All Tools

Explore math, physics and chemistry calculators alongside image, PDF and text utilities. Browse by subject or search by keyword.

Mathematics & Statistics

Quadratic Equation

Solve ax² + bx + c = 0 with real or complex roots, the discriminant and substitution into the quadratic formula.

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Mathematics & Statistics

Statistics Calculator

Paste numbers to get count, sum, mean, median, min, max and standard deviation at once. Handles newline, comma and space separators.

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Mathematics & Statistics

Fraction Calculator

Add, subtract, multiply and divide fractions with exact results. See the reduced answer plus mixed-number and decimal forms, with the working shown.

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Mathematics & Statistics

Prime Factorization

Factor any positive integer into primes. See the product form, exponent form (e.g. 2³×3²) and the number of divisors at once.

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Mathematics & Statistics

Permutation & Combination Calculator

Compute nCr, nPr and n! with exact big-integer arithmetic. Large results such as lottery odds never overflow, and every calculation shows its working step by step.

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Mathematics & Statistics

Trigonometry Calculator

Enter an angle to get sin, cos and tan at once. Special angles like 30°, 45° and 60° are shown as exact values (1/2, √3/2), with degree and radian support, pi expressions such as pi/6, plus the quadrant signs and the reference-angle working.

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Mathematics & Statistics

Logarithm Calculator

Compute logarithms in any base, like log₂(8). One-tap bases for 2, 10 and e, with the change-of-base working (ln x ÷ ln b) and a check that bʸ returns x. Common and natural logarithm notes included.

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Mathematics & Statistics

Sequence & Series Calculator

Get the n-th term and the sum of arithmetic or geometric sequences from the first term, difference (ratio) and count — computed exactly with BigInt. The substituted general-term and sum formulas are shown, and huge geometric results stay error-free.

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Mathematics & Statistics

Vector Calculator (Dot Product)

Compute the dot product, magnitudes and the angle between 2D or 3D vectors with fully substituted working. Includes the cosθ = (a·b) ÷ (|a||b|) step and perpendicular detection via a·b = 0 — handy for math and physics.

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Mathematics & Statistics

Matrix Determinant & Inverse

Compute the determinant and inverse of 2×2 and 3×3 matrices with cofactor-expansion working. Detects singular matrices (det = 0) and verifies the inverse — useful for math B and linear algebra students.

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Physics

Constant Acceleration

Calculate velocity and displacement from initial velocity, constant acceleration and time, with unit conversion and worked steps.

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Physics

Significant Figures Calculator

Count significant figures, round to a chosen precision, and apply the multiplication/division or addition/subtraction rules. Switch between half-up and JIS Z 8401 half-even rounding; scientific notation is shown alongside.

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Physics

Equivalent Resistance Calculator

Compute the equivalent resistance of resistors in series or parallel with fully substituted working. Handles 2 to 4 resistors and cross-checks the two-resistor parallel shortcut R₁R₂ ÷ (R₁ + R₂) — handy for physics circuits.

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Chemistry

Moles & Molarity

Calculate molarity from moles and solution volume, or convert mass to moles with a supplied molar mass. View results in mol/L and mmol/L.

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Chemistry

Dilution Calculator

Find the required stock volume from stock concentration, target concentration and final solution volume using C₁V₁ = C₂V₂.

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Chemistry

pH Calculator

Compute pH from hydrogen ion concentration or the reverse, in both directions. Accepts e-notation like 1e-7 and shows the substituted pH = −log₁₀[H⁺] working plus an acidic / neutral / basic classification based on 25 °C water.

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Data Conversion & Generation

Hex & Text Converter

Convert Hex bytes and UTF-8 text in your browser. Inspect byte counts, Japanese characters and invalid UTF-8 without uploading data.

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Data Conversion & Generation

JSON Formatter

Format, minify, validate and unescape JSON right in your browser.

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Data Conversion & Generation

Base64 Converter

Encode or decode text, images and files to and from Base64.

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Data Conversion & Generation

UUID Generator

Generate UUIDs (v4) in bulk for free. Handy for API development and test data.

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Data Conversion & Generation

CSV to JSON Converter

Convert between CSV and JSON. Supports comma, tab and semicolon delimiters with optional header rows.

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Data Conversion & Generation

Number Base Converter

Convert between binary, octal, decimal and hexadecimal. Handles arbitrarily large integers with exact precision and readable digit grouping.

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Data Conversion & Generation

URL Encoder / Decoder

Encode text into URL (percent) encoding and decode it back. Handy for building Japanese URLs and query parameters or inspecting encoded strings.

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Data Conversion & Generation

Data Size Converter

Convert between bit, byte, KB, MB, GB, TB and PB. Switch between binary (1024) and decimal (1000) conventions to answer "how many MB in 1GB?" accurately.

