Free Converters Tools & Calculators
Browse 349+ free interactive converters calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
Hardness Conversion Calculator: Brinell, Vickers, Knoop, Shore and Mohs
Convert hardness between Brinell (HB), Vickers (HV), Knoop (HK), Shore A/D, and Mohs with an approximate conversion calculator, Brinell/Vickers/Knoop test calculators, a chart, and inline reference tables. Free, client-side.
Heat Transfer Coefficient Calculator — U-Value, R-Value & Unit Converter | nrtechstudio.com
Free heat transfer coefficient calculator: convert W/m²·K to BTU/(hr·ft²·°F) and kcal/(h·m²·°C), compute multi-layer wall U-value & R-value per ISO 6946, and heat loss Q = U·A·ΔT. 100% in-browser, no sign-up.
Hexadecimal Translator & Hex Text Converter
High-performance bidirectional hexadecimal translator and hex code decoder. Convert text to hexadecimal and decode hex to text with UTF-8 and ASCII support.
Hex To Morse
Convert Hexadecimal to Morse Code.
Hex to RGB Converter: HEX RGB RGBA HSL + Palette Generator
Free two-way hex to rgb color converter: HEX to RGB, RGB to HEX, hex to rgba, hex to hsl. With color picker, complementary/analogous/triadic palette, shades/tints, WCAG contrast checker, and a table of 20 popular web colors. 100% client-side.
Horse Gestation Calculator — Mare Due Date, Countdown & Foaling Timeline
Free horse gestation calculator: enter a breeding date to get the foaling due date (340-day average, honest 320-360 day window), live countdown, milestone timeline, reverse breeding planner, multi-mare batch planner, foaling signs and printable foaling kit checklists. Runs 100% in your browser.
Hour Converter: Hours to Minutes, Seconds, Days, Weeks
Free hour converter: convert hours to minutes, seconds, days, weeks, months, and years instantly. Plus decimal hours to HH:MM:SS and a quick hourly-to-pay calculator. 100% client-side, works offline.
HP to Amps Calculator — Horsepower to Amperage (DC, Single-Phase & 3-Phase)
Free HP to amps calculator: convert motor horsepower to full-load amps for DC, single-phase and three-phase motors with efficiency & power factor. Reverse amps-to-HP mode, NEC FLA table, breaker & wire size hints. 100% client-side.
HP to kW Converter - Horsepower to Kilowatts
Free HP to kW converter: convert mechanical horsepower to kilowatts, metric PS, watts and back. Exact definitions (1 hp = 0.745699872 kW, 1 PS = 0.73549875 kW), quick tables, EV, engine and AC examples.
Universal HTML Converter & Cleaner
Interactive HTML converter suite to convert HTML to Excel, HTML to Word, text to HTML, link to HTML, and clean HTML code online.
HTML Entity Encoder & Decoder
Standalone professional HTML entity encode and decode developer tool. Encode special characters to HTML entities or decode HTML string back to raw text. Supports named, decimal, and hexadecimal entities.
Html Table To Csv
Extract HTML <table> elements into CSV.
Hyperlink in WhatsApp Web & Message Link Generator
Interactive tool to create WhatsApp message links, click-to-chat hyperlinks for WhatsApp Web, and pre-filled message URLs.
Hz, kHz, MHz, GHz Frequency Converter
Interactive frequency converter across Hertz, Kilohertz, Megahertz, and Gigahertz with RF spectrum band diagnostics.
iCal Parser
High-performance interactive iCalendar (.ics) Parser, RFC 5545 calendar validator, and JSON converter with 100% SEMrush keyword optimization.
Image to Base64 Converter
Free online image to Base64 converter. Upload any image and instantly get its Base64 encoded string, Data URI, and CSS background-image code. Supports PNG, JPG, GIF, WebP, SVG.
Image to Black & White Converter — Free, 100% in Browser
Turn photos black-and-white free right in your browser: BT.709/BT.601 grayscale, 1-bit threshold, Floyd–Steinberg & Bayer dithering, Photocopy/Newspaper/Stamp/Sketch presets, batch ZIP. No upload — images never leave your device.
Imperial to Metric Conversion Calculator - Free Online Converter
Free imperial to metric conversion calculator: inches to cm, feet to meters, miles to km, pounds to kg, ounces to grams, Fahrenheit to Celsius, gallons to liters (US vs imperial). Exact factors, 100% client-side.
Inch Lbs to Nm Converter: In·lb to N·m Torque Conversion
Free inch lbs to Nm converter. Convert in·lb to N·m and back, plus ft·lb, kgf·m and ozf·in. Exact factor 0.11298482903, torque table, bolt specs, and torque-wrench context. Works offline.
Inch-Pounds to Foot-Pounds Converter (in·lb to ft·lb) - Free Torque Tool
Free inch-pounds to foot-pounds converter: convert torque both ways (1 ft·lb = 12 in·lb) with newton-metre output, a quick reference table, and torque-wrench range guide. 100% client-side.
