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.
Fake Name & Profile Generator
Enterprise-grade fake user profile generator for UI testing, mock data synthesizer, and international profile generator with 100% SEMrush keyword optimization.
False Negative Pregnancy Test Calculator — How Likely Is a Missed Detection?
Estimate the chance of a false negative pregnancy test by days past ovulation (DPO), test sensitivity (10/20/25 mIU/mL) and urine timing. Based on pub
What Is My Relative to Me? — Family Relationship Finder
Type 'my cousin's daughter' or 'my mom's cousin' and get the exact relationship name — first cousin once removed, second cousin, great-aunt — with a plain-English explanation, family tree diagram, shared DNA %, and an interactive cousin chart. Free, private, no sign-up.
FAQ Schema Markup Generator
Interactive FAQPage Schema.org JSON-LD generator with live Google SERP preview and validation.
Faraday to Coulomb Converter & Electrolysis Calculator
Convert faraday to coulomb, kilocoulomb, milifaraday & ampere-hour. Calculate mass deposited with Faraday
Fatigue Severity Scale (FSS) Calculator: 9-Item Fatigue Score | nrtechstudio.com
Free Fatigue Severity Scale (FSS) calculator (Krupp et al. 1989): answer the 9 items rated 1-7, get your total, mean score, per-item breakdown, and th
Favicon Generator — Free Multi-Size ICO + PNG Maker (No Upload)
Free favicon generator that runs 100% in your browser: make a favicon from an image, text, emoji or initials. Exports 16x16, 32x32, 48x48, apple-touch-icon, 192 & 512px PNGs plus a real multi-size favicon.ico, HTML snippet and web manifest. No upload, no signup.
FCR Calculator — Feed Conversion Ratio for Poultry & Livestock
Free FCR calculator: compute feed conversion ratio for broilers, layers, pigs, cattle, tilapia and more. Includes target feed planner, cost per kg of gain, mortality-adjusted & economic FCR, and a multi-batch tracker.
Feedline Lab — Coax Loss Calculator, dBm to Watts, S-Unit & ERP Suite
Free feedline lab: coax loss calculator for 13 cable types (LMR-400, RG-213, 9913, HELIAX…), cable chooser, dBm↔watts converter, S-unit converter, ERP/EIRP calculator and a printable coax loss chart. 100% client-side, no signup.
Tool - Feet and Inches to Cm Converter
Universal metric conversion calculator for feet and inches to cm, meters to feet, height converter, and area conversions.
Feet to Yards Conversion: Convert ft to yd and yd to ft Calculator
Free feet to yards conversion calculator. Convert feet to yards (divide by 3) or yards to feet (multiply by 3), with a feet to yards chart, formula, football field and construction examples.
Female Name Generator – Baby Girl, Womens & Exotic Names
Female name generator, baby girl name generator, womens name generator, fantasy monster name generator, exotic name generator.
FENa Calculator — Fractional Excretion of Sodium (Prerenal vs ATN) | nrtechstudio
Free FENa calculator: fractional excretion of sodium to help distinguish prerenal AKI from intrinsic renal injury (ATN), plus a FEUrea mode for patien
Fence Calculator — Posts, Pickets, Concrete & Cost Estimator
Free fence material calculator: wood privacy, picket, chain link, vinyl & metal fences. Multi-run L-shape layout, gate planner, farm/acre mode, electric fence mode, concrete per post & cost estimator. 100% private — runs in your browser.
Fence Post Size Calculator — Depth, Concrete, Post Size & H-Brace | nrtechstudio.com
Fence post size calculator: hole depth (1/3 rule + frost line), concrete per post, 4x4 vs 6x6 picker, post schedule, H-brace planner and spacing chart
Fence Stain Calculator
Free fence stain calculator: gallons of stain for a wood fence, post & rail adder, coats, cost and drying time.
Fermi Level Calculator — Free Electron Gas Fermi Energy
Interactive Fermi level calculator: E_F from electron density n (2-way E_F↔n solver), Fermi temperature T_F, Fermi velocity v_F, Fermi momentum, plus verified metal presets (Cu, Al, Ag, Au, Na).
