Free Converters Tools & Calculators
Browse 349+ free interactive converters calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
3kg to Lbs Converter
High-precision 3kg to Lbs Converter, Kilograms to Pounds & Ounces, Weight Converter Unit Table.
Accent Chair Size Calculator — 7 Ways to Find Your Perfect Chair
What size accent chair do you need? Free 7-mode calculator: seat height, depth, width, sofa match, room fit, walkway clearance and size class. Inches
Acreage Calculator — Land Area in Acres, Hectares & Sq Ft
Free acreage calculator: compute land area in acres from length × width, triangle, trapezoid, circle, or irregular 4-sided lots. Results in acres, hectares, sq ft, sq m, and perimeter.
Acres Per Hour Calculator — Field Work Rate (Spraying, Mowing, Tilling) | nrtechstudio.com
Free acres per hour calculator: enter implement width, speed and field efficiency to get acres/hour and hectares/hour, with reverse solver, time planner, typical speed tables and worked examples. 100% client-side.
Acres to Hectares Converter — Free Two-Way acres ↔ hectares Tool
Free acres to hectares converter with exact constants (1 acre = 0.40468564224 ha). Convert acres ↔ hectares plus sq ft, sq m, sq km, quick conversion table and the formula.
Add Text to Each Line Online – Text Line Tools
Online text tool to add prefix/suffix to each line, whatsapp conversation generator, and AI tools examples reference.
Ah to kWh Calculator — Convert Battery Amp-Hours to Kilowatt-Hours
Free Ah to kWh calculator: convert battery amp-hours to kilowatt-hours (kWh = Ah × V ÷ 1000). Also converts kWh back to Ah, handles mAh, battery presets, series/parallel banks, and estimates device runtime.
Air Compressor Size Calculator — CFM, Tank, HP & Breaker Sizer | nrtechstudio.com
Size your air compressor right: match CFM to air tools, pick tank gallons, single vs two-stage, plus breaker and wire size. Free, 100% in-browser tool.
Amps to kW Calculator — DC, Single-Phase & 3-Phase Converter
Free amps to kW calculator: convert amps to kilowatts for DC, single-phase and three-phase (line-to-line / line-to-neutral) with power factor. Also kW to amps, amps to watts, amps to kVA, and a breaker-size chart. 100% client-side.
Amps to Ohms Calculator — Convert Amps to Resistance (DC, AC, 3-Phase)
Free amps to ohms calculator: convert amps to resistance for DC, AC single-phase and 3-phase circuits, reverse ohms to amps, Ohm
Angle Converter - Degrees, Radians, Gradians, Turns & More
Free angle converter: convert degrees, radians, gradians, turns, arcminutes, arcseconds and milliradians live, with exact pi fractions, batch mode and DMS readout.
Antenna Lab: Dipole, J-Pole, Mag Loop & Yagi Calculator
Free wire antenna design suite: dipole & inverted-V calculator (468/f), quarter-wave vertical + radial planner, random wire & end-fed half-wave (EFHW), J-pole & Super J-pole, magnetic loop tuning capacitor calculator, multi-element Yagi designer, length converter and wire gauge reference. Metric + imperial. 100% client-side.
Aquarium Salinity Converter — ppt ↔ Specific Gravity ↔ mS/cm (Free)
Free aquarium salinity converter: convert ppt ↔ specific gravity ↔ conductivity (mS/cm) ↔ density with full temperature compensation (UNESCO equation). Hydrometer temperature correction, salt-mix dosing calculator, livestock targets & hyposalinity planner. 100% client-side.
Archery Draw Length Calculator — Wingspan, Arrows & Bow Fit
Free archery draw length calculator: enter your wingspan to get AMO draw length, arrow length, bow size fit, and draw-weight guidance. 100% client-side.
Ares to Cents Converter — Free ares ↔ cents Area Converter (India)
Free two-way ares to cents converter. 1 are = 2.4710538147 cents; 1 cent = 0.40468564224 ares. Also shows m², sq ft, acres & hectares. Quick tables + India land-unit context.