Inch to Meter Converter: in to m Calculator with Formula
Free inch to meter converter and meter to inch converter. Convert inches to meters (multiply by 0.0254) or meters to inches (divide by 0.0254) with live results, feet-and-inches helper, quick conversion table, 20 popular conversions, and FAQ.
Inches to Yards Converter: In to Yd Calculator
Free inches to yards converter and yards to inches calculator. 1 yard = 36 inches exact. Includes quick tables, formula, fabric, football and construction contexts.
Inflation Calculator — What Is Your Money Worth Over Time? (1913–2026, 6 Countries)
Free inflation calculator: convert money between any two years (1913–2026) for the US, UK, Euro area, Canada, Australia and Indonesia using official CPI data. See equivalent value, total & annual inflation, purchasing-power chart and year-by-year table.
Integer to Roman Numerals Converter — Convert Numbers to Roman Numerals (Free)
Convert integers to Roman numerals free: 1–3999 standard plus vinculum overline notation to 3,999,999. Batch mode, reference table, 100% private.
Inverting Buck-Boost Converter Calculator — Duty Cycle, Inductor & Output Ripple | nrtechstudio.com
Free inverting buck-boost converter calculator: duty cycle, inductor ripple current, output ripple voltage, CCM/DCM boundary (L_min), peak-current inductor rating and L/C component selection for negative-rail DC-DC designs.
IQ Percentile Calculator — IQ to Percentile, Percentile to IQ, Classification Table
Free IQ percentile calculator: convert IQ score to percentile (Wechsler SD 15, Stanford-Binet SD 16, Cattell SD 24), percentile back to IQ, z-score, r
Isentropic Flow Calculator — Mach Number, Pressure, Temperature & Area Ratios | nrtechstudio.com
Free isentropic flow calculator: enter Mach number to get T0/T, p0/p, density ratio, A/A* area ratio, Mach angle and Prandtl-Meyer angle — or solve the inverse (Mach from A/A*, T0/T, p0/p) with subsonic/supersonic branches. Interactive isentropic flow table, choked-flow guide. 100% in-browser, no sign-up.
Joules to Kilojoules Converter (J to kJ)
Free joules to kilojoules converter. Convert J to kJ and kJ to J instantly, plus the full energy unit ladder (MJ, cal, kcal, Wh, eV), formulas, quick tables and FAQs.
JS Char Code Generator
High-performance bidirectional JavaScript CharCode converter, charCodeAt and String.fromCharCode online tool with UTF-16/UTF-32 and ASCII table analysis.
JSON Object Structure & CSV to JSON Formatter
Free online JSON object structure visualizer and CSV to JSON formatter. Convert CSV to JSON format, table to csv, create JSON objects, inspect JSON coding schemas, and export Java JSONObject to string.
JSON Object Viewer – Interactive Tree & JSONPath Editor
Json parse json, json object viewer, jsonpath online editor, javascript json reader, create json, what is the json format, json stringify js, convert object to array in javascript, parse string javascript, json file reader online, convert js object to array, sql json extract, parse json in node js, json tryparse javascript, javascript define json object.
JSON Online Editor, Schema Generator & JSON-LD Validator
Interactive JSON online editor, JSON Schema creator, structured data markup generator (Product, Article, LocalBusiness), and JSON-to-XML converter.
Json To Csv
Convert JSON arrays to CSV format.
Json To Excel
Json To Go Struct
Json To Java Pojo
JSON to JS Object & String Converter
Free online JSON to JS object converter, JSON string to JSON object parser, and JavaScript object to JSON converter. Convert JSON to JSON string and JS object to JSON.
JSON to SQL Converter
Convert JSON arrays and objects into MySQL, PostgreSQL, SQLite, and SQL Server INSERT statements and DDL schemas.
Json To Table
Json To Yaml
JSON Web Signature Decode – JWS, Base64 & Multi Decoder
JSON web signature decode, base 64 converter, encodebase64 javascript, base 64 to text, b64encode online, hexadecimal reader online, converting between base 64 and base 64 url, urldecode in javascript, base64 online, how to decipher binary, base 62 encode, bash decode base64, base64 chars, convert image to base 64, bytes to text, mac decode base64, openssl base64 decode, decodebase64 java.
Julian Date Converter — JDN, Julian Calendar & Ordinal Date (Free Online)
Free Julian date converter: Julian Day Number (astronomy), Julian calendar ↔ Gregorian, and ordinal dates (yyddd, yyyyddd, JDE Cyyddd) — plus MJD and heliocentric JD. Verified math, 100% client-side.
Katha to Square Feet Converter - Regional Katha Calculator
Free katha to square feet converter with verified regional values: Bihar 1361 sq ft, West Bengal 720 sq ft, Assam 2880 sq ft, Bangladesh 720 sq ft. Convert katha to sq ft, sq m, acres, hectares, bigha.
Kelvin to Celsius Converter (K to °C) - NR Tech Studio
Free Kelvin to Celsius converter with live two-way K to °C and °C to K conversion, adjustable precision, step-by-step working, landmark table and FAQs.
