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BlackCloudTools
24 calculators & converters. Always free.
Math
9 toolsAspect Ratio Calculator
Simplify a width:height ratio (e.g. 1920x1080 to 16:9) or solve for a missing dimension from a target ratio. Free tool for video, photo, and design.
ratio = width / gcd(width, height) : height / gcd(width, height)🔧Depth of Field & Hyperfocal Distance Calculator
Calculate hyperfocal distance and the near/far limits of acceptable sharpness from focal length, aperture, subject distance, and sensor format. Free, instant.
H = f² / (N·c) + f📐Pythagorean Theorem Calculator
Calculate any side of a right triangle using the Pythagorean theorem. Solve for hypotenuse, base, or height instantly.
a² + b² = c²📊Mean Median Mode Calculator
Calculate mean, median, mode, range, and standard deviation from any set of numbers. Free statistics calculator.
Mean = Σx / n√Square Root Calculator
Calculate square roots, cube roots, and nth roots. Shows simplified radical form (e.g. 6√2) and detects perfect squares.
√n = coefficient√radicand🔷Surface Area Calculator
Calculate surface area of 6 shapes: sphere, cube, cylinder, cone, rectangular prism, and square pyramid. Step-by-step solutions.
Sphere: 4πr²½Decimal to Fraction Converter
Convert any decimal to a simplified fraction in lowest terms. Shows mixed number, GCD steps, and fraction check.
n / 10^(decimal places) → simplify by GCD🎂Age Calculator
Calculate exact age between two dates. Shows years, months, days, total weeks, hours, and next birthday countdown.
targetDate − birthDate🔧Sudoku Solver
Solve any 9x9 Sudoku puzzle instantly in your browser. Type digits into the grid or paste a puzzle string, plus a built-in validator to check for conflicts.
Backtracking search: try 1-9 per empty cell, recurse, undo on conflictConverters
9 toolsWeight Converter
Convert weight between kilograms, pounds, ounces, grams, milligrams, metric tons, and stone. NIST-exact conversion factors.
Convert between metric and imperial units🌡️Temperature Converter
Convert temperature between Celsius, Fahrenheit, Kelvin, and Rankine. Instant, accurate temperature unit converter.
°F = (°C × 9/5) + 32📐Length Converter
Convert length between 9 units: millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, and nautical miles. NIST-exact.
All units → meters → target unit🚀Speed Converter
Convert speed between mph, km/h, m/s, knots, and feet per second. Instant speed unit converter with all common units.
All units → m/s → target unit🧪Volume Converter
Convert volume between liters, milliliters, gallons, quarts, pints, cups, fluid ounces, and cubic meters. Metric and imperial.
All units → liters → target unit⛽Fuel Cost & Gas Mileage Calculator
Calculate gas mileage (MPG, km/L, L/100km) from your trip distance and fuel used, or estimate total fuel cost from distance, efficiency, and fuel price.
MPG = distance ÷ fuel used; Cost = (distance ÷ MPG) × price per gallon🍳Recipe Converter & Scaler
Scale a recipe up or down for any number of servings, or convert common baking ingredients between cups, tablespoons, teaspoons, grams, and ounces.
scaled amount = original amount × (target servings ÷ original servings)💾Digital Storage Unit Converter
Convert between digital storage units — bits, bytes, KB/MB/GB/TB/PB (decimal) and KiB/MiB/GiB/TiB/PiB (binary). See why your 1TB drive shows as 931GB.
bytes = value × factor(fromUnit); result = bytes ÷ factor(toUnit) [decimal: 1000ⁿ, binary: 1024ⁿ]⏱️Download & Upload Time Calculator
Estimate how long a file transfer will take from file size and connection speed, or back-solve the speed needed to hit a target time. Free, instant, no upload.
time (s) = (file size in bytes × 8) ÷ speed in bits per secondFinance
15 toolsSimple Interest Calculator
Calculate simple interest on loans and investments. Shows total amount, daily, and monthly interest breakdown.
SI = (P × R × T) / 100📈Compound Interest Calculator
Calculate compound interest with all compounding frequencies. Includes contributions, APY, and year-by-year growth table.
A = P(1 + r/n)^(nt)🔧APR to APY Calculator
Convert a nominal APR to its effective APY (or back) for any compounding frequency — daily, monthly, quarterly, semi-annually, annually, or continuous. Free, instant.
APY = (1 + APR/n)^n − 1🔧Rule of 72 Calculator
See how many years it takes to double your money at a given rate using the Rule of 72 shortcut, plus the exact compound-interest doubling time. Free, instant, reverse mode included.
