Free Converters Tools & Calculators
Browse 349+ free interactive converters calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
CCF to Therms Converter: Convert Natural Gas CCF to Therms
Free CCF to therms converter for natural gas bills. Convert CCF to therms (and back) with an adjustable conversion factor, estimate your gas bill, and convert to BTU, kWh, and MCF.
Celsius to Fahrenheit Converter: °C to °F Calculator with Table and Formula - nrtechstudio.com
Free Celsius to Fahrenheit converter with a two-way calculator, conversion formula, quick reference table from -40 to 100°C, and common temperatures like body temperature and oven settings.
Centigrade to Celsius Converter: Same Scale, History and Chart
Centigrade to Celsius calculator: centigrade and Celsius are the same scale, so conversion is instant. Includes the 1948 history, conversion formulas to Fahrenheit and Kelvin, and a full centigrade to Celsius conversion chart.
Centimeter Converter: cm to Inches, Feet, Meters and More
Free centimeters to inches calculator and cm converter hub. Convert cm to inches, feet, meters, millimeters, kilometers, yards, and miles instantly. Includes quick conversion tables, TV screen size cm to inches, and height cm to feet charts.
Cerebral Perfusion Pressure (CPP) Calculator — MAP − ICP | NR Tech Studio
Free cerebral perfusion pressure calculator: enter SBP, DBP and ICP to compute MAP and CPP (CPP = MAP − ICP), with BTF-based interpretation bands. Edu
UTF-8 Character Encoder & Text Sanitizer
Free online UTF-8 character encoder, Unicode inspector, and special characters remover. Convert unicode characters, remove special characters from string, and inspect byte encodings.
Chess ELO Calculator — FIDE, USCF, Chess.com & Lichess Rating Change, Performance Rating, Target Planner
Free chess ELO calculator and rating suite: single-game ELO change (FIDE K=40/20/10, USCF, Chess.com, Lichess), tournament simulator, reverse target planner, FIDE performance rating (Rp = Ra + dp), initial rating for unrated players, win-probability explorer and honest rating converter with uncertainty intervals. 100% client-side.
Child Cost Calculator — USDA Cost of Raising a Child to 18 | nrtechstudio.com
Child cost calculator: estimate the cost of raising a child to 18 with USDA data — by income, age, region and family size, plus inflation projection.
Clay Amount Calculator — How Much Clay Do I Need? (Mug, Bowl, Plate, Vase)
Free clay amount calculator for potters: how much clay do you need to throw a mug, bowl, plate, or vase? Batch mode for multiple pieces, wet vs dry weight converter, trimming waste allowance, and a class/workshop project planner. 100% client-side.
Cm to Km Conversion: Free Centimeters to Kilometers Calculator
Free cm to km conversion tool. Convert centimeters to kilometers and kilometers to centimeters instantly, with a full cm to km conversion chart, the formula, and answers to common questions. 100% client-side.
Cm to M Converter: Convert Centimeters to Meters Online
Free cm to m converter with two-way real-time conversion. Convert cm to meters and meters to cm, browse the cm to m chart, and get quick answers for common cm to m conversions.
Cm to Mm Conversion: Centimeters to Millimeters Calculator
Free cm to mm conversion calculator. Convert centimeters to millimeters and back instantly: 1 cm = 10 mm. Includes quick conversion table, formula, and worked examples for engineering, printing, and schoolwork.
CMYK Code & Universal Color Converter
Interactive CMYK color code converter, RGBA colour picker, RGB to HEX, HSV, HSL, decimal, and RAL color conversion tool.
Color Converter — HEX, RGB, HSL, HSV, CMYK, Lab + Palette & Contrast Checker
Free all-in-one color converter: convert between HEX, RGB, HSL, HSV, CMYK and Lab in both directions, generate palettes (complementary, analogous, triadic), check WCAG contrast, and pick colors from images. 100% client-side.
Colour RGB Values, RGBA Color Picker & Image Eyedropper
Free online colour RGB values inspector and RGBA color picker. Pick colours from images, convert hex code to rgba, rgba to rgb, generate randomized colors, and sample exact hexadecimal values.
Comma Delimited & List to String Converter
Interactive comma delimited formatter, list to string conversion tool, SQL quote wrapper, string to ASCII, and Python text to binary.