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Text Editing & Search

Text Converter

Convert case (lowercase, uppercase, title case) and clean up text: remove blank lines, trim spaces, and count characters, lines and UTF-8 bytes.

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Text Editing & Search

Kanji Number Converter

Convert between Arabic numerals and Kanji numerals (一, 十, 百, 千, 万).

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Text Editing & Search

Full-width / Half-width Converter

Convert between full-width and half-width characters. Handles letters, digits, symbols, spaces, and katakana with voiced marks.

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Text Editing & Search

Roman Numeral Converter

Convert between Arabic numerals and Roman numerals (I, V, X and more). Supports 1-3999 and tolerates non-standard forms like clock-face IIII.

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Text Editing & Search

Regex Tester

Test a regex pattern against any text and instantly see matches highlighted. Supports flags (g/i/m/s/u) and match details.

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Text Editing & Search

Text Diff / Compare

Compare two texts in your browser. See line-by-line additions and deletions side by side, with instant stats on what changed.

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Ciphers, Hashes & Passwords

Caesar Cipher & ROT13

Explore Caesar shifts and ROT13 with case-preserving letter conversion. Learn substitution with worked examples, entirely in your browser.

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Ciphers, Hashes & Passwords

XOR Calculator

Calculate XOR using Hex or UTF-8 input and a known repeating key. Inspect result bytes and text with this browser-based learning tool.

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Ciphers, Hashes & Passwords

Password Generator

Generate secure passwords for free. Customize length and character sets.

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Ciphers, Hashes & Passwords

Hash Generator

Compute SHA-1, SHA-256, SHA-384 or SHA-512 hashes of text or files in your browser. Handy for verifying file integrity and downloads.

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Images, Design & QR

Image Compressor

Compress image files and compare the result as you adjust quality and dimensions for websites or social media.

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Images, Design & QR

Image Converter

Convert between PNG, JPG, WebP and GIF. Preserve transparency or optimize to WebP.

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Images, Design & QR

QR Code Generator

Generate QR codes from URLs or text for free. Customize colors and sizes.

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Images, Design & QR

Color Converter

Convert between HEX, RGB and HSL. Pick colors directly with the color picker.

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Images, Design & QR

Color Palette Generator

Generate palettes from a base color using complementary, analogous, triadic and monochrome schemes. Copy HEX, RGB and HSL codes for your designs.

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Images, Design & QR

Image Resizer

Resize images by pixels, percentage or longest side. Keep the aspect ratio and get the perfect size for websites, social media or document attachments.

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Images, Design & QR

QR Code Reader

Decode a QR code from an image — screenshots or photos — and copy the text. Everything is processed locally in your browser; nothing is uploaded.

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Images, Design & QR

Contrast Checker

Calculate the contrast ratio between text and background colors and check WCAG conformance (AA, AAA) instantly — for readable, accessible color combinations.

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Images, Design & QR

Image Cropper

Crop images right in your browser for free. Drag the frame, choose ratios like 1:1 or 16:9, and save as PNG, JPEG or WebP. No upload, no sign-up.

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Images, Design & QR

Image Merger

Combine multiple images into one — horizontally or vertically, with optional gaps. Save as PNG or JPEG. Everything runs locally in your browser.

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Images, Design & QR

Image Blur & Mosaic

Blur or pixelate parts of an image right in your browser. Drag over faces, names or addresses to hide them in screenshots and photos. Nothing is uploaded.

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Images, Design & QR

Image Background Transparency

Make the background of an image transparent in your browser. Click the color to remove and export a transparent PNG - ideal for logos and screenshots with solid backgrounds. Nothing is uploaded.

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Images, Design & QR

Image Rotate & Flip

Rotate images in 90° steps or flip them horizontally and vertically in your browser. Ideal for fixing phone photo orientation and creating mirrored images. Export as PNG, JPEG or WebP - nothing is uploaded.

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Images, Design & QR

Image Palette Extractor

Upload an image and extract its dominant colors as a palette. Choose 4, 6 or 8 colors and copy HEX or RGB codes with one click. Everything runs locally in your browser.

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PDF Editing

PDF Merge

Combine multiple PDF files into one. Reorder pages with simple drag and drop.

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PDF Editing

PDF Split

Split PDFs by page range, or extract specific pages into a new file.

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PDF Editing

Rotate PDF

Rotate PDF pages by 90 or 180 degrees and save the result for free. Process every page or a selected range locally in your browser without uploading the file.

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Dates & Time

Unix Timestamp Converter

Convert between Unix timestamps and dates. Grab the current timestamp with one click.

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Dates & Time

Date Calculator

Calculate the difference between two dates in days. Add or subtract days from any date.