Years ≈ 72 / Rate🔧Rental Yield Calculator
Calculate gross and net rental yield from a property's purchase price, rent, and operating costs. Includes price-to-rent ratio and payback period. Free, instant.
Gross Yield = (Annual Rent / Price) × 100％Percentage Calculator
Calculate percentages in 4 modes: X% of Y, X is what % of Y, percentage change, and percentage difference.
(X / Y) × 100🏷️Discount Calculator
Calculate sale price after discount. Find discount amount, final price, and savings instantly. Supports any percentage.
Final = Original × (1 - Discount%/100)🛒Unit Price Calculator
Calculate price per oz, lb, g, kg, liter, or item and compare up to 4 products side-by-side to find the best value. Free grocery price comparison tool.
Unit Price = Total Price ÷ Quantity🍽️Tip Calculator
Calculate tip amount and split the bill among multiple people. Supports custom tip percentages and any number of guests.
Tip = Bill × Tip% / 100🔧Restaurant Tip Pool & Tip-Out Calculator
Split a pooled tip total among staff by hours worked or shift points, or calculate server tip-out percentages owed to bartenders, bussers, and hosts.
Employee share = (weight ÷ total weight) × pool total; Tip-out = base amount × recipient %🔧Payment Processing Fee Calculator
Calculate the fee PayPal, Stripe, Square, or a custom processor deducts from a payment, and your net payout. Reverse mode solves what to charge to net a target amount.
Fee = Gross × Rate% + Fixed Fee; Net = Gross − Fee; Reverse: Gross = (Net + Fixed Fee) ÷ (1 − Rate%)💼Gratuity Calculator
Calculate gratuity payout under the Payment of Gratuity Act 1972. Shows tax exemption up to ₹20 lakh and eligibility check.
(Salary × 15 × Years) / 26🏦Recurring Deposit Calculator
Calculate RD maturity amount with quarterly compounding. Month-by-month breakdown showing exact interest earned each quarter.
Quarterly compounding per RBI guidelines🎯Savings Goal Calculator
Find out how much you need to save each month to reach a savings goal, or how long it will take at a fixed contribution. Includes interest. Free, instant.
FV = PV(1 + r)ⁿ + PMT × [((1 + r)ⁿ − 1) / r]🔧Credit Card Validator
Check if a card number passes the Luhn checksum, identify its network (Visa, Mastercard, Amex, Discover & more), and generate Luhn-valid test numbers for QA.
Luhn: double every 2nd digit from the right, subtract 9 if > 9, sum must be divisible by 10Health
6 toolsBMI Calculator
Calculate your BMI (Body Mass Index) with our free online tool. Includes WHO categories, health recommendations, and metric/imperial support.
BMI = weight (kg) / height (m)²💧Water Intake Calculator
Calculate daily water intake based on weight, activity level, exercise, and climate. Shows glasses and bottles needed.
30–44 ml per kg by activity level💪Protein Calculator
Calculate daily protein needs based on body weight and activity level. Based on WHO RDA 0.8 g/kg up to 2.2 g/kg for bodybuilders.
Protein (g) = weight (kg) × factor📏Waist to Hip Ratio Calculator
Calculate your waist-to-hip ratio (WHR) and check cardiovascular risk using WHO standards. Supports cm and inches.
WHR = waist ÷ hip❤️Target Heart Rate Zone Calculator
Calculate your target heart rate training zones from age and resting heart rate. Uses max HR (220-age) and the Karvonen formula for precise cardio zones.
Max HR = 220 − age; Target HR (Karvonen) = ((Max HR − Resting HR) × %Intensity) + Resting HR🔧Steps to Distance (Miles/KM) Calculator
Convert your step count into walking or running distance in miles and km, or find how many steps a target distance takes. Based on height and pace.
Step length = height × pace factor; Distance = steps × step lengthText
12 toolsCharacter Counter
Count characters, words, lines, spaces, and paragraphs in real time. Includes social media character limits for Twitter, Instagram, and LinkedIn.
Text Case Converter
Convert text to camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, Title Case, Sentence case, UPPER, and lower. One-click copy.
Text List Sorter & Duplicate Remover
Sort a text list A-Z or Z-A, remove duplicate lines, strip blank lines, reverse order, or shuffle randomly. Free, instant, and 100% in your browser.
Word Cloud Generator
Turn any text into a downloadable word cloud. Paste text or upload a .txt file, filter stop words, and get a PNG image — free, instant, 100% in your browser.