Kelvin to Fahrenheit Converter: K to °F Calculator with Formula, Table and Steps - nrtechstudio.com
Free Kelvin to Fahrenheit converter with live two-way K to °F calculation, the exact formula, step-by-step worked examples, a conversion table, and reference points like absolute zero, freezing and boiling water.
kg/cm2 to psi Converter: kgf/cm2 to psi, Both Directions
Free live converter: kg/cm2 (kgf/cm2) to psi and psi to kg/cm2, both directions. Exact factor 14.223343307, swap, precision control, worked derivation, conversion chart 0.5-20 kg/cm2, and 14 answered FAQs.
Kg to Gallons Converter | Kilograms to Gallons Mass Volume Calculator
Convert kilograms to gallons with density. Free kg to gallons calculator: water, milk, diesel, gasoline, oil, honey and custom density. US and imperial gallons, live 2-way conversion.
Kg to mL Converter: Kilograms to Milliliters with Density
Convert kilograms to milliliters and milliliters to kilograms using density. 8 substance presets (water, milk, oil, honey, flour, sugar, salt, butter) plus custom density, live two-way conversion, formula shown.
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How to Use the Tools Directory
Every tool is a single interactive page: enter your inputs, get instant results, no account needed. Use the search box (shortcut: press /) to jump straight to a tool, or browse categories when you are exploring. Each card links to the tool's permanent URL, which you can bookmark or share.
Because all computation happens in your browser, the tools are fast, private, and free forever. If a result looks wrong, use the one-click report control on the tool page so it can be fixed.
Tool Categories at a Glance
| Category | What you will find | Example tasks |
|---|---|---|
| Developer | Encoders, formatters, regex, network tools | Format JSON, test regex, subnet a network |
| Finance | Tax, loans, salary, investing | Estimate tax brackets, amortize a loan |
| Home improvement | Estimators, measurements, materials | Size a wire, estimate paint or flooring |
| Health & fitness | Body metrics, nutrition, workouts | Track BMI, plan calories, score fitness tests |
| Math & science | Converters, geometry, statistics | Convert units, solve triangles |
| Text | Counters, sorters, generators | Count words, alphabetize a list |
| Color | Pickers, converters, checkers | Convert HEX to RGB, check contrast |
| Everyday life | Cooking, travel, automotive, pets | Convert recipes, plan fuel costs |
Popular Tasks and Where to Start
| I want to... | Start with | Why |
|---|---|---|
| Convert between number bases | Binary Converter | Step-by-step base conversion with charts |
| Validate and format data | JSON Formatter | Pretty-print and check JSON instantly |
| Count words for an essay | Word Counter | Words, characters, reading time |
| Check password strength | Password Strength Meter | Entropy-based strength scoring |
| Grade text readability | Readability Score | Flesch-Kincaid and grade levels |
| Audit color contrast | Accessibility Checker | WCAG contrast ratios in one click |
Tools Directory FAQ
What is the NRTechStudio tools directory?
It is a free catalog of more than 2,700 interactive web tools: calculators, converters, generators, and checkers for developers, finance, home improvement, health, education, and everyday tasks.
Are all the tools really free?
Yes. Every tool in the directory is free to use with no sign-up, no trial, and no paywall. They run entirely in your browser.
Do I need to create an account?
No. There are no accounts, logins, or subscriptions. Open a tool and use it immediately.
Is my data private when I use these tools?
Yes. The tools are 100% client-side: your inputs are processed by JavaScript in your own browser and never sent to a server.
How do I find the right tool?
Use the search box at the top of the directory (press / to focus it), or browse by category. Every tool card shows a short description of what it computes.
Do the tools work on mobile?
Yes. The directory and the tools use responsive layouts that adapt to phones, tablets, and desktops.
How many tools are there?
The directory holds more than 2,700 tools and grows regularly as new calculators and converters are published.
Can I request a new tool?
Yes. Each tool page has a report/feedback control you can use to request features or new tools; requests help prioritize what gets built next.
Are the tools accurate?
Calculators use published formulas and reference data (tax tables, NEC ampacity, standard conversions). Each tool page documents its method, and issues can be reported in one click for a fix.
Do tools work offline?
Once a tool page has loaded, most tools keep working without a connection because the logic is client-side JavaScript. The directory search needs the page loaded first.
What categories are covered?
Developer utilities, finance and tax, home improvement, health and fitness, math and science, text tools, color tools, networking, education, and everyday life calculators, among others.
Can I bookmark or share a tool?
Yes. Every tool has its own permanent URL under nrtechstudio.com/tools/, which you can bookmark or share directly.
Is there an API for these tools?
The tools are interactive web pages, not API endpoints. The underlying math is plain JavaScript you can inspect in the page source.
Why do some tools show ratings?
Ratings aggregate user feedback to surface the most trusted tools and flag pages that need fixes or better explanations.
How often are new tools added?
New tools are published on a continuous pipeline, prioritized by measured search demand and by user requests from the feedback controls.
Who builds these tools?
NRTechStudio, an independent tools studio focused on free, private, client-side utilities that respect user privacy.