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Free online tools that just work
Hand-built calculators and converters for everyday questions. All your data stays on your device.
Why Toolify
Every Toolify tool is built around four promises:
Your data stays on your device
Calculations run in your browser. We never see your inputs — no servers, no logging.
No signup, no install
Open the tool, get the answer. Bookmarkable URLs, mobile-friendly, works offline once loaded.
Hand-checked formulas
Each calculator's math is reviewed against authoritative sources — not pulled from a random API.
17 languages, real translations
Every tool is translated with locale-specific examples and terminology — not machine-translated.
Pregnancy & Fertility Calculators
A connected set of tools for the whole journey — from tracking your fertile window to counting the weeks. Each one handles irregular cycles, multiple dating methods, and gives you real dates, not just a number.
Browse all tools →By category
Popular tools
+213 more →BMI Calculator (metric & imperial, with category)
Calculate your Body Mass Index in metric or imperial units, with category interpretation.
Length Converter (mm, cm, m, km, in, ft, yd, mi)
Convert between metric and imperial length units instantly. Includes mm, cm, m, km, inches, feet, yards, and miles.
Age Calculator (years, months, days, weeks, hours)
Calculate exact age in years, months, days, weeks, and hours from any birth date to any target date.
Percentage Calculator (% of, what %, % change)
Three percentage calculators in one: 'X% of Y', 'X is what % of Y', and percentage change between two values.
Tip Calculator (with bill split for groups)
Calculate tip and split a restaurant bill across any number of people. Quick presets for common tip percentages.
Temperature Converter (Celsius, Fahrenheit, Kelvin, Rankine)
Convert between Celsius, Fahrenheit, Kelvin, and Rankine. All four scales update at once.
Password Generator (cryptographically secure, with strength meter)
Generate strong random passwords using your browser's secure crypto API. Configurable length, character sets, and ambiguity filter.
Word Counter (with reading and speaking time)
Count words, characters, sentences, paragraphs, plus estimated reading and speaking time. Handles CJK languages correctly.
Free Countdown Timer 2026 — Days, Hours, Minutes, Seconds (No Signup)
Free online countdown timer. Pick any date & time, see days/hours/minutes/seconds tick down live. Add event title, watch elapsed time after target — no signup.
Recommended services
DisclosureAI prompts
Browse all tools →claude · chatgpt
Senior code reviewer prompt — finds bugs, perf issues, edge cases
A reusable prompt for Claude/ChatGPT/Cursor that turns the model into a senior reviewer focused on correctness, performance, and edge cases — not nitpicks.
chatgpt · claude
Email rewriter prompt — clear, concise, tone-controlled
Rewrite any email draft to be clearer and shorter without losing the message. Pick a tone (warm / neutral / firm) and a length target.
claude · chatgpt
Blog post outline prompt — H2/H3 structure with intent and word counts
Generate a tight, search-friendly outline for a blog post: H2/H3 hierarchy, intent per section, target word counts, and the questions each section answers.
midjourney
Midjourney portrait prompt — controllable face, lighting, lens, mood
A modular Midjourney prompt template for portraits with explicit control over subject, framing, lighting, lens, mood, and style. Avoids the generic 'AI portrait' look.
claude · perplexity
Research summary prompt — extract claims, evidence, and contradictions
Turn long PDFs, papers, or reports into a structured summary that distinguishes claims from evidence, surfaces contradictions, and quotes source pages so you can verify.
chatgpt · claude
Meeting prep prompt — agenda, decisions, async-or-meeting check
Generate a sharp meeting agenda from rough notes, including time budget, decisions to be made, and a 'should this be async' check at the top.
claude · chatgpt
Ad copy variants prompt — 6 angles, 3 lengths, no filler
Generate 6 distinct ad copy variants for the same offer — different persuasive angles (problem, outcome, identity, social proof, scarcity, comparison), each in three ad-platform-ready lengths.
claude · chatgpt
User interview script prompt — past behavior, no leading questions
Generate a 30-minute user interview script with open questions, follow-ups for each, and strict no-leading rules. Modeled on Mom Test principles.