ASCII Code Translator & Binary Chart
Interactive ASCII code translate tool, binary to number table, hex to binary chart, and alphabet character encoding converter.
ASCII to Decimal Converter
Interactive ASCII character to decimal byte sequence converter with custom delimiters, radix tables, and live analysis.
AWG to mm Converter — AWG to mm² Wire Size Calculator | nrtechstudio
Convert AWG to mm, mm², inches and circular mils (0000–40), reverse-convert mm/mm² to AWG, browse the full NEC ampacity table, and size wire with a 3% voltage-drop advisor. 100% client-side.
Baby Eye Color Calculator & Predictor — What Color Eyes Will My Baby Have?
Free baby eye color calculator: pick both parents' eye colors (optionally the grandparents') to estimate your baby's odds of brown, hazel, green, or b
CSS Liquid Gradient & Background Generator
Interactive background generator CSS with animated CSS liquid gradient, mesh blurs, and developer-grade CSS generators.
Bar to PSI Conversion — Free Bar ↔ PSI Converter (kPa, MPa, atm)
Free bar to psi converter with psi to bar reverse conversion. Exact factor 1 bar = 14.5038 psi. Convert bar, psi, kPa, MPa, kgf/cm² and atm instantly, with a quick table and tire pressure presets.
Number Base Converter (Base 2–36) with Place-Value Visualizer | nrtechstudio.com
Free number base converter: convert between any bases 2–36 (binary, octal, decimal, hex and beyond). See every digit
Base16 Decoder & Hex Encoder
RFC 4648 Section 8 Base16 hexadecimal encoder, decoder, and UTF-8 string conversion online tool.
Base64 Character Set & Live Encoder
Interactive Base64 character set visual table (indices 0-63), RFC 4648 standard vs URL-safe mapping, bitwise binary breakdown, and live encoder/decoder.
Base64 Encoder / Decoder
Engineering-grade Base64 Encoder and Decoder with UTF-8 support, image & PDF decoding, file preview, and CLI commands.
Base64 Translator – URL, JSON & Developer Codec Suite
Base64 translator, json array data, urlencode in js, js uri encode, json dictionary, decode urlencoded, javascript encode url, python url decode, javascript uri encode, json deserialize, convert string to json python, javascript decode url, python convert string to json object, urlencode javascript, html decode online, unicode to char converter, javascript create a json object, python encode utf 8, js encode, url special characters, decrypt hexadecimal code, decode html url, decode sha 256, encode string js, convert url to link, utf16 encoder, json to one liner, javascript encoding string, character code js, json url encode.
Base64 URL Encoder & Decoder
RFC 4648 URL-safe Base64 encoder and decoder online tool with live character replacement and JWT payload inspector.
Base85 / Ascii85 Decoder
Enterprise-grade interactive Base85 and Ascii85 decoder, multi-variant encoder, and byte stream analyzer with 100% SEMrush keyword optimization.
Beer ABV Calculator — OG/FG, Refractometer Correction, Hydrometer Temp Correction (Free)
Free beer ABV calculator lab: standard, alternate & real-extract formulas side-by-side, refractometer alcohol correction (Terrill), hydrometer temperature correction, attenuation, dilution, Brix/Plato/SG converter. 100% client-side.
Bike Frame Size Calculator — 7 Sizing Modes
Free 7-mode bike frame size calculator: road, MTB, hybrid and gravel sizing from inseam, LeMond saddle height, reach and stack, standover check, kids bike sizer, size converter.
Billion to Trillion Converter — Free Online Tool
Convert billions to trillions and trillions to billions instantly. Free 2-way converter with million and quadrillion support, quick tables, and short vs long scale explained.
Binary Converter
Convert text to binary and decode binary to text.
Binary Decoder – Binary to English, ASCII Code Generator
Binary decoder, binary to English, ASCII code generator, words to binary, binary numbers base 10, convert bytes, binary code encoder, image to binary converter, symbols to binary.
