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.
Braden Score Calculator — Pressure Ulcer Risk
Free Braden Scale calculator: score 6 subscales (sensory perception, moisture, activity, mobility, nutrition, friction & shear) to estimate pressure injury risk. Score 6–23 with risk interpretation. Educational tool, not a substitute for clinical assessment.
Bradford Factor Calculator — nrtechstudio
Free Bradford Factor calculator (UK). Enter absence spells (S) and total days absent (D) to get the score B = S² × D, with interpretation bands, a reverse planner, and a multi-employee ranking table. 100% client-side — your data never leaves your browser.
Bragg\
Bragg's law calculator nλ = 2d·sinθ for X-ray diffraction (XRD): compute λ, d-spacing, θ / 2θ, and order n. Cu Kα, Mo Kα, Co Kα anode presets. Free, 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.
BMEP Calculator (Brake Mean Effective Pressure) — From Torque, Power & Target
Free BMEP calculator: compute brake mean effective pressure from torque or from power & RPM (2-stroke/4-stroke), plus a reverse mode from a BMEP target to torque & power. Units: bar, psi, kPa. 100% client-side.
Break-Even Calculator — Social Security, Business & Two Scenarios
Free break-even calculator: Social Security claiming break-even age (62 vs 67 vs 70), business break-even units, and two-scenario cost comparison. 100% client-side.
Circuit Breaker Size Calculator — What Size Breaker Do I Need?
What size breaker do I need? Enter watts, VA, amps, or HP (120–600V, 1-phase or 3-phase) and get the NEC 240.6 standard breaker size with 125% continuous-load sizing plus a companion wire recommendati
Breast Cancer Recurrence Risk Estimator (Educational) — NR Tech Studio
Free educational estimator that scores commonly-discussed breast cancer tumor factors (stage, grade, nodes, size, hormone status, HER2) on an illustrative 0–100 scale. Not a clinical prediction — validated tools like PREDICT and Oncotype DX are used by doctors.
Breast Cancer Risk Estimator — 5-Year & Lifetime (Simplified Gail Model)
Educational breast cancer risk estimator based on a simplified Gail model (BCRAT): 5-year and lifetime risk from age, age at menarche, age at first birth, family history, and breast biopsies. Estimate only — not medical advice.
Breastfeeding Calorie Calculator — Daily Calorie Needs While Nursing
Estimate how many calories you need while breastfeeding: BMR (Mifflin-St Jeor) + activity + IOM lactation allowance (330 kcal/day for months 0-6, 400 kcal/day for months 7-12), with an optional safe weight-loss target.
Brew Cost Calculator — Homebrew Cost Per Bottle + "Is It Cheaper?" (Free)
Free homebrew cost calculator: build your batch cost from grain, hops, yeast, water and energy, get cost per bottle / pint / liter, compare vs store beer prices, amortize equipment, and scale recipes. 100% client-side, no signup.
Brewster Angle Calculator (Polarization) — nrtechstudio.com
Compute the Brewster angle θ_B = arctan(n₂/n₁): the incidence angle at which p-polarized reflection becomes zero. Inverse mode: determine the refractive index from a measured Brewster angle. Free, 100% client-side.
BRI Calculator — Body Roundness Index
Calculate Body Roundness Index (BRI) from waist and height. Compare BRI vs BMI, solve target waist, and explore the ellipse model. Free, private.
Brick Calculator
Brick calculator: how many bricks, mortar bags & cost for any wall, pillar, or arch. US/UK/AU brick sizes, courses & ASTM C270 mortar. Free, c
Bridge Rectifier Calculator — AC-to-DC Bridge Rectifier Design
Free bridge rectifier design calculator: compute Vpeak, Vdc, ripple, PIV, and filter capacitor needs from transformer specs. Bridge & half-wave modes, 50/60 Hz, 100% client-side.
Brine Calculator
Brine calculator: exact salt per liter of water for any brine concentration; fermentation, pickling and de-icing brine with freezing-point estimates.
Broad-Crested Weir Discharge Calculator
Compute discharge (Q), head (H), or crest width (b) of a broad-crested weir. SI & imperial units, 100% client-side, free.
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.
Euler Column Buckling Calculator — Critical Load & Slenderness Ratio
Free Euler column buckling calculator: compute critical load P_cr = π²EI/(KL)², critical stress, slenderness ratio λ = KL/r, and the Euler vs Johnson validity limit. Steel, aluminum, wood, concrete presets.
build.gradle Generator
Free online build.gradle generator - Groovy and Kotlin DSL build file builder with plugins, dependencies, repositories, presets and custom tasks.
Bulb Spacing Calculator — How Many Bulbs to Plant & How Deep | nrtechstudio
Free bulb spacing calculator: pick a bulb type, enter your bed size, and get exact planting distance, depth, and how many bulbs to buy. Grid and staggered layouts, 18 bulb types.
Bulk Modulus Calculator - K from Compression, Elastic Relations & Sound Speed
Free bulk modulus calculator: K = -V(dP/dV) from compression data, full isotropic elastic-constant solver (K, E, G, Poisson's ratio), and sound speed c = sqrt(K/rho). Material presets included.