All tools (A–Z)
Math & Numbers56 tools
- Aspect Ratio Calculator (preserve ratio when resizing)
- Average Speed Calculator (km/h)
- Board Foot Calculator - Lumber BF Measurement
- Box Volume Calculator (cm to liters)
- Circle Calculator — Area, Circumference, Diameter, Radius
- Combination Calculator (nCr) — Choose r from n
- Concrete Calculator – Cubic Yards & Meters
- Cone Volume Calculator (cm³ and Liters)
- Cylinder volume calculator (cm³ and liters)
- Density Calculator (Mass / Volume)
- Dice Roller (d4 to d100, with modifier and history)
- Exponent Calculator - Raise Base to a Power
- Factorial / Permutations / Combinations Calculator
- Fibonacci Calculator — Nth Term and Sequence
- Fraction Calculator (add, subtract, multiply, divide)
- GCD & LCM Calculator (with prime factorizations)
- Geometric Shapes Calculator — Volume & Surface Area
- GPA Calculator (4.0 scale, weighted by credits)
- Grade Calculator — Weighted Average & Letter Grade
- Gravel Calculator - Estimate Yards & Tons
- Half-life Calculator — Exponential Decay
- Kinetic Energy Calculator (KE = ½mv²)
- Logarithm calculator - compute log base b of any value
- Math Expression Calculator — evaluate any formula online
- Matrix Calculator — Add, Multiply, Determinant
- Midpoint Calculator – Midpoint of Two Points
- Modulo Calculator - Remainder of a mod b
- Molarity Calculator (mol/L to moles)
- Number Base Converter (binary, octal, decimal, hex)
- Number Sequence Generator — Arithmetic, Geometric, Fibonacci & More
- Number to Words Converter — English Word Form
- Ohm's Law Calculator — Voltage, Current, Resistance & Power
- Paint Calculator (gallons or liters from room size)
- Percent Error Calculator — Experimental vs Theoretical
- Percentage Calculator (% of, what %, % change)
- Percentage Change Calculator — Increase & Decrease
- Permutation Calculator (nPr)
- Pixel Density Calculator — PPI for Any Screen
- Prime Factorization Calculator — Find Prime Factors Instantly
- Prime Number Checker (with factorization)
- Probability Calculator — Basic, Permutations, Combinations, Dice
- Proportion Calculator: Solve a / b = c / x
- Pythagorean Theorem Calculator — Find Any Side
- Quadratic Equation Solver (ax² + bx + c = 0)
- Random Number Generator (cryptographically secure, unique mode)
- Ratio Simplifier — Reduce a:b to Lowest Terms
- Scientific Notation Converter (decimal ↔ scientific)
- Significant Figures Calculator — Count & Round Sig Figs
- Slope Calculator – Two Points to Slope & Angle
- Sphere Volume Calculator (4/3·π·r³)
- Square Footage Calculator – Area in ft²
- Square Root Calculator (√ and ∛)
- Statistics Calculator (mean, median, std dev, quartiles)
- Tile Calculator - Tiles Needed for Any Room
- Triangle Calculator (right angle, SSS, SAS)
- Z-Score Calculator – Standard Score
Finance53 tools
- Annuity Payout Calculator (fixed-period)
- Bill Split Calculator — Split Bills & Tip Evenly
- Break-Even Calculator — Units, Revenue & Contribution Margin
- CAGR Calculator (Compound Annual Growth Rate)
- Car Loan Calculator (monthly payment + total interest)
- Compound Interest Calculator (with monthly contributions)
- Cost of Living Comparison (city to city, equivalent salary)
- Cost per Use Calculator
- Credit Card Validator (Luhn check + brand detection)
- Credit Utilization Calculator (per-card and overall)
- Crypto Profit Calculator (with exchange fees)
- Debt Payoff Calculator — Pay Off Date & Interest
- Debt-to-Income (DTI) Ratio Calculator
- Discount Calculator (with optional sales tax)
- Down Payment Calculator for Home Buyers
- Effective Annual Rate Calculator (EAR / APY)
- Electricity Cost Calculator — kWh & Bill Estimator
- Emergency Fund Calculator (3-12 months of expenses)
- Expense Ratio Calculator — True Cost of Investment Fees
- FIRE Number Calculator — Financial Independence Retire Early
- Free Unit Price Calculator 2026 — Cost per Gram, Ounce or Count
- Fuel Cost Calculator (trip cost + per-person split)
- Future Value Calculator - Compound Interest FV
- House Affordability Calculator — How Much Can You Afford?