Binary To Text
Convert binary code back to ASCII text.
Bond Price Calculator: YTM, Current Yield, BEY, Duration & Convexity
Complete bond calculator: compute bond price, YTM (yield to maturity), current yield, BEY (bond equivalent yield), Macaulay & modified duration, and convexity — with cash flow tables and price vs yield sensitivity.
Book Signature Calculator — Imposition Maps, Planner & Binding Lab | nrtechstudio
Free bookbinding signature calculator lab: signature planner (pages per signature), folio/quarto/octavo imposition page-order maps, format size converter, paper grain advisor, sewn-vs-perfect binding decision helper, and thread & material estimator. 100% client-side.
Braille Translator — Text to Braille & Back
Free online Braille translator: convert text to Braille (Unicode) and Braille back to text. Grade 1 alphabet, number and punctuation chart, per-character dot mapping, copy and download. 100% client-side.
BTU to Tons of Refrigeration Converter — Free HVAC Capacity Calculator | nrtechstudio
Free BTU to tons converter: convert BTU/hr to tons of refrigeration and back (1 ton = 12,000 BTU/hr). Plus kW/watts equivalents, AC size chart, and room sizing rule of thumb. 100% client-side.
Buck Converter Calculator — Step-Down DC-DC Design | nrtechstudio.com
Free buck converter calculator: compute duty cycle, inductor value, output capacitor, ripple current and voltage for step-down DC-DC designs. Continuous vs discontinuous mode indicator and component selection guidance included.
C String Unescaper
High-performance developer tool to unescape string literals and decode escaped C strings, hex, octal, and Unicode sequences online.
Cabin Size Calculator — 7 Ways to Size Your Cabin
How big should your cabin be? Free 7-mode cabin size calculator: occupants, bedroom, kitchen, bath, deck, loft and off-grid utility sizing — sq ft + s
Cake Pan Conversion Calculator — Pan Size, Batter & Bake Time Converter
Convert cake recipes between pan sizes with batter-depth checks and bake adjustments.
Candela to Lux Converter — Inverse-Square Law Calculator | nrtechstudio
Free candela to lux converter with the inverse-square law: convert candela ↔ lux at any distance, candela ↔ lumens via beam angle, and lux ↔ lumens via area. Worked examples, formulas, and honest limitations. 100% client-side.
Candle Fragrance Load Calculator & Wax Suite — Fragrance Oil, Wax Amount, Batch Planner
Free candle fragrance & wax calculator suite: fragrance load calculator (% of wax vs % of finished batch), wax amount from container volume, wax-type database (soy, paraffin, beeswax, coconut max loads), batch scaler, reverse planner, g↔ml converter, wax melt lab, and melt/pour/cure reference tables. Metric + imperial. 100% client-side.
Capacitor Energy Storage Calculator — E = 1/2 CV^2 (Joules, Wh, Charge) | nrtechstudio.com
Free capacitor energy calculator: enter capacitance & voltage to get the energy stored in joules and watt-hours plus the charge in coulombs. Reverse solvers find C or V from a target energy, with a battery comparison and high-voltage safety notes. 100% client-side, no sign-up.
Catculator: Cat Age Calculator — Cat Years to Human Years
Free Catculator: convert cat years to human years (and back) with month-level precision. Year 1 = 15, year 2 = 24, then +4/year. Life stages, interactive age chart, birthday countdown. 100% client-side.
CC to Grams Converter: Volume to Mass Calculator with Density Table
Free online cc to grams converter and grams to cc converter. Enter a volume in cc, pick a substance density (water, flour, sugar, oil, honey, milk) or enter custom g/cc. Formula, conversion chart, and FAQ included.
cc to ml Converter: 1 cc = 1 ml Exact Conversion with Syringe Dosing Guide
Free cc to ml converter. 1 cc = 1 ml exactly. Convert cc to ml, ml to cc, liters, teaspoons, tablespoons, fluid ounces and cups, with syringe dosing examples and medical FAQs.
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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.