Free Online Tools for Everything You Do
Browse 2,706+ free interactive tools - home improvement estimators, pet calculators, cooking converters, automotive tools, finance planners, fitness calculators, developer utilities and more. No sign-up. 100% private. Runs entirely in your browser.
Margin & VAT Calculator — True Margin from Tax-Inclusive Price
Free margin with VAT calculator: compute the true margin from an inc-VAT price, extract the tax first, compare ex-VAT vs inc-VAT, and a selling-price solver from a target margin.
Profit Margin Calculator: Net, Operating & EBITDA Margin | NR Tech Studio
Free profit margin calculator: net, operating, EBITDA margin, markup to margin converter, commission impact, break-even units and reference tables.
Stock Margin Call Calculator: Status, Trigger Price & Solver
Compute stock broker margin calls: account status, shortfall amount, the stock price that triggers a margin call, a 2-scenario comparator, and a deposit or sell solver. Educational estimate, not investment advice.
Discount Impact on Margin Calculator — Free
Compute the impact of discounts on profit margin: margin after discount, maximum discount to hit a target margin, a two-level discount comparator, and a list-price solver. Free, 100% in the browser.
Stock Broker Margin Interest Calculator — Margin Loan Cost
Free margin interest calculator: compute stock broker margin loan interest cost (balance × rate × days/360), a 2-broker comparator, monthly & yearly cost projection, and a maximum loan solver.
Marginal Cost Calculator — MC = ΔTC/ΔQ + Table & Solver
Marginal cost calculator: compute MC = ΔTC/ΔQ from two cost points, multi-point table analysis, compare MC vs ATC/AVC, + TC2 & Q2 solver. 100% in the browser.
Marginal Revenue Calculator — MR = ΔTR/ΔQ + Table & Solver
Marginal revenue (MR) calculator: compute MR = ΔTR/ΔQ from two points, multi-point table, MR vs MC comparator, + TR2 & Q2 solver. 100% in the browser.
Markdown Formatter, Editor & Converter
Free web markdown editor, formatter, and visualizer. Convert markdown to HTML online, markdown to text, text to markdown, and print to PDF.
Markdown Table Generator — CSV/Excel to Markdown Tables (Free, Discord Mode)
Free markdown table generator: paste CSV, Excel or Google Sheets data and get clean GitHub-flavored markdown tables with alignment control, pipe escaping, line breaks, merge cells (HTML mode) and a Discord table mode. 100% private, in your browser.
Market Capitalization Calculator (Market Cap) — Price × Shares Outstanding
Compute market capitalization from share price × shares outstanding, with size classification (mega/large/mid/small/micro), fully diluted mode, a 2-company comparator, and a share price solver.
Markup Calculator — Markup to Margin Converter, Pricing & SKU Batch Tool
Free markup calculator: price from cost and markup, cost from price, two-way markup to margin converter, conversion table, discount-proof pricing and batch SKU pricelist. 100% client-side.
Mash Water Planner — Strike Water, Sparge Water, BIAB & Mash Tun Calculator
Free brew-day water planner: strike water temperature and volume calculator, sparge water calculator, BIAB full-volume mode, mash tun capacity check (can you mash it?), boil-off calibrator and recipe scaling. 100% client-side.
Mass to Mass Conversion Calculator & Unit Converter
Interactive mass to mass conversion calculator, conversion of units of weight, and grams to mass converter for science and labs.
Material Removal Rate Calculator — Turning, Milling & Drilling MRR (Free)
Free material removal rate calculator: turning, milling & drilling MRR in in³/min, cm³/min and mm³/min, plus machining time from volume. 100% in-brows
Math Step by Step Calculator & College Math Studio
Interactive math step by step calculator and college math calculator with algebra, calculus derivatives, and quadratic equations.
Free Math Worksheet Generator – Printable Worksheets with Answer Key
Generate free printable math worksheets online: addition, subtraction, multiplication, division, fractions, decimals, missing number & word problems. Automatic answer key, clean print layout, no sign-up. Perfect for teachers & homeschool.