Bullet Energy Calculator — Muzzle Energy & Downrange | nrtechstudio.com
Free bullet energy calculator: compute muzzle energy in ft-lbs and joules from bullet weight (grains) and muzzle velocity (fps). Includes downrange energy calculator with ballistic coefficient, caliber comparison chart, and the muzzle energy formula explained.
BUN/Creatinine Ratio Calculator — Free Azotemia Pattern Tool | nrtechstudio
Free BUN/creatinine ratio calculator: enter BUN and creatinine in mg/dL or SI units, get the ratio with classical prerenal / normal / intrarenal patte
Buoyant Force Calculator — Archimedes\
Free Archimedes buoyant force calculator: compute F_b = ρ × V × g, apparent weight of a submerged object, and floating volume fraction. Fresh water, sea water, oil, air presets. 100% client-side.
Burn Rate Calculator — Gross vs Net Burn, Runway & Fundraise Target (Free)
Free startup burn rate calculator: derive gross & net burn from bank balances, project runway & zero-cash date, size your fundraise. 100% in-browser.
Business Loan Calculator — Payments, Balloon Payment, Fees & Affordability
Business loan calculator: estimate working capital/expansion loan payments, balloon payment, origination fees (effective vs nominal APR), and loan limits from cash flow with a 1.25× DSCR guard.
Business Profit Tax Calculator & Stock Capital Gains Studio
Interactive business profit tax calculator and tax calculator for stocks across corporate and investment brackets.
Small Business Valuation Calculator — 3-Method Business Value Estimate
Free business valuation calculator: estimate small business value with revenue multiple, SDE multiple, and simple DCF methods, plus a 3-method comparator. 100% client-side.
cJSON Code Generator
Generate C/C++ parsing and serialization code using the DaveGamble cJSON library from any JSON payload.
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
Caffeine Calculator — Half-Life, Sleep Cutoff, Safe Limit & Pet Toxicity
Free caffeine calculator lab: track daily intake, visualize half-life decay over time, find your last-coffee cutoff before bed, check your personal safe limit (FDA/EFSA), browse a 64-drink caffeine database, and check caffeine toxicity for dogs & cats. 100% client-side.
CAGE Questionnaire — 4-Question Alcohol Screening Calculator
Free CAGE questionnaire alcohol screening: answer the 4 official CAGE questions (Cut down, Annoyed, Guilty, Eye-opener; score 0-4, cutoff ≥2). Screeni
Cake Pan Conversion Calculator — Pan Size, Batter & Bake Time Converter
Convert cake recipes between pan sizes with batter-depth checks and bake adjustments.
Cake Serving Calculator — Servings, Batter & Frosting Planner
How many servings per cake pan, batter cups and frosting amounts from the Wilton serving guide. Two-way solver, tiered planner, metric + US.
Calculate Age & Chronological Age Calculator
High-precision calculate age from date of birth, chronological age calculator, age in months/days/weeks, age comparison, and leap year handling.
Calculate Birth Year from Age & Exact Age Calculator
Interactive birth year calculator, age finder by year, and exact age month day calculator with generation and life milestone analysis.
Calculate Test Statistic Calculator & Hypothesis Testing Studio
Interactive calculate test statistic calculator, statistical probability calculator, critical z value solver, and statistical values calculator online.
Calculator for Employer Payroll Taxes & W-4 Suite
Interactive calculator for employer payroll taxes, W-4 withholding calculator, additional tax withholding, and tax afterpay installment planner.
Fractions with Exponents & Mixed Number Calculator
Free calculator for fractions with exponents, mixed number to decimal converter, and recurring decimal to fraction solver with steps.
Tool - Free Scientific & Graphing Calculator
All-in-one free online scientific calculator, graphing display calculator, engineering notation, trigonometry, logarithm, physics, and statistical calculator.
Calculator with Fraction
Universal Fraction Calculator, Step-by-Step Multiplication, Division, Subtraction & Fraction Squared Solver.
Tool - Calendar Calculator & Calendar Year Inflation Calculator
Universal calendar calculator and historical calendar year inflation calculator. Computes US CPI dollar value, year to year purchasing power, cumulative inflation rate, and wage comparison.
California Overtime Calculator — 8/12/40 & 7th-Day Rules
Calculate California overtime pay: 1.5× after 8 hrs/day, 2× after 12 hrs/day, 1.5× after 40 hrs/week, plus the consecutive 7th-day premium. Compare against federal FLSA rules.
Calorie Calculator — Daily Calorie Needs & Macro Split
Free calorie calculator: estimate daily calorie needs with the Mifflin-St Jeor equation, 5 activity levels, and goals to lose, maintain, or gain weight — plus a simple protein, fat, and carb split.
Calorie Deficit Calculator — Daily Deficit for Weight Loss
Calculate your daily calorie deficit for weight loss: enter kg to lose and weeks to get the daily deficit, or enter a deficit to see your timeline. Safety bands 500-750 kcal/day, intake floors, weekly projection.
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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.