance Planning CalculatorsPlanning calculators for loans, mortgages, interest, payoff, savings, investment returns, rent, property tax, and inflation.
76 tools Date, Time, And Planning ToolsDate calculators for days between dates, business days, deadlines, time zones, pay periods, age, countdowns, and fiscal planning.
37 tools Home And DIY Project CalculatorsHome project calculators for paint, flooring, tile, concrete, mulch, roofing, drywall, lawn, solar, lighting, water, and airflow.
1267 toolsFeatured tools
The first set focuses on zero-cost, static-friendly tools that answer useful searches immediately.
Calculate your Body Mass Index (BMI) from height and weight, with WHO category classification.
Calculate what percent one number is of another, or find what value a percentage represents.
Guides
Plain-English explanations of the methods behind the calculators, with links to the relevant tools.
Why your first loan payment is mostly interest, how the split shifts over time, and how to use that to pay less interest overall.
BMI: what it measures, and what it missesBMI is a population-screening ratio, not a diagnosis. Here's what the number actually represents and where it tends to mislead.
A practical guide to subnetting and CIDRWhat a /24 actually means, how to find your usable host range fast, and the two host counts everyone forgets to subtract.