- Income Tax Bracket Calculator (JP / US)
- Inflation Calculator (purchasing power over time)
- Japan Price Comparison — Rakuten Ichiba
- Lease vs Buy Calculator (car, total cost over hold period)
- Life Insurance Needs Calculator (DIME formula)
- Loan Amortization Schedule (full or yearly)
- Loan Calculator (monthly payment, interest, total cost)
- Markup Calculator (cost to sell price + margin)
- Meeting Cost Calculator — Real Cost of Meetings
- Mortgage Calculator (PITI: principal, interest, tax, insurance)
- Mortgage Refinance Calculator (break-even + lifetime savings)
- Net Worth Calculator (assets minus liabilities)
- Overtime Pay Calculator
- Paycheck Calculator — 2024 US Federal Take-Home Pay
- Present Value Calculator (PV of Future Money)
- Profit Margin Calculator – Margin & Markup
- Retirement Calculator (compound projection + inflation-adjusted)
- ROAS Calculator (Return on Ad Spend)
- ROI Calculator (Return on Investment + Annualized)
- Rule of 72 Calculator (doubling time / required rate)
- Salary Converter (hourly, daily, weekly, monthly, annual)
- Sales Commission Calculator - Commission & Net Pay
- Sales Tax / VAT Calculator (add tax or extract from total)
- Savings Goal Calculator (time to reach target)
- Simple Interest Calculator (I = P × r × t)
- SIP Calculator — Mutual Fund Maturity Value
- Stock Profit Calculator (with dividends + taxes)
- Tip Calculator (with bill split for groups)
- VAT / Sales Tax Calculator (international rates)
Text & Code40 tools
- ASCII Table — Decimal, Hex, Binary, Octal & Character Chart
- Base64 Encoder / Decoder (UTF-8 and URL-safe)
- Caesar Cipher Encoder / Decoder (with ROT13)
- Case Converter (camel, snake, kebab, Title, etc.)
- Character Frequency Analyzer (letters, all chars, or words)
- CSV ↔ JSON Converter (RFC 4180 compliant)
- Device Info Checker (browser, OS, hardware, network)
- Duplicate Line Remover — Clean Text Lists Instantly
- Email Validator (syntax + common typo detection)
- Find and Replace Text (literal or regex, with options)
- Free Roman Numeral Converter 2026 — Numbers 1–3999 (Both Directions)
- Hash Generator (SHA-1, SHA-256, SHA-384, SHA-512)
- HTML Entity Encoder & Decoder — Named, Numeric & Hex
- HTML to Markdown Converter
- IPv4 Subnet Calculator (CIDR, mask, hosts)
- JSON Formatter & Minifier (validates and pretty-prints)
- JSON to YAML Converter — Bidirectional
- JWT Decoder (header, payload, signature, expiry)
- Keyboard Key Code Finder — keyCode, code, key Properties
- Lorem Ipsum Generator (paragraphs, sentences, words)
- Markdown to HTML Converter (CommonMark subset)
- Morse Code Translator — Text to Morse and Back
- Password Generator (cryptographically secure, with strength meter)
- Password Strength Tester (entropy + crack time)
- QR Code Generator — Free, No Login Required
- Reading Level Checker — Flesch Score & Grade Level
- Reading Time Calculator – Words to Minutes
- Regex Tester (live matches, groups, replace)
- Resistor Color Code Calculator — Decode and Encode Band Colors
- Reverse Text Generator — Flip Characters, Words, or Lines
- Text Diff Tool (line-level comparison, color-coded)
- Text Sorter — Sort Lines Online (A–Z, Z–A, Deduplicate)
- Text to Binary Converter — Encode & Decode Binary Code
- Typing Speed Test — WPM & Accuracy
- Unix File Permissions Calculator (chmod)
- URL Encoder / Decoder (percent-encoding, UTF-8 safe)
- URL Slug Generator (SEO-friendly URLs)
- UUID Generator (v4 random, v7 time-ordered)
- Word Counter (with reading and speaking time)
- WPM Typing Speed Test 2026 — Free Words Per Minute Counter
Health & Fitness32 tools
- A1C to Average Glucose Calculator (eAG)
- Blood Pressure Checker — AHA 2017 Categories Explained
