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.
SHA-1 Hash Generator & Checksum Calculator
Standalone professional SHA1 generator, SHA1 hash calculator, and SHA1 calculator. Generate SHA1 checksum for text, inspect SHA1 hash examples, and run hash generator SHA1 with zero AI slop.
Shade Sail Size Calculator
Free shade sail size calculator: sail dimensions, attachment layout, post heights, hypar twist, hardware takeoff, shade % and cost for 3- or 4-point sails.
Shaft Size Calculator (Shaft Size) — Power to Diameter, DIN 6885 Keyway, Critical Speed
Free shaft size calculator: motor power (kW/HP) + RPM becomes torque then minimum diameter, DIN 6885 keyway, metric/inch standard shaft sizes, and critical speed. 100% client-side.
Shannon Index Calculator — Shannon Diversity Index (H'), Evenness & Simpson
Free Shannon index calculator: compute Shannon diversity index H' = -sum(p_i * ln(p_i)), Pielou evenness J', species richness, and Simpson index from species counts. Compare two communities. 100% clie
Shear Stress Calculator — τ=V/A, τ=Tr/J, τ=VQ/Ib
Free shear stress calculator: direct shear τ=V/A, torsion τ=T·r/J for solid/hollow shafts, and beam bending shear τ=V·Q/(I·b). Pa, kPa, MPa, psi, ksi conversion.
Shed Size Calculator — Equipment Sizer, Doors, Foundation & Permits
What size shed do you need? Free 7-mode calculator: equipment sizer, stock sizes, door & walkway clearance, foundation, permits and costs.
Sheep Gestation Calculator — Ewe Due Date & Lambing Calendar | nrtechstudio.com
Free sheep gestation calculator: enter the breeding (tupping) date to get the expected lambing due date, live countdown, pregnancy milestone timeline, flock batch planner, lambing signs and lambing kit checklists. 100% private — runs entirely in your browser.
Shell Escape — Quote Strings Safely for Bash, CMD & PowerShell
Shell escape tool: safely quote strings for bash, sh, cmd & PowerShell. Single-quote, backslash & double-quote modes, char-by-char view. 100% client-side.
Shell Unescape — Strip Quoting Back to Raw Text
Shell unescape tool: strip bash, sh, cmd & PowerShell quoting back to raw text. Auto-detect mode, 5 unescape modes, argv split view. 100% client-side.
Shock Index Calculator — SI, Modified Shock Index & Age SI
Free shock index calculator: enter heart rate, systolic and diastolic blood pressure to get the shock index (HR/SBP), mean arterial pressure, modified
Short Link Generator & Hyperlink Shortener
Free short link generator and hyperlink shortener. Create clean, short URLs, custom slug aliases, and QR codes instantly with zero registration.
Shower Cost Calculator
Shower cost calculator: per-shower water + energy cost by heater type (DOE EF), shower vs bath break-even, and shower remodel cost estimator.
Sideboard Size Calculator — Width, Height & Depth for Buffets | nrtechstudio.com
What size sideboard do I need? Free sideboard size calculator: width from your table or wall, height, depth and clearance checks — inches and cm.
Siding Replacement Cost Lab — Estimate Your Project + 30-Year True Cost
Free siding cost calculator: enter your home
Signal-to-Noise Ratio (SNR) Calculator — Power, Voltage, Friis Cascade, ENOB & Shannon
Free SNR calculator: calculate signal-to-noise ratio from power (W/mW/dBm) or voltage, cascade degradation, ENOB, and Shannon capacity. 100% client-side.
Significant Figures Counter & Rounding Calculator
Free significant figures counter: count sig figs in any number, see which digits are significant, which rule applies, and round to N significant figures — 100% client-side.
Silver Melt Value Calculator — Sterling, Coin & Fine Silver
Free silver melt value calculator: scrap silver by weight and purity
Simple Interest Calculator — Interest on Loans, Solver & Comparison
Free simple interest calculator: interest and total with I = P x r x t, time in days/months/years, reverse solver, monthly accrual schedule and simple-vs-compound comparison. 100% client-side.
Simplify Radicals Calculator — Simplify √, ∛ & nth Roots Step by Step
Free simplify radicals calculator: reduce √72 to 6√2, ∛54 to 3∛2 and any ⁿ√x to simplest a·ⁿ√b form with prime-factorization steps. Add and subtract like radicals too.
