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.
Auto Lease Calculator — Monthly Car Lease Payment Estimator
Free auto lease calculator: estimate your monthly car lease payment from MSRP, residual value, money factor, cap cost, taxes and fees. Includes money factor to APR converter and lease vs buy comparison.
Tool - Auto Loan Amortization Schedule & Car Payment Calculator
Universal automotive loan calculator, car payment interest calculator, vehicle loan amortization schedule, and loan payoff equation solver.
Tool - Average and Standard Deviation Calculator
High-precision statistical analysis suite featuring average and standard deviation calculator, summary statistics calculator, p-value from t-score calculator, and frequency distribution mean solver.
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.
Awning Size Calculator
Free awning size calculator: width, projection, pitch, mounting clearance, fabric & frame takeoff, and cost for wall-mounted awnings.
Baby Cost Lab — First-Year Baby Budget Calculator & Cost Suite
Free first-year baby budget calculator: build your year-1 total across 6 modes — budget builder, breastfeeding vs formula & childcare scenario comparator, birth cost with/without insurance, gear checklist budgeter, child tax credit estimator, and geo adjuster. 100% client-side, no signup.
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
Baby Formula Feeding Calculator — How Much Formula by Weight Age (AAP-Based)
Free baby formula feeding calculator: how much formula per day by weight (AAP 2.5 oz/lb rule) and by age (ml/kg method), ounces per feeding, feeding schedule by month, combination feeding, and formula cost per month. 100% client-side, no signup.
Baby Growth Percentile Calculator — WHO Length-for-Age & Weight-for-Length (0–24 Months) | nrtechstudio.com
Compute length-for-age and weight-for-length percentiles and z-scores for babies 0–24 months using the official WHO Child Growth Standards LMS tables.
Baby Percentile Calculator — WHO Weight-for-Age (0–24 Months)
Free baby weight percentile calculator using the official WHO Child Growth Standards (LMS method). Enter age, weight and sex to get percentile, z-score and growth category for babies 0–24 months.
Baby Sleep Schedule Calculator — Wake Windows by Age, Naps & Bedtime
Free baby sleep schedule calculator: generate a nap schedule by age with wake windows, explore wake windows 0–24 months, predict nap transitions (3→2→1), solve bedtime in reverse, and check total sleep vs AAP ranges. 100% client-side, no signup.
Baby's Milk Intake Calculator by Weight — How Much Milk Should Baby Drink
Calculate how much milk your baby needs per day by body weight (mL/kg): 0–6 months ~150 mL/kg/day (range 120–180), 6–12 months 500–700 mL/day. Includes per-feed amounts and mL to oz conversion. Educational guide, not medical advice.
CSS Liquid Gradient & Background Generator
Interactive background generator CSS with animated CSS liquid gradient, mesh blurs, and developer-grade CSS generators.
Backyard Chicken Egg Cost Calculator — Is It Cheaper to Raise Chickens for Eggs? | nrtechstudio.com
Free backyard chicken egg cost calculator: cost per dozen (year-1 vs ongoing), startup budget, best egg-laying breeds, store-vs-homegrown payback, feed cost optimizer, and local regulation checklist. 100% private — runs in your browser.
Bacon Curing Calculator — Prague Powder #1, Salt & Sugar by Weight (USDA ppm Limits)
Free bacon curing calculator: exact Prague Powder #1 (6.25% nitrite) in grams + teaspoons, salt and sugar for dry cure and wet brine, with USDA 9 CFR 424.22 ingoing nitrite limits (120 ppm wet / 200 ppm dry-cured bacon). Cure-time estimator by thickness.
Bacteria Growth Calculator — Doubling Time, OD600 & Growth Curve | NR Tech Studio
Free bacteria growth calculator: exponential growth N = N0 x 2^(t/g), doubling time from cell counts, time to reach a target population, OD600 to cells/mL estimate, and lag/log/stationary/death growth
Baker's Percentage Calculator — Convert Recipes to Baker's % & Scale Formulas
Free baker's percentage calculator: convert any bread recipe to baker's percentages (flour = 100%), compute true hydration including preferment, and scale any formula by flour weight or total dough weight. Levain, poolish & biga supported.
Baking Substitution Finder — 49 Ingredient Substitutes with Exact Ratios
Out of buttermilk, eggs, or butter? Find the exact baking substitution with precise ratios, dietary filters (vegan, dairy-free, gluten-free), and baker's adjustment notes. 49 ingredients, 100+ tested substitutes. Free, no signup, 100% client-side.
Ballistic Coefficient Calculator — SD, BC, G1/G7 Form Factor & Missing-Variable Solver
Free ballistic coefficient calculator: sectional density SD=m/d², BC=SD/i for G1 and G7 drag models, missing-variable solver (BC, SD, i, mass, diameter), typical form-factor table, unit converter, and
Balloon Payment Loan Amortization Schedule
Full amortization table calculator, balloon payment loan amortization schedule, car payment amortization calculator, mortgage amortization, auto finance, create amortization schedule.
