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.
3D Print Shrinkage & Fit Calculator — FDM Tolerance, Clearance & Hole Compensation
Free 3D print shrinkage calculator: measure your test print and get the exact slicer scale factor, plus FDM clearance recommendations (press, snug, sliding, loose), hole & pin fit compensation, and a material shrinkage database for PLA, PETG, ABS, ASA, Nylon, TPU and PC. 100% client-side — your data never leaves the browser.
Probability Calculator for Independent Events
Probability calculator for independent events: P(A and B), P(A or B), complements, XOR, and 3+ event chains. Fraction, decimal & percent modes with steps.
Product Schema Markup Generator
Interactive Product & Offer Schema.org JSON-LD structured data builder for Google Shopping and e-commerce rich results.
Projectile Motion Calculator — Range, Max Height, Flight Time, Target Angles | nrtechstudio
Free projectile motion calculator: angled launch (range R=v₀²sin2θ/g, max height, flight time), launch angles to hit a target (0/1/2 solutions), inver
Projector Throw Distance Calculator & Screen Size Planner (Model-Agnostic) | Projector Throw Lab
Free model-agnostic projector throw calculator: throw ratio, throw distance, screen size, short-throw & UST mode, zoom-range visualizer, screen-size converter, and brightness sanity check. 100% client-side.
Prop Slip Calculator — Boat Propeller Slip % & Pitch Finder
Free prop slip calculator: compute propeller slip % from RPM, pitch, gear ratio and actual speed. Reverse mode finds the right pitch or RPM for a target slip. Mercury & Yamaha gear ratio presets, mph/knots/km/h, slip interpretation table. 100% in-browser, no sign-up.
PCB Propagation Delay Calculator — Trace Length to Time, Skew Matcher
Free PCB signal propagation delay calculator: convert trace length to flight time (ps/ns), delay budget to max length, match skew for DDR-style buses, and estimate via delay. Stripline and microstrip (Hammerstad-Jensen), 100% client-side.
Property Tax Lab — Property Tax Calculator by Mill Rate, State, Homestead Exemption & Land Transfer Tax
Free property tax calculator lab: mill-rate math, 50-state effective-rate database, homestead exemption estimator (FL $50k, TX $140k), property tax cap projector (CA Prop 13), Ontario & Toronto land transfer tax, and Australian stamp duty (NSW/VIC/QLD). 100% client-side.
Prorated Rent Calculator — Move-In & Move-Out Partial-Month Rent
Free prorated rent calculator: actual-days vs 30-day daily rates,
Prorated Salary Calculator — Mid-Month Hire, Termination & Raise
Free prorated salary calculator: mid-month hire/termination/raise,
Prostate Volume Calculator — Ellipsoid (TRUS/MRI)
Free prostate volume calculator using the ellipsoid formula (length × width × height × π/6 or ×0.52) from ultrasound or MRI dimensions. Includes PSA density, size interpretation, and worked example. Educational use only — not medical advice.
Protein Concentration Calculator — A280, Bradford/BCA, Unit Converter & Dilution
Free protein concentration calculator: A280 Beer–Lambert with a 10-protein extinction-coefficient database, Bradford/BCA standard-curve fit with R², mg/mL ↔ µM converter and C1V1 dilution planner. 100% client-side.
Protein-Creatinine Ratio Calculator (UPCR) — Spot Urine & ACR | nrtechstudio
Free UPCR calculator: compute the spot urine protein-to-creatinine ratio in g/g, mg/g, and mg/mmol, estimate 24-hour protein excretion, and classify n
Protein Molecular Weight Calculator — Sequence to MW, Extinction Coefficient | nrtechstudio
Free protein molecular weight calculator: paste an amino acid sequence to get MW in Da/kDa, extinction coefficient ε280 (Pace), A280 of 1 mg/mL, composition chart, unit converter and fusion-tag adjuster. 100% client-side.
PowerShell to Bash Converter — Heuristic Line-by-Line Mapping
Convert PowerShell to bash free: line-by-line mapping (Write-Host, Get-ChildItem, Select-String, if, foreach) with honest unmapped flags. 100% client-side.