Commercial Lease Calculator — NNN vs Gross vs Modified Gross (Free)
Commercial lease calculator: compare gross vs NNN vs modified gross, build escalation schedules, amortize TI allowance, convert $/sqft — free, in-brow
Concrete Mix Calculator — Cement, Sand, Gravel & Water by Strength | nrtechstudio.com
Concrete mix calculator: cement, sand, gravel and water per m³ for 20–35 MPa mixes, with water–cement ratio guide, bag converter and yield check.
Contact Lens Vertex Distance Calculator — Convert Glasses Prescription to Contact Lens Power | nrtechstudio.com
Free contact lens vertex distance calculator. Convert your glasses prescription to contact lens power with the back vertex formula Fc = F / (1 − d·F). Includes a vertex conversion chart, nearest-0.25D rounding, and guidance for prescriptions over ±4.00D. 100% in-browser, no sign-up.
Convert pyproject.toml to setup.py Converter
Interactive Python packaging converter, migrating pyproject.toml to setup.py and setup.cfg with PEP 621 schema support.
JavaScript String to Array Converter
Interactive tool for converting a string to an array in JavaScript, splitting strings, and transforming JS objects into arrays.
Copper Wire Weight Calculator — Per Foot & Per Meter | nrtechstudio
Free copper wire weight calculator. Enter AWG gauge and length to get bare copper wire weight in lbs and kg — per foot, per meter, and per 1,000 ft — with a full AWG copper wire weight chart.
Crawl Ratio Calculator — 4x4 & Off-Road Gearing | nrtechstudio.com
Free crawl ratio calculator for 4x4 and off-road trucks. Multiply transmission, transfer case, and axle ratios to get your crawl ratio, gearing interpretation, and ground speed at idle RPM for any tire size.
Create Colour Palette from Image – Color Scheme Builder & Converter
Create colour palette from image, color hex code finder, color converter, 配色生成器, color scheme builder, ada color checker, brand color generator, make a color palette, pantone to hex converter, hex code finder from image, color chart for mixing colors, cmyk color tool, merge colors, hex color compare, dark theme color palette generator.
Crore to Lakh Converter - Indian Numbering System Calculator
Free crore to lakh converter: convert crore to lakh, lakh to crore, and to thousand, million and billion. Indian format (1,00,00,000) vs international (10,000,000) explained with examples.
Crore to Million Converter: Free Two-Way Crore to Million Calculator
Free two-way crore to million converter. 1 crore = 10 million exactly; 1 million = 0.1 crore. Also shows lakh, thousand, billion plus Indian (1,00,00,000) vs international (10,000,000) formats. Quick tables + funding and GDP context.
Speaker Crossover Calculator — 2-Way & 3-Way (Capacitor & Inductor Values) | nrtechstudio
Free speaker crossover calculator: enter crossover frequency, driver impedance and slope (6/12/18/24 dB/oct) to get exact capacitor (µF) and inductor (mH) values for 2-way and 3-way passive crossovers — Butterworth & Linkwitz-Riley, with nearest standard E12 parts. 100% client-side.
CSS Background Filter – Gradient Generator & CSS Shapes
CSS background filter, gradient background, gradient black css, background colour gradient, text gradient generator, gradient image maker, add gradient to image, gradient shadow css, gray gradient css, transparent gradient css, css shapes generator, box gradient css, css bg filter, webkit linear gradient, lineargradient html.
Cubic Feet to Gallons Converter (US and Imperial)
Convert cubic feet to gallons and back. 1 cubic foot = 7.48051948 US gallons or 6.22883546 imperial gallons. Free ft3 to gallon calculator with formula, quick table, and aquarium and pool examples.
Cubic Feet to Pounds Converter: Weight Calculator with Density Table
Free cubic feet to pounds calculator. Convert cubic feet to pounds using material density (water, concrete, soil, sand, gravel, steel) or a custom lb/ft3 value. Includes cubic feet to tons, a pounds per cubic foot chart, and the cubic foot to pounds formula.
Cubic Meter to Ton Converter | m3 to Tons Weight Calculator
Free cubic meter to ton calculator. Convert cubic meters (m3) to metric tons, kilograms, US tons and pounds using material density (water, concrete, sand, gravel, soil, steel) or a custom kg/m3 value. Includes a bulk density chart and a quick m3 to ton table.