Readability Score Checker
Paste your text to instantly get Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog, Coleman-Liau, and SMOG readability scores. Free, no sign up, 100% in your browser.
Flesch Reading Ease = 206.835 − 1.015×(words/sentences) − 84.6×(syllables/words)🔧Syllable Counter
Paste a word, line, or poem to instantly see syllables per word and per line, with running totals and automatic haiku (5-7-5) detection. Free, no sign up, 100% in your browser.
syllables per word ≈ vowel-group count with silent-e and "-le" ending exception rules🔧NATO Phonetic Alphabet Translator
Convert text to NATO/ICAO phonetic alphabet spelling (Alpha, Bravo, Charlie...) or decode code words back to plain text. Free, instant, 100% in your browser.
Each letter/digit → its NATO/ICAO code word (A → Alpha, 1 → One); decode reverses the lookup🔧Text to Braille Translator
Convert English text to Grade 1 Braille Unicode cells, or decode Braille back to plain text. Free, instant, 100% in your browser — no sign up.
Each letter/digit/punctuation → its Grade 1 Braille Unicode cell (U+2800–U+28FF); decode reverses the lookup🔧Zalgo / Glitch Text Generator
Turn plain text into corrupted "Zalgo" glitch text with a mild-to-chaotic intensity slider, or clean cursed text back to normal. Free, instant, in your browser.
Insert random Unicode combining marks (U+0300–U+036F) above/below/through each character; clean mode strips them🔧Find & Replace Text Tool
Find and replace text instantly with case-sensitive, whole-word, and regex matching plus a live match counter. Free, bulk find and replace, 100% in your browser.
output = text.replace(new RegExp(pattern, flags), replacement) — pattern is escaped (plain mode) or user regex, flags = g?/i? based on replace-all and case-sensitive toggles🔧Image to Text (OCR) Converter
Extract editable text from a photo, screenshot, or scanned document entirely in your browser. Free OCR in 12 languages, no upload, no sign-up.
Text Encryptor & Decryptor (AES)
Encrypt or decrypt text with a passphrase using AES-256-GCM, entirely in your browser. Free, instant, no sign-up, and your text never leaves your device.
AES-256-GCM with a PBKDF2-derived key (SHA-256, 250,000 iterations)Image
11 toolsImage Format Converter
Convert images between PNG, JPG, WebP, AVIF, and BMP for free, right in your browser. No upload, no sign-up, no watermark.
HEIC to JPG/PNG Converter
Convert iPhone HEIC/HEIF photos to JPG or PNG, free and instantly in your browser. No upload, no sign-up, no watermark.
Image Compressor
Compress JPG, PNG, and WebP images to a target file size in KB or MB, free and instantly in your browser. No upload required.
Image Resizer
Resize images to exact pixel dimensions or common presets like passport photo, LinkedIn, Instagram, and YouTube thumbnail. Free, in-browser.
SVG to PNG Converter
Convert SVG vector images to PNG or JPG at any resolution, free and instantly in your browser. No server upload.
PNG to SVG Converter (Image Vectorizer)
Convert PNG or JPG images to scalable SVG vector graphics, free and instantly in your browser. No upload, no sign-up — ideal for logos, icons, and line art.
Favicon Generator
Generate a multi-size favicon.ico file from any image or logo, free and instantly in your browser. Includes 16, 32, 48, 64, 128, and 256px sizes.
Image to Base64 Converter
Convert images to Base64 strings for embedding in CSS or HTML, or decode Base64 back into a downloadable image. Free, instant, in-browser.
Color Palette Extractor
Extract the dominant colors and a matching palette from any image, with hex and RGB values. Free tool for designers, runs entirely in-browser.
Duplicate Image Finder
Scan a batch of photos for exact and near-duplicate images and pick which copies to keep. Free, no upload — everything runs in your browser.
Photo EXIF Data Viewer & Remover
View a JPEG photo’s EXIF metadata (camera, settings, GPS location) and strip it in one click before sharing. Free, private, runs entirely in your browser.
Data
8 toolsQR Code Generator
Generate free QR codes for URLs, plain text, WiFi networks, and contact cards (vCard). Download as PNG, no sign-up, no expiry.
CSV to JSON Converter
Convert CSV to JSON or JSON to CSV instantly in your browser. Handles quoted fields, commas, and headers correctly. Free, no upload.
