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Calculators, file converters and developer utilities. Fast, free and private — tools run in your browser, so your files and inputs aren't uploaded.
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🆕 New tools
- NEWPosition Size CalculatorDecide what you are willing to lose first. Enter your account size, risk per trade, entry and stop-loss, and the calculator works out how many shares that allows — then measures each target in multiples of that risk and shows what a run of stopped-out trades would do to the account.
- NEWProfit Margin CalculatorEnter what one unit costs you and what you sell it for. You get margin and markup side by side, a check of what your percentage really means, the price a target margin needs and how many units cover your fixed costs.
- NEWROI & CAGR CalculatorEnter what you put in, what came out and how long it took — for up to three investments. You get total ROI, the simple yearly average, the compound annualized ROI and CAGR together, with a plain explanation of why they disagree.
- Retirement CalculatorEnter your age, savings, monthly contribution and the income you want later. You get a savings target, your projected balance, the gap between them and how much more to save each month to close it.
- Credit Card Payoff CalculatorEnter your balance and APR, then either the amount you can pay each month or the month you want to be done. You get the payoff time, the interest, and how both compare with paying only the minimum.
- Debt Payoff CalculatorList what you owe, add what you can pay on top of the minimums, and this works out when each debt clears — ordering them by rate, by balance, and against doing nothing at all.
- Rent vs Buy CalculatorBuying is not cheaper or dearer than renting — it is cheaper after a certain number of years. Enter a home you would buy and a place you would rent, and this finds the year the two cross.
- Home Affordability CalculatorEnter what you earn, what you owe and what you have saved. This works backwards to the price a lender is likely to support — and the monthly payment that comes with it.
⭐ Popular tools
- Compound Interest CalculatorSee how a starting balance and regular deposits grow over time, year by year — with interest, contributions and effective annual rate separated out.
- Mortgage CalculatorEnter a price, down payment and rate to see the full monthly payment — not just principal and interest — with the amortization schedule and the date PMI falls away.
- Home Affordability CalculatorEnter what you earn, what you owe and what you have saved. This works backwards to the price a lender is likely to support — and the monthly payment that comes with it.
- Rent vs Buy CalculatorBuying is not cheaper or dearer than renting — it is cheaper after a certain number of years. Enter a home you would buy and a place you would rent, and this finds the year the two cross.
- Loan CalculatorEnter an amount, rate and term to see the monthly payment, the real cost in interest, and how much an extra payment each month would save you.
- Debt Payoff CalculatorList what you owe, add what you can pay on top of the minimums, and this works out when each debt clears — ordering them by rate, by balance, and against doing nothing at all.
- Credit Card Payoff CalculatorEnter your balance and APR, then either the amount you can pay each month or the month you want to be done. You get the payoff time, the interest, and how both compare with paying only the minimum.
- Retirement CalculatorEnter your age, savings, monthly contribution and the income you want later. You get a savings target, your projected balance, the gap between them and how much more to save each month to close it.
- Stock Average Down / DCA Average Cost CalculatorAdd each purchase you made, get your true average cost per share, then plan the next buy — either by target average or by share count.
- Percentage CalculatorFive common percentage calculations on one page. Results update as you type, and nothing you enter leaves your browser.
- Image CompressorDrop in photos, choose a quality level, and get noticeably smaller files. Everything runs inside this tab, so your images never touch a server.
- HEIC to JPG Converter (and Everything Else)Turn iPhone HEIC photos into JPG in seconds, or convert between PNG, WebP, AVIF and more. Files are decoded on your own device and never uploaded.
- Merge and Split PDFJoin several PDFs into one, pull out the pages you need, or burst a document into separate files. Everything happens in this tab, so confidential documents stay on your machine.
- QR Code GeneratorMake a QR code for a link, your Wi-Fi password, a contact card or a text message. The code is drawn in your browser and contains your data directly — no redirect, no account, no expiry.
- JSON Formatter & ValidatorPaste JSON, get it beautified, minified or validated with the exact line and column of the problem. Everything runs in your browser.
- Typing Speed TestType the words as they appear and find out your real speed — net WPM, raw WPM and accuracy, with every keystroke scored as you go.
- Unit ConverterPick a category, choose two units and type — the conversion runs in both directions as you go, with