Baluster Spacing Calculator — Even Layout, 4-Inch Rule Check (Stair & Level)
Free baluster spacing calculator: even baluster layout for level and stair railings, baluster count optimizer, 4-inch sphere rule (IRC) pass/fail check, newel post deduction, metric + imperial units, cut list. 100% client-side.
Bank Loan Calculator & Loan Percentage Rate Calculator
Free online bank loan calculator and loan percentage rate calculator. Calculate monthly payments, analyze loan repayment terms, inspect amortization schedules, and compute total interest.
Bar Stool Size Calculator — Height, Spacing & Fit (7 Modes)
What size bar stool do you need? Free 7-mode calculator: stool height, how many fit, spacing, layout, footrest height and knee space. Inches + cm.
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.
Barbell Plate Calculator (kg lb) — Visual Plate Loader
Free barbell plate calculator: enter your target weight and see exactly which plates to load per side, with a visual bar diagram, plate inventory mode, warm-up set generator, kg/lb units and fractional plates. 100% private, works offline.
Barn Size Calculator - Plan Horse Barns, Hay Storage & Build Cost
Free barn size calculator: plan horse stalls (12x12 ft), hay storage, tack & feed rooms, wash racks, equipment bay, full barn layout, and build co
Barthel Index Calculator — ADL Score (0–100 & 0–20 Scales)
Free Barthel Index calculator for activities of daily living (ADL). Score all 10 items on the original 0–100 scale (Mahoney & Barthel 1965) or the 0–2
Basal Area Calculator — Tree Basal Area, m²/ha & Stocking | nrtechstudio
Free basal area calculator: enter DBH to get per-tree basal area (cm², m², in², ft²), aggregate any fixed-area plot to m²/ha and ft²/acre, and estimate stocking with Reineke SDI. 100% client-side.
BASDAI Calculator — Bath Ankylosing Spondylitis Disease Activity Index
Free BASDAI calculator: answer 6 visual-analogue-scale questions (0-10) and get your Bath Ankylosing Spondylitis Disease Activity Index score, interpretation (active vs low disease activity), and question-by-question breakdown.
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.
Base16 to Base 10 – Universal Base Calculator & Numbering System Converter
Base16 to base 10, convert into hex, how to turn a mixed number into a decimal, base calculator, how to turn a mixed fraction into a decimal, deg min sec to decimal, int to hex, base to base conversion, base 10 calculator, convert the numeral to a numeral in base ten, convert base 2 to base 10, base 5 converter, base 6 converter, numbering system converter, 1a hexadecimal to decimal, 2a hex to decimal, 0x20 to binary, binary 111 to decimal, 100 to hexadecimal.
Base 2 (Binary) Converter & Calculator
Professional Base 2 Number Converter, Signed Binary Calculator, Two's Complement Solver, and Binary Arithmetic Engine.
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 to HEX Converter Online
Free online base64 to hex converter, hex to base64 calculator, and base64 to text decoder. Convert base64 to image, base64 to binary, and base64 to string.
Base64 to Image — Decode, View & Download Online
Free online Base64 to image decoder: paste a Base64 string or data URI, preview the image, detect its format and dimensions, download or copy it. 100% client-side.
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.
Base64URL to Hex Converter
Free Base64URL to hex converter — decode URL-safe Base64 into
Base64URL to String Decoder
Decode Base64URL (RFC 4648 section 5) back to text: padding-optional input, per-quartet decode math, strict UTF-8 validation, JWT segment detection, batch mode.
Base85 / Ascii85 Decoder
Enterprise-grade interactive Base85 and Ascii85 decoder, multi-variant encoder, and byte stream analyzer with 100% SEMrush keyword optimization.
Standalone - Baseball Glove Size Calculator
Free baseball glove size calculator: age-by-position size chart for infield, outfield, pitcher, catcher and first base, youth baseball glove sizer, fastpitch vs slowpitch softball glove sizes, catcher's mitt sizer, first base mitt guide, break-in advisor and glove fit check.
Basement Size Calculator — Room, Code Checks & Material Estimates | nrtechstudio.com
Basement size calculator: room area, IRC ceiling-height and egress-window code checks, plus flooring, insulation, lighting and paint estimates.
Bash to PowerShell Converter — Heuristic Line-by-Line Mapping
Convert Bash scripts to PowerShell free: heuristic line-by-line mapping (echo, ls, grep, export, if, for, curl) with honest per-line MAPPED/UNMAPPED flags. 100% client-side.
Basis Point (bps) Calculator — Convert bps to Percent & Decimal
Free basis point calculator: convert bps to percent and decimal, compute interest rate differences in bps, add/subtract bps to rates, plus reference taferensi cepat.
Bathroom Exhaust Fan Size Calculator (CFM) | nrtechstudio.com
Size a bathroom exhaust fan in CFM with HVI dual-method rules: 1 CFM/sq ft for small baths, fixture sizing for large, plus ceiling & duct corrections.
Battery Charge Time Calculator - Li-ion, Lead-Acid, LiFePO4, Solar & EV
How long to charge a battery? Free calculator with chemistry efficiency (Li-ion, LiFePO4, lead-acid), SoC range, taper model, EV kWh, solar, mAh/Wh modes.
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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.