XLSX to CSV Converter
Convert Excel (XLSX) spreadsheets to CSV or CSV to XLSX, free and instantly in your browser. Supports multi-sheet workbooks. No upload.
JSON to YAML Converter
Convert JSON to YAML or YAML to JSON instantly in your browser. Supports nested config, multi-document YAML, and indentation control. No upload.
ISBN Validator & Format Converter
Check if an ISBN-10 or ISBN-13 is valid and convert between formats instantly in your browser. Free checksum validator for books, no lookup required.
ISBN-10: sum(digit×weight 10..2) mod 11 = 0 | ISBN-13: sum(digit×weight 1,3,1,3...) mod 10 = 0🔧UTM Campaign URL Builder
Build UTM-tagged campaign URLs for Google Analytics. Add utm_source, utm_medium, utm_campaign, utm_term & utm_content with live preview, free and instant.
url = baseUrl + "?utm_source="+source+"&utm_medium="+medium+"&utm_campaign="+campaign[+"&utm_term="+term][+"&utm_content="+content]🔧CSS Cubic-Bezier Easing Curve Generator
Drag control points on a live curve to design a CSS cubic-bezier() timing function, preview the animation, and copy the ready-to-use CSS. Free, no upload.
B(t) = 3(1-t)²t·P1 + 3(1-t)t²·P2 + t³, with P0=(0,0), P3=(1,1)🔧CSS Clip-Path Generator
Drag points on a live preview to build a CSS clip-path shape (polygon, circle, ellipse, inset), then copy the ready-to-use CSS. Free, no upload.
clip-path: polygon(x1% y1%, x2% y2%, ...) | circle(r% at cx% cy%) | ellipse(rx% ry% at cx% cy%) | inset(top% right% bottom% left% round r%)PDF Merge
Merge multiple PDF files into a single document, free and instantly in your browser. Reorder files before merging. No upload required.
PDF Split
Split a PDF into multiple files by page range, free and instantly in your browser. No upload, no sign-up.
PDF Rotate & Reorder
Rotate and reorder PDF pages by dragging them into place, free and instantly in your browser. No upload, no sign-up.
Images to PDF
Combine multiple images into a single PDF file, free and instantly in your browser. Supports JPG, PNG, WebP, and BMP. No upload required.
PDF to Image Converter
Convert every page of a PDF into a PNG or JPG image, free and instantly in your browser. No upload, no sign-up, no watermark.
PDF Compressor
Reduce PDF file size for free, right in your browser. Best for scanned or image-heavy PDFs. No upload, no sign-up.
PDF Watermark Adder
Add a text or image watermark to a PDF for free, right in your browser. Control opacity, rotation, position, and pages. No upload, no sign-up.
Audio/Video
9 toolsVideo to Audio Converter
Extract the audio track from any video as MP3, WAV, AAC, or OGG, free and instantly in your browser. No upload, no sign-up.
Audio Format Converter
Convert audio files between MP3, WAV, and OGG, free and instantly in your browser. No upload, no sign-up.
Video Trimmer
Trim or cut a video to a specific start and end time, free and instantly in your browser. No upload, no sign-up, no watermark.
Audio Trimmer & Cutter
Trim or cut an audio file to a specific start and end time, free and instantly in your browser. MP3, WAV, OGG, M4A supported. No upload, no sign-up.
Audio Speed & Pitch Changer
Change an audio file's playback speed and pitch independently, free and instantly in your browser. Slow down or speed up audio without changing pitch. No upload, no sign-up.
Video to GIF Converter
Convert a video clip to a high-quality animated GIF, free and instantly in your browser. No upload, no sign-up, no watermark.
Video & Audio Bitrate File Size Calculator
Calculate the file size an export will produce from bitrate and duration, or back-solve the bitrate needed to hit a target file size. Free, instant, no upload.
File size (bytes) = (bitrate × duration in seconds) ÷ 8🔧Video Frame Rate & Timecode Calculator
Convert between frame count, SMPTE timecode (HH:MM:SS:FF), and duration for any frame rate, with drop-frame and non-drop-frame support for 29.97/59.94fps NTSC. Free, instant.
frames = round(seconds × fps); timecode = HH:MM:SS:FF from frame count🔧Tap Tempo & Delay Time (BPM) Calculator
Tap along to a beat to find its BPM, or enter a tempo to instantly get delay, reverb, and LFO times in milliseconds for every note subdivision. Free, instant.
msPerBeat = 60000 ÷ BPM; subdivision ms = msPerBeat × note ratio × (straight | dotted ×1.5 | triplet ×2/3)