Pseudonym Generator – Fake Person & Alter Ego Name Creator
Fake person generator, pseudonym generator, generate random key, randomizer app, alter ego name generator, random number generator 1 19, random name generator germany, fake name company generator, org name generator.
PSI Conversion Calculator (PSI to Bar, kPa, MPa, ATM)
Free psi conversion calculator. Convert psi to bar, kPa, MPa, ksi, atm, inHg, mmHg, torr, psf and kg/cm2, both directions. Exact constant: 1 psi = 6,894.757293168 Pa. Includes conversion charts, worked examples and FAQ.
PSI to GPM Calculator: Orifice Flow from Pressure Drop
Free PSI to GPM calculator. Convert pressure drop (PSI) to water flow rate (GPM) through an orifice or nozzle: GPM = 29.81 x Cd x d^2 x sqrt(dP). Includes reverse mode, discharge coefficients, orifice table, worked examples and FAQ.
PSIG to PSIA Conversion Calculator
Convert psig to psia and back. psia = psig + 14.6959. Enter your actual barometric pressure for precision, plus vacuum (psiv) conversion, worked examples, and 16 FAQs.
Psychrometric Calculator - Wet-Bulb, Dew Point, Enthalpy & Humidity Ratio
Free psychrometric calculator: enter dry-bulb temperature plus relative humidity, wet-bulb, dew point or humidity ratio to get enthalpy, specific volume, vapor pressure, air density and more. Interactive psychrometric chart. SI & IP units.
PT to PX Converter & EM to Pixels Studio
Interactive pt to px converter, 1em to px, 1 em in px, and convert em to pixels CSS typography unit tool.
Pulley Speed Calculator — Belt Drive RPM, Belt Length & Compound Ratios | nrtechstudio
Free pulley speed calculator: N2 = N1·D1/D2 speed-ratio solver (any 3 of 4), belt speed v = πDN, open-belt length L = 2C + π(D1+D2)/2 + (D2−D1)²/(4C),
Standalone - Pump Horsepower Calculator
Pump horsepower calculator: water HP and brake HP from GPM and total dynamic head, NEMA motor sizing, wire-to-water effi
Punycode Converter — Unicode ↔ Punycode (IDN) with Homograph Phishing Detector
Free online Punycode converter: Unicode to Punycode and Punycode to Unicode per RFC 3492, full domain & URL mode, batch conversion, plus an IDN homograph phishing detector. 100% client-side — nothing leaves your browser.
Puppy Weight Calculator — Predict Your Puppy's Adult Weight
Free puppy weight calculator: enter your puppy's age and current weight, pick a breed size class, and get a predicted adult weight range from veterinary growth curves, with classic doubling-rule cross-checks.
Push-Ups Calorie Calculator — Calories Burned Per Rep & Per Workout
Free push-up calorie calculator: enter reps or workout time plus body weight and intensity to estimate calories burned, calories per push-up, and food equivalents. MET values verified from the Compendium of Physical Activities. 100% private, no signup.
Putting Green Size Calculator — Backyard Golf Green Planner
Size a backyard putting green: green dimensions from your space, shape planner, turf takeoff, base and drainage, cups, slope advisor and DIY vs pro cost. 100% client-side.
Px To Em
Convert CSS Pixels to EM units.
Python pyproject.toml Generator
Interactive Poetry pyproject.toml generator, Python PEP 621 config maker, and dependency builder.
Pyramid Frustum Calculator — Volume & Surface Area (Square & Rectangular)
Free pyramid frustum calculator: volume, lateral and total surface area of a square or rectangular frustum of a pyramid. Enter top/bottom sides and height or slant height — with step-by-step working and diagram.
Python Code Formatter
Python Code to Text Converter
Interactive converter that transforms Python source code into plain text explanations, pseudocode, and documentation.
Python JSON to CSV Converter
Convert JSON to CSV online and generate production-ready Python code using Pandas json_normalize and native csv modules.