Cubic Yards to Tons Calculator: Convert yd3 to US Tons, lb, kg and Tonnes
Free cubic yards to tons calculator. Convert yd3 to US tons, pounds, kilograms and metric tonnes for topsoil, gravel, sand, mulch, concrete and 20 materials, plus a quick tons-per-cubic-yard chart and dumpster weight guide.
Cups to Quarts Converter
Free cups to quarts converter with US liquid, imperial, and US dry modes. Convert cups to quarts or quarts to cups instantly, plus quick conversion charts and cooking measurement context.
Cv Flow Coefficient Calculator — Valve Sizing (Liquid & Gas)
Free Cv flow coefficient calculator for valve sizing: liquid Cv = Q×√(SG/ΔP), gas Cv with choked-flow detection, reverse solvers for flow rate and pressure drop, Cv to Kv converter, and typical valve Cv charts. 100% client-side, no signup.
D&D Name Generator & 5e Character Lore Maker
Interactive D&D name generator, human name generator DnD 5e, fantasy lore creator, and character background builder.
Data Rate Converter — Mbps, Gbps, MB/s, Bits vs Bytes (SI + IEC)
Free data rate converter: Mbps, Gbps, Kbps, bps to MB/s, GB/s and honest IEC Mibps units. Live two-way, download-time estimator, bits-vs-bytes guide. 100% client-side.
Data Storage Converter — Bytes, KB, MB, GB, TB, GiB
Free online data storage converter: convert bits, bytes, KB, MB, GB, TB, PB and binary KiB, MiB, GiB, TiB, PiB, plus a download transfer-time estimator. 100% client-side.
Days to Months Converter: Convert Days to Months Online
Free days to months calculator. Convert days to months with 3 methods: average month (30.44 days), exact calendar month, or simple 30-day month. Includes days to months chart, formula, and reverse months to days converter.
Days to Weeks Converter: Convert Days to Weeks Instantly
Free days to weeks calculator. Convert days to weeks with decimals, or see weeks and days breakdown. Also converts weeks back to days. Exact 1 week = 7 days.
Days to Years Converter: Convert Days to Years Instantly
Free days to years calculator with 3 year lengths: 365, 365.25, and 365.2422 days. Convert days to decimal years, see the years and days breakdown, and convert years back to days. Explains Google's 0.00273790926 answer.
dB Gain Calculator — Voltage, Power & dBm Converter | nrtechstudio.com
Free dB gain calculator: convert voltage gain to dB (20 log10), power gain to dB (10 log10), dB back to voltage and power ratios, dBm/dBW to watts, and add up cascade gains. 100% in-browser, no sign-up.
dBm to mW Converter: RF Power Conversion Calculator
Free dBm to mW calculator. Convert dBm to milliwatts, watts and dBW instantly with the formula P(mW) = 10^(dBm/10). Includes dBm to watts conversion table and WiFi signal strength guide.
dBm to Watts Converter: dBm, W, mW, dBW
Free dBm to watts calculator. Convert dBm to watts, milliwatts and dBW two ways, with the conversion formula, a dBm to watts table, and reference power levels.
Decimal to ASCII & Text Converter Online
Free online decimal to ASCII converter, decimal to text translator, and character to ASCII converter. Convert decimal to ASCII code and ASCII to decimal table.
Hex & RGB Color Converter with Pantone Matcher
High-precision decimal, RGB to hex converter, hex code to color name finder, and hexadecimal to Pantone color converter.
Decimal to Octal Converter | Free Online Base 8 Conversion Tool
Free decimal to octal converter: convert decimal to octal and octal to decimal instantly, with long-division steps, a 0-64 octal chart, and Unix chmod permission context.
Decimal to Ratio Calculator: Convert Decimals, Percents and Ratios
Free decimal to ratio calculator. Convert any decimal to a ratio in simplest form (0.75 becomes 3:4), turn ratios back into decimals, and convert percents to ratios. Includes a common conversion table, step-by-step working, and real-life uses in odds, aspect ratios, and recipes.
Decimal to Text Converter
Interactive decimal byte sequence to ASCII and UTF-8 plain text string decoder with automatic delimiter detection.
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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.