Sims Name Generator – Character, Nicknames & Stylized Fonts
Sims name generator, text generator font, screen name generator, fun text generator, online nicknames generator, free nickname generator, display names generator, random name picker app, last name generator english, stylized text generator, cool name maker, special letter generator, ff nickname generator, fictional company names generator.
Site Web Portfolio Generator & Showcase
Interactive web portfolio builder, frontend portfolio showcase, and curated design portfolio website examples.
XML Sitemap Generator — URL List to Valid Sitemap XML (Free)
Free XML sitemap generator: paste your URL list and get valid sitemap XML — auto-split sitemap index, image sitemap support, strict validation. 100% client-side; your URLs never leave the browser. Does not crawl websites.
Sitemap Parser — Extract URLs from XML Sitemap
Free online sitemap parser: paste XML sitemap or upload a .xml file to extract all URLs with lastmod, changefreq and priority. Export CSV or TXT. 100% client-side.
Skateboard Size Calculator — Deck Width, Truck & Wheel Size Finder
Free skateboard size calculator: deck width from shoe size, age and riding style, truck size matcher, wheel size guide and kids sizing chart.
Ski Length Calculator — Height, Weight, Skill, Poles, Boots & DIN
Free ski length calculator: height, weight, skill level and ski type to ski length, plus kids ski sizer, pole length, boot mondo converter, DIN reference and effective edge explainer.
Skin Depth Calculator — δ Copper, Aluminum, Iron, Steel + Graph
Free skin depth calculator: δ = √(ρ/πfμ) for copper, aluminum, iron, steel. 6 material presets + custom, temperature correction, AC/DC resistance ratio.
Sleep Cycle Calculator: Best Bedtime & Wake-Up Times (90-Minute Cycles)
Free sleep cycle calculator: enter the time you must wake up and get the best bedtimes (or enter bedtime and get the best wake-up times) based on 90-minute sleep cycles. Includes sleep duration by age, sleep-stage explainer, and nap planner. 100% client-side — your data never leaves your browser.
Sleep Debt Calculator: Track & Repay Your Cumulative Sleep Deficit
Free sleep debt calculator: log your nightly sleep, see your cumulative deficit vs your personal sleep need, chart 14 days, and get an honest payoff p
Slot Car Gear Ratio Calculator + Rollout Lab (48 vs 64 Pitch) | nrtechstudio
Free slot car gear ratio calculator and rollout lab: pinion/spur ratio solver, rollout & scale speed from tire diameter and motor RPM, target-ratio combo finder, interactive 1/32 gear chart, 48 vs 64 pitch explainer and track gearing advisor. 100% client-side.
Small Business Tax Calculator – LLC, Freelancer & Sales Tax
Small business tax calculator, wa tax calculator, how to determine sales tax, ma sales tax calculator, georgia state tax calculator, how much would i pay in taxes calculator, how much taxes will i owe calculator, how to find tax on an item, how to calculate sales tax percentage from total, agi tax calculator, tax calculator llc, self employed tax return calculator, how to figure tax on purchase, american sales tax calculator, tax rate calculator california, tn income tax calculator, tax calculator for freelancers, llc tax calculator with deductions, how to find tax on a calculator, how to calculate sales tax on a calculator, how to figure out tax on a calculator, convert sales tax, formula for figuring sales tax, sales tax and tip calculator, sell tax calculator, sales tax calculator usa.
Small Claims Court Worth It Calculator — Expected Value by State (2026) | nrtechstudio.com
Is small claims court worth it for your claim? Free calculator: expected value from claim amount, win odds, state filing fees (all 50 states + DC), time cost, and collection risk. Plus demand letter generator. Educational estimates, not legal advice.
Smoking Recovery Timeline — Recovery Timeline After Quitting Smoking
Enter your quit date and see where you stand on the health recovery timeline: from 20 minutes to 15 years, based on American Cancer Society data.
Snake to Pascal Converter
High-Performance Snake Case to Pascal Case Converter, Identifier Transformer, and Code Case Formatter with 100% SEMrush keyword optimization.