Python Pad String with Spaces & YAML Parser
Interactive developer tool for Python string padding, YAML parser, YAML formatter online, JSON to YAML converter, and HTML escape utilities.
qSOFA Score Calculator — Quick Sepsis Screening (Sepsis-3) | nrtechstudio
Free qSOFA calculator (Seymour et al., JAMA 2016, Sepsis-3): respiratory rate ≥22/min, altered mentation (GCS <15), systolic BP ≤100 mmHg — score 0
qPCR Efficiency Calculator — Slope to Efficiency %, Standard Curve & Troubleshooter
Free qPCR efficiency calculator: convert standard-curve slope to efficiency % (E = 10^(−1/slope) − 1), fit a 5–7 point standard curve with R² and outlier detection, or compute efficiency from dilution-series Ct values. With troubleshoot advisor, worked examples, and honest limitations. 100% client-side.
QR Code Generator — Free Custom QR Codes
Free QR code generator: create custom QR codes for URLs, text, WiFi, vCards, email and SMS. Error correction levels, custom colors, PNG and SVG download. 100% client-side.
QTc Calculator — Corrected QT Interval (Bazett, Fridericia, Framingham, Hodges)
Free QTc calculator: correct the QT interval for heart rate with four formulas — Bazett, Fridericia, Framingham (Sagie) and Hodges. Sex-specific inter
Quadratic Equation Solver — Step-by-Step with Graph | nrtechstudio.com
Free quadratic equation solver: solve ax²+bx+c=0 with full step-by-step working (discriminant, quadratic formula, factoring, completing the square), parabola graph, vertex and factored forms. Handles complex roots. 100% in your browser.
Quarter Calc
Determine which fiscal quarter a date falls in.
Quarter Circle Perimeter Calculator — Formula, Arc Length & Worked Steps | nrtechstudio.com
Free quarter circle perimeter calculator: enter radius, diameter, or area to get perimeter P = πr/2 + 2r, arc length, quarter-circle area, a labeled SVG diagram, and step-by-step working.
Quarter Mile Calculator — ET & Trap Speed Estimator
Free quarter-mile calculator: estimate 1/4-mile ET and trap speed from weight and horsepower using the Huntington, Hale, and Fox formulas. Includes reverse HP solver, 1/8-mile estimate, whp/crank correction, and ET class table. 100% client-side.
Quarts to Pounds Converter (qt to lb via Density)
Convert quarts to pounds and pounds to quarts with density. US liquid, US dry, and imperial quarts. Presets for water, milk, oil, honey, flour, sugar plus custom density.
Quartz to Cron — Convert Java Quartz Cron to Linux Cron
Convert Java Quartz cron expressions to Linux crontab online. Paste a 6- or 7-field Quartz expression, get the 5-field Linux cron with field mapping, validation and honest approximation warnings. Free, 100% client-side.
Query String Parser & URL Analyzer Studio
Interactive query string parser and urlparse javascript inspector for web developers, API engineers, and SEO specialists.
Quilt Math Lab — Quilt Yardage, Binding, Backing, HST Precut Calculators
Free quilt calculator suite: quilt yardage planner, binding calculator (straight-grain + continuous bias), backing layout optimizer for 44" vs 108" fabric, HST/QST/flying-geese/on-point block math, jelly roll / charm / layer cake / fat quarter precut lab, and rag quilt calculator. 100% client-side.
Rabbit Cage Size Calculator — Hutch, Run & Enrichment (RWAF/RSPCA)
Free rabbit cage size calculator: ideal footprint for 1-8 rabbits by breed size (RWAF 3x2x1 m minimum), ft²↔m² converter, hutch + run combo checker, and enrichment checklist. 100% client-side.
Rabbit Color Calculator — Predict Kit Coat Colors from Parent Genotypes
Free rabbit coat color genetics calculator: predict kit colors from sire & dam genotypes across the 5 main loci (A, B, C, D, E), browse the color library, reverse-lookup genotypes, and learn the allel
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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.