Matrix Addition Calculator — Add Two Matrices Online (Free, With Steps)
Free matrix addition calculator: add two matrices of any size in an editable grid, with step-by-step c_ij = a_ij + b_ij, clear dimension-mismatch errors, copy and CSV download. 100% client-side, no signup.
Matrix Multiplication Calculator — Multiply Matrices with Steps
Multiply two matrices online: editable grids, per-element steps, dimension checks, copy & CSV.
Maturity Value Calculator — Deposits, Bonds
Compute maturity value of deposits, bonds, and debt notes: simple interest, compound interest, a 2-instrument comparison, and a principal/rate solver. Free, no signup.
Max Heart Rate Calculator — 4 Formulas + Training Zones | nrtechstudio
Estimate your max heart rate with 4 research formulas (Fox, Tanaka, Gulati, Gellish), see all 5 training zones in bpm, and find your fat-burning zone. Free, private, no sign-up.
Maximum Drawdown Calculator — Peak-to-Trough, Duration & Recovery
Compute maximum drawdown (MDD) from a portfolio value series or per-period returns. Includes drawdown duration, a 2-strategy comparator, and a recovery-gain solver. Free, 100% in-browser.
Mayan Numeral Converter — Decimal to Maya Glyphs
Convert decimal numbers to Mayan numerals and back. Dot = 1, bar = 5, shell = 0 in a vertical base-20 system, with a 0-19 glyph table and worked examples.
MB to GB Converter - Convert Megabytes to Gigabytes (Decimal and Binary)
Convert MB to GB and GB to MB instantly. Honest decimal (SI: 1 GB = 1000 MB) and binary (IEC: 1 GiB = 1024 MiB) modes, live KB MB GB TB PB panel, precision control, and real-world file size context.
MCG to IU Converter — Vitamin D, A & E (mcg ↔ IU, mg ↔ IU)
Free mcg to IU converter for vitamin D (1 mcg = 40 IU), vitamin A retinol (1 mcg = 3.33 IU) and vitamin E natural (1.49 IU/mg) / synthetic (2.22 IU/mg). Converts both directions with NIH-verified factors.
MCG to MG Converter: mcg, mg, g, kg Mass Units
Free mcg to mg converter (1 mg = 1000 mcg exact). Convert both directions between mcg, mg, g and kg with adjustable precision, step-by-step working, a quick label table and 15 FAQs.
mcg to mL Calculator: Dose, Concentration, and Volume
Free mcg to mL calculator with 3 modes: dose plus concentration to volume, volume plus concentration to dose, dose plus volume to concentration. Educational concentration math with unit selectors (mcg/mg/g, mcg/mL/mg/mL/g/L, mL/L).
Markdown AST Parser - Free Online Markdown Syntax Tree Explorer
Free Markdown AST parser — turn Markdown into an abstract syntax tree online. Collapsible tree view, exact line:col node positions, raw JSON with highlighting, GFM tables & task lists. 100% client-side.
Markdown Linter Online — Check Markdown Style Rules
Free online Markdown linter. Heuristic client-side checks for 15 markdownlint-style rules (MD001-MD047): headings, trailing spaces, blank lines, lists, code fences, line length. No uploads, no signup.
Markdown to BBCode Converter
Free Markdown to BBCode converter — convert Markdown to BBCode online with live preview. Headings, bold, italic, links, images, lists, tables, code and quotes for phpBB, vBulletin, MyBB and SMF forums. 100% client-side.
Markdown to Image Tag & HTML Converter
Standalone professional Markdown to HTML image converter and markdown img tag generator. Convert markdown image syntax to HTML with responsive options, lazy loading, and live preview.
Markdown to JSX Converter - Free Online React Component Generator
Free Markdown to JSX converter — turn Markdown into React components online with live editor, syntax map, copy & download .jsx. 100% client-side.
MD2 Generator — Free Online MD2 Hash Generator (RFC 1319)
Generate MD2 hashes from text or files entirely in your browser. Pure-JavaScript RFC 1319 implementation, batch mode, HMAC-MD2, uppercase/lowercase hex, and self-verifying test vectors. 100% client-side.