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Dates & Time

Age Calculator

Calculate your exact age from your birth date, including days until your next birthday.

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Dates & Time

Timer & Stopwatch

Countdown timer and stopwatch right in your browser. Great for cooking, studying, workouts and timing.

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Dates & Time

Timezone Converter & World Clock

See the current time in major cities like Tokyo, New York and London, plus the time difference from your base city. Handy for calls and travel planning.

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Dates & Time

Rokuyo Calendar & Lunar Date

Pick a date to instantly see its Rokuyo (Taian, Butsumetsu...), lunar date, Chinese zodiac and solar terms. Handy for choosing wedding, moving or opening dates.

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Dates & Time

Japanese Era (Wareki) Converter

Convert between Japanese era years (Meiji to Reiwa) and Gregorian years both ways. Era boundary dates are handled exactly - handy for filling in forms.

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Dates & Time

Time Duration Calculator

Find the duration between two times, or add and subtract hours and minutes. Times past midnight are handled automatically - great for work estimates.

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Calculations & Units

Discount Calculator

Calculate final price and savings for one or two percentage discounts. Stack 30% off with 10% off to see the true 37% effective discount.

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Calculations & Units

Tax Calculator

Calculate tax-included and tax-excluded prices with automatic tax amounts. Supports 10%, 8% and custom rates.

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Calculations & Units

Unit Converter

Convert length, weight and temperature instantly. Meters, inches, kilograms, pounds and more.

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Calculations & Units

Calculator

A free calculator that runs in your browser. Four basic operations, percentage, sign toggle and full keyboard support.

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Calculations & Units

Percentage Calculator

Three modes for instant percentage math: X% of a total, X as a % of Y, and increase or decrease by X%.

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Calculations & Units

Split Bill Calculator

Split a bill evenly from the total and number of people. Choose how to round the remainder - up, down, nearest, or the organizer pays the difference.

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Calculations & Units

Area & Volume Calculator

Calculate the area of 2D shapes (square, rectangle, triangle, circle) and the volume of 3D shapes (cube, cylinder, sphere). Any unit, with liter conversion.

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Calculations & Units

Loan Repayment Calculator

Calculate the monthly payment of a loan from the amount, rate and term, with total repayment and a year-by-year schedule for car, home or student loans.

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Calculations & Units

Compound Interest Calculator

See how savings grow with compound interest. Enter an initial amount, monthly contribution, rate and term to get the final value, total gain and a yearly table.

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Calculations & Units

Margin Calculator

Calculate profit, margin and markup from cost and selling price, or work backwards from a target margin to a price. Made for online shop sellers.

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Calculations & Units

Fuel Cost Calculator

Calculate the fuel needed and its cost from distance, efficiency and gas price, including the cost per kilometer. Handy for trips and expense reports.

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Notes

Browser Notepad

A free notepad that runs entirely in your browser. Your notes are saved automatically on your device and restored next time.

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Notes

Test Account Notes (Plain Text)

Save multiple accounts (title, username, password) for test environments and copy them in one click. Data stays in your browser and is never uploaded.

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Health Calculators

BMI Calculator

Calculate your BMI from height and weight, with the Japanese classification and healthy weight range.

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Health Calculators

Calorie & BMR Calculator

Calculate your basal metabolic rate (BMR) and daily calorie needs from height, weight, age and activity level, plus targets for losing or gaining weight.

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Random Picks & Games

Palindrome Checker

Check whether your text is a palindrome instantly. Supports hiragana, katakana and Latin letters.

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Random Picks & Games

Dice Roller

Roll any number of dice - 4-sided, 6-sided, 20-sided and more. A simple tool for fun and games.

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Random Picks & Games

Roulette Spinner

Spin a roulette to pick one item from your list. Great for choosing lunch or taking turns.

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Random Picks & Games

Daily Fortune

Check today's fortune from your birthday and blood type. Includes lucky item, lucky color and lucky number.

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Random Picks & Games

Reaction Time Test

Click the instant the screen turns green! Measure your reaction time 5 times and beat your record.

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Random Picks & Games

Number Guessing Game

Guess the secret number from 1 to 100. Use the hints to minimize your attempts and beat your record.

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Random Picks & Games

Random Number Generator

Generate random numbers in any range. Duplicate control and sorting included - ideal for draws and raffles.

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Random Picks & Games

Chinese Zodiac Finder

Instantly find the Chinese zodiac animal (Rat, Ox, Tiger...) for any Gregorian year, with a 12-year table around it — handy for New Year cards and trivia.

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Random Picks & Games

Typing Speed Test

Type the shown text and measure your typing speed, accuracy and misses. Three difficulty levels are included. Everything runs locally in your browser.

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