- BMI Calculator (metric & imperial, with category)
- BMR Calculator (Mifflin, Harris-Benedict, Katch-McArdle)
- Body Fat Calculator (US Navy Method)
- Body Surface Area Calculator (BSA)
- Calorie Calculator (BMR & TDEE, Mifflin-St Jeor)
- Calorie Deficit Calculator — TDEE & Weight Loss
- Cat Age Calculator - Cat Years to Human Years
- Conception Date Calculator — from due date or birth date
- Dog Age Calculator — Convert Dog Years to Human Years
- Due Date Calculator — LMP, IVF, ultrasound or conception
- Exercise Calorie Calculator — MET-based calories burned
- hCG Calculator — doubling time & rise from two values
- Ideal Weight Calculator (Devine, Robinson, Miller, Hamwi)
- Macro Calculator (P/F/C grams from TDEE and goal)
- Maximum Heart Rate Calculator (by Age)
- One-Rep Max Calculator (5 formulas + percent table)
- Ovulation Calculator — fertile window for irregular cycles
- Period Calculator — next 6 periods & cycle phase
- Ponderal Index Calculator (kg/m³)
- Pregnancy Week Calculator — weeks + prenatal schedule
- Pregnancy Weight Gain Calculator — by pre-pregnancy BMI
- Protein Intake Calculator – Daily Grams
- Running Pace Calculator (time, pace, speed)
- Sleep Calculator — Find Your Ideal Bedtime or Wake-Up Time
- Steps to Distance Calculator — km, Miles, Calories & Time
- Target Heart Rate Calculator (5 training zones)
- Waist-to-height ratio calculator
- Waist-to-Hip Ratio Calculator (cardiovascular risk)
- Water Intake Calculator (daily target by weight)
- Weight Loss Calculator (timeline + target date)
Unit Converters18 tools
- Angle Converter (degrees, radians, gradians, turns)
- Area Converter (m², ft², acre, hectare, tsubo)
- Coffee Ratio Calculator – Water to Coffee
- Cooking Unit Converter — Cups, Tbsp, Tsp, ml, g, oz
- CSS Unit Converter — px, rem, em, pt, % Online
- Currency Converter — 31 Currencies, Instant Results
- Data Size Converter (B, KB, MB, GB, TB — SI and IEC)
- Fuel Economy Converter (mpg US/UK, km/L, L/100km)
- Heat Index Calculator — Feels Like Temperature & Humidity
- Length Converter (mm, cm, m, km, in, ft, yd, mi)
- Power Unit Converter (W, kW, hp, BTU/h)
- Pressure Converter (Pa, bar, psi, atm, mmHg)
- Speed Converter (km/h, mph, m/s, knot, Mach)
- Temperature Converter (Celsius, Fahrenheit, Kelvin, Rankine)
- Time Unit Converter (ms, s, min, h, days, weeks, months, years)
- Volume Converter (mL, L, gal, fl oz, cup, tsp)
- Weight Converter (kg, g, t, lb, oz, stone, mg)
- Wind Chill Calculator — Feels Like Temperature
Date & Time15 tools
- Age Calculator (years, months, days, weeks, hours)
- Age Difference Calculator (between two people)
- Cron Expression Tester (preview next 5 runs)
- Date Calculator (add/subtract days, or difference between dates)
- Day of the Week Calculator — Find Any Weekday
- Free Countdown Timer 2026 — Days, Hours, Minutes, Seconds (No Signup)
- Hours Calculator — Add, Subtract & Convert Time
- ISO Week Number Calculator (week-of-year)
- Leap Year Checker (with rule explanation)
- Moon Phase Calculator (any date, illumination %)
- Pomodoro Timer (25/5/15 with audio cue)
- Stopwatch (millisecond precision, lap times)
- Timezone Converter (compare time across multiple zones)
- Unix Timestamp Converter (sec, ms, ISO, local)
- Workdays Calculator (skip weekends + holidays)
Color & Design8 tools
- Color Blindness Simulator — See Colors as Others Do
- Color Converter (HEX, RGB, HSL — instant)
- Color Palette Generator (5 schemes from one base)
- Color Shades Generator — Tailwind-Style Tints & Shades
- Contrast Checker (WCAG AA / AAA grades)
- CSS Box Shadow Generator (with live preview)
- CSS Color Name Finder — Nearest Named Color from Hex
- CSS Gradient Generator (linear, radial, conic)