MD4 Generator — Free Online MD4 Hash Generator (RFC 1320)
Generate MD4 hashes from text or files entirely in your browser. Pure-JavaScript RFC 1320 implementation, batch mode, NTLM, HMAC-MD4, base64 output, and self-verifying test vectors. 100% client-side.
Mead Making Calculator Suite — Batch Planner, ABV, TOSNA Nutrients, Priming & More
Free mead making calculator suite: honey-to-gravity batch planner, ABV calculator (3 formulas), TOSNA 2.0/3.0 staggered nutrient scheduler, nutrient comparison, step feeding, backsweetening, stabilizer dosing, priming sugar & carbonation, fortification, blending, calories, dilution and hydromel. 100% client-side.
Meal Calorie Calculator — Calories & Macros Per Meal
Free meal calorie calculator: build your meal from 60+ common foods with USDA-based calories, get total calories plus protein, carbs and fat breakdown. 100% private, no signup.
Meal Prep Planner — Weekly Meals, Grocery List, Cost & Macros | nrtechstudio.com
Free meal prep planner: enter people, days and calorie targets to get your weekly meal count, auto-generated grocery list with quantities, cost estimate vs budget, daily macros and prep-time plan. 100% in your browser, no signup.
Mean Airway Pressure Calculator — MAPaw / Paw (Ventilator) | nrtechstudio
Free mean airway pressure (Paw / MAPaw) calculator for mechanical ventilation: time-weighted Paw from PIP, PEEP, Ti, Te; volume-control square-flow wa
Mean Free Path Calculator | nrtechstudio.com
Free mean free path calculator: compute λ = kB·T/(√2·π·d²·P) from temperature, molecular diameter and pressure — or solve inversely for pressure or te
Tool - Mean from Frequency Table Calculator
High-precision Mean from Frequency Table Calculator, grouped data statistics, weighted average, and online average calculator.
Mean Median Mode Calculator
High-precision Measures of Central Tendency Calculator: Mean, Median, Mode, Range, Quartiles & Visual Histogram.
Mean Sac Diameter Calculator — MSD to Gestational Age & Discriminatory Zone | nrtechstudio.com
Free mean sac diameter (MSD) calculator: average 3 gestational-sac ultrasound dimensions, estimate gestational age (MSD + 30 rule), and check the 25 m
Mean vs Median vs Average Calculator
High-utility statistics calculator and guide comparing mean, median, mode, and average with step-by-step formulas and interactive visual distribution.
Meat Carbon Footprint Calculator — How Much CO₂ Does Your Meat Habit Produce?
Free meat carbon footprint calculator: enter how much beef, lamb, pork, chicken, turkey, fish, dairy and eggs you eat to get your annual CO₂e, car-mile equivalents, and what-if swap scenarios. 100% private, runs in your browser.
Mechanical Advantage Calculator — Lever, Pulley, Incline & Screw | nrtechstudio
Free mechanical advantage calculator for the four simple machines: lever MA = L_in/L_out, pulley MA = rope segments n, inclined plane MA = L/h, screw
Medicine 3 Times a Day Calculator — Schedule & What It Means
Free medicine schedule calculator: what 1, 2, 3, 4 or 6 times a day means (every 24/12/8/6/4 hours), a dose interval planner, and general missed-dose
Meeting Cost Calculator: What That Meeting Really Costs
Free meeting cost calculator: enter attendees, hourly rates, and duration to see what a meeting really costs — per person, per minute, and per year if it recurs. Includes multi-tier rates and a salary-to-hourly converter.
Megawatt to kWh Calculator & Power to Energy Studio
Interactive megawatt to kwh calculator and mw to kwh calculator for electrical engineers, renewable energy planners, and utility analysts.
Melatonin Dosage Guide Calculator — How Much Melatonin Should I Take?
Melatonin dosage guide calculator: adult dose ranges (start low 0.5–1 mg, typically up to 5 mg), timing tips (30–60 min before bed), jet lag schedule,
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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.