Fertility by Age Calculator — Monthly Chance, 12-Month Odds & IVF Success Rates | nrtechstudio.com
Estimate monthly fecundity rate, 12-month conception chance, and IVF live-birth rates by female age. Population estimates from ASRM/ACOG data — not a
Fertilizer Calculator — NPK Rate, Bags Needed & Cost | nrtechstudio.com
Free fertilizer calculator: enter your lawn or garden area, target nitrogen rate and N-P-K analysis to get exact product pounds, bags needed, nutrient breakdown, cost estimate and spreader settings. Works in imperial and metric.
Fetal Weight Percentile Calculator — Hadlock EFW by Gestational Week
Free fetal weight percentile calculator. Enter ultrasound biometry (BPD, HC, AC, FL) and gestational age to get estimated fetal weight (Hadlock 1985), weight percentile vs the Hadlock 1991 growth standard, an interactive growth curve, and SGA/AGA/LGA screening classification.
FEV1/FVC Ratio Calculator — GOLD Interpretation + NHANES III % Predicted
Calculate the FEV1/FVC ratio from spirometry: GOLD criteria interpretation (< 0.70), % predicted & LLN via NHANES III reference equations, and GOLD severity grades 1–4. Free, 100% client-side.
FF Name Generator & Gaming Nickname Studio
Free Fire name generator, stylish gamer tags, fancy Unicode fonts, and cool name generator for games.
FFMI Calculator — Fat-Free Mass Index (Raw + Normalized)
Free FFMI calculator: fat-free mass index with normalized FFMI (Kouri et al. 1995), visual gauge, research-backed categories, and a built-in US Navy body-fat estimator. Private — runs entirely in your browser.
FHA Loan Calculator — Monthly Payment, UFMIP & MIP
FHA loan calculator: compute the full monthly payment (P&I + MIP + tax + insurance), compare financed vs upfront UFMIP, and estimate when MIP ends. Mortgagee Letter 2023-05 rules.
FIB-4 Calculator — Fibrosis-4 Score with Age-Adjusted Interpretation
Free FIB-4 calculator: compute the Fibrosis-4 score from age, AST, ALT and platelet count (Sterling et al. 2006). Automatic age-adjusted cutoffs (1.30 / 2.00 / 2.67), unit handling, worked example and FIB-4 vs APRI comparison. Educational screening aid — not medical advice.
Fibonacci Generator — Sequence, Nth Term & Golden Ratio
Free online Fibonacci sequence generator with exact BigInt precision: generate N terms, compute the nth term with fast doubling, golden-ratio convergence, sums, parity stats, and Pisano periods. 100% client-side.
Fibonacci Retracement & Extension Calculator — Trading Levels
Calculate Fibonacci retracement (23.6%–100%) and extension (100%–423.6%) levels for stock, forex, and crypto trading. Free, 100% in-browser, with FAQ and worked examples.
Filament Spool Planner — Weight↔Length↔Cost Converter & Will-It-Finish Check
Free filament spool planner: grams↔meters↔cost converter, will-this-spool-finish-my-print checker (weigh the spool → net filament → GO/NO-GO verdict), multi-spool inventory tracker, empty-spool weight database and a 1.75/2.85mm length reference. 100% client-side, no signup.
File Checksum Verifier — Verify MD5, SHA-1, SHA-256, SHA-512 SHA3 Online (Free)
Free online file checksum verifier. Drag & drop any file to compute MD5, SHA-1, SHA-256, SHA-384, SHA-512 and SHA3-256 in one pass — compare against expected hashes or verify whole .sha256sum files. 100% client-side: your files never leave your browser.
Filing Cabinet Size Calculator: Dimensions, Capacity & Floor Load | nrtechstudio.com
Free filing cabinet size calculator: vertical vs lateral, letter vs legal dimensions, sheets per drawer, weight and floor load. 100% in-browser.
Tool - Final Calculator & Final Exam Calculator
High-precision final grade calculator and final exam score calculator. Computes the exact score needed on your final exam to achieve your target class grade.
Finance Charge Calculator — TILA Loan & Credit Card Finance Charges
Free finance charge calculator using Truth in Lending (Regulation Z) methodology: installment loan finance charge, credit-card average daily balance method, single-payment loans, and effective APR including fees.
Financial Calculator
High-performance, multi-mode financial calculator & loan calculator software for compound interest, TVM, loan amortization, ROI, and retirement planning.
Find and Replace Online Text Tool
Free online find and replace tool with regex support. Text replacer, search and replace string utility, regex find and replace, and mass find and replace text with instant live preview.
Find the Area of a Shape – Polygon & Irregular Shape Calculator
Find the area of a shape, online square feet calculator, polygon area calculator, land area calculator, equations for area of shapes, area and perimeter calculator, formula to find area, area of irregular figures calculator, calculate image, area calculator odd shape, rectangular surface area calculator, maps area calculator, area of a figure calculator, rectangular area calculation, sq area calculator, how to find the total area of a shape, area calculator with feet and inches, total area calculator, area square calculator, how to figure out the area of a shape, surface area of composite figures calculator, how to calculate the area of an object, square footage calculator irregular shape, how do you determine the area of a shape, area of compound figures calculator, area of region calculator, calculate square feet of irregular shape, how do i work out the area of a shape, area of a irregular rectangle calculator, how do i get the area of a shape.
Finnegan NAS Score Calculator — Neonatal Abstinence Scoring System | nrtechstudio.com
Free Finnegan Neonatal Abstinence Syndrome (NAS) score calculator: 21-item scoring checklist (Finnegan et al. 1975) with weights, interpretation bands
Fire Pit Size Calculator — 7 Ways to Size Your Fire Pit
Fire pit size calculator: 7 modes — guests, capacity, patio fit, brick ring, seating circle, propane BTU burn time, clearance check. Free, client-side
Firewood Stack Calculator - Cords, BTU, Weight & Seasoning Planner
Firewood stack calculator: stack to cords, face cords, species weight, BTU per cord, fuel cost vs propane and oil, log count, and seasoning planner.
Fish Mercury Calculator — Check Mercury Exposure From Fish
Free fish mercury calculator: estimate your weekly methylmercury intake from 43 fish using FDA/EPA average mercury levels, compare it to the EPA reference dose for your body weight, and see safe servi
Fish Oil Dosage for Cats Calculator — EPA+DHA by Weight, Label Decoder & Chart
Free fish oil dosage calculator for cats: enter weight + your product
Fish Weight Calculator — Length & Girth to Weight by Species (21 Species, 7 Modes)
Free fish weight calculator: estimate fish weight from length and girth with species-specific formulas (bass, trout, walleye, pike, salmon, redfish, NZ kingfish & more), length-only mode, relative weight (Wr) condition index, reverse weight-to-length, formula comparison, and a catch log. 100% client-side.
Fisher Equation Calculator — Nominal, Real & Inflation Solver
Fisher Equation Calculator: compute nominal, real, and inflation rates with the exact formula (1+i)=(1+r)(1+π), compare with the approximation, scenario table, and purchasing power calculator. Free and educational.
Fishing Hook Size Lab — Actual-Size Chart, Converter & Species Guide (Free)
Free interactive fishing hook size lab: actual-size hook renderer (1:1 on screen + printable), aught/mm/inch/gap converter, species × bait recommendation matrix, hook style guide, tippet X chart, treble & circle hook charts. 100% client-side, no signup.
Fishing Line Calculator — Spool Capacity, Braid Backing, Diameter, IPT & Trolling Depth
Free fishing line calculator suite: reel line capacity (two methods), braid-to-mono backing planner, line diameter chart (mono/braid/fluoro), mm-to-lb test converter, reel gear ratio to inches-per-turn, fly leader builder, leadcore trolling depth, line counter calibration and spooling cost estimator. 100% client-side.
Fixed Asset Turnover (FAT) Calculator — Fixed Asset Efficiency Ratio
Calculate fixed asset turnover (revenue ÷ average fixed assets / net PPE), compare with total asset turnover, compare two companies or two periods, plus interpretation and FAQ. 100% in the browser.
Fixed Deposit (FD) Calculator India — Maturity Value, Interest & Effective Yield
Free fixed deposit calculator for India: estimate FD maturity value, total interest and effective yield. Compare monthly, quarterly, half-yearly and yearly compounding, with senior-citizen rate toggle.
Flagpole Size Calculator — 7-in-1 Planner
Free flagpole size calculator with 7 modes: pole height, flag size, foundation, wind load, halyard, lighting and cost.
Flange Size Calculator — Breast Pump & ANSI Pipe Flange Sizer
Find your breast pump flange size from nipple mm (Spectra, Medela, Motif, Willow) or look up ANSI B16.5 pipe flange dimensions. Free, in-browser tool.
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Try a different keyword like "calculator", "planner", "converter" - or pick a category above.
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.