Snow Load Calculator — ASCE 7-22 Roof Snow Loads
Free ASCE 7-22 snow load calculator: flat roof pf, sloped roof ps with Cs, drift, unbalanced loads, psf to kPa converter.
Snowboard Length Calculator — Board Size, Waist Width & Stance Finder
Free snowboard length calculator: board size from weight, skill and riding style, waist width from boot size, stance width and angles, kids sizing, camber vs rocker guide and flex rating.
Snowshoe Size Calculator — Find Your Perfect Snowshoe Size & Fit
Free snowshoe size calculator: enter body + gear weight, snow conditions and terrain to get the right snowshoe size. Real manufacturer charts (MSR, Tubbs, Atlas, Yukon Charlie's, TSL), binding fit guide, kids & women's sizing.
Soap Making Cost Calculator — COGS, Pricing & Break-Even Suite
Free soap making cost calculator: build your true cost per bar from supplier prices (oils, lye, fragrance, packaging), add labor & overhead, price by margin, markup or wholesale 2x/4x, check Etsy, Shopee and Tokopedia fees, compare making vs buying, and find break-even. 18 currencies. 100% client-side, no signup.
Soap Lye Calculator — Lye, Recipe & Mold Suite for Soap Makers
Free soap lye calculator suite: NaOH/KOH/dual-lye recipes from 200+ oils, 3 water modes, lye purity correction, citric acid, mold-to-recipe, liquid soap dilution, batch scaler, fragrance rates, quality predictions and cure dates. 100% client-side.
Sobriety Calculator — Days Sober Counter, Milestone Chips & Money Saved
Free sobriety calculator and live days-sober counter. Enter your quit date to see your sober time ticking live, milestone chip timeline (24 hours, 30/
Sock Size Calculator — Cast-On, Heel & Foot Size Chart for Knitters
Free sock size calculator for knitters: cast-on stitches from foot circumference × gauge with negative ease, heel flap + row-by-row heel turn schedule, gusset pickup math, toe-up mode, foot length chart by shoe size (US/UK/EU), cuff & leg planner and yarn estimate. 100% client-side.
Sod Calculator — How Much Sod Do I Need? Rolls, Pallets & Cost | nrtechstudio.com
Free sod calculator: enter your yard dimensions to get square feet, sod rolls and pallets needed (with waste factor), plus cost estimates. L-shape, circle, polygon and sod vs seed comparison included. 100% private — runs in your browser.
SOFA Score Calculator — Sequential Organ Failure Assessment (0–24) | nrtechstudio
Free SOFA score calculator (Vincent et al. 1996): six organ systems scored 0–4 (PaO2/FiO2, platelets, bilirubin, MAP/vasopressors, GCS, creatinine/uri
Solar Panel Calculator — Size, Cost, Savings Payback (Global)
Free solar panel calculator: size your system from your electric bill (kWh, peak sun hours), estimate 25-year savings with degradation and tariff inflation, payback year, LCOE, battery backup, RV/campervan off-grid, tilt angle, and CO2 offset. Works worldwide, 20 currencies. 100% client-side.
Solenoid Inductance Calculator — Wheeler, Nagaoka & Wire Estimator
Free solenoid inductance calculator: Wheeler formula, long-solenoid SI formula, Nagaoka end-correction, wire length, copper AWG DC resistance, LC resonant frequency, and a turns-for-target-L design mode. 100% client-side.
Solenoid Magnetic Field Calculator
Free solenoid magnetic field B calculator: ideal solenoid B = μ₀NI/L, finite solenoid along the axis, single loop & Helmholtz pair, energy density B²/2μ₀ and core force. 100% client-side, with B(x) profile chart.
Sound Absorption Coefficient & RT60 Calculator — 24 Materials, Frequency Graph
Free sound absorption coefficient (α) calculator: calculate RT60 reverberation time with Sabine formula
Sous Vide Time Temperature Calculator — Baldwin-Based Pasteurization Times
Free sous vide time and temperature calculator based on Douglas Baldwin's pasteurization tables. Steak, chicken, pork, salmon, brisket, eggs — thickness, frozen & doneness aware. 100% client-side, no signup.
Space Travel Calculator — 1g Travel Time, Relativistic Rocket & More
Calculate space travel times: 1g flip-flop maneuvers, relativistic rockets, constant-velocity cruise with time dilation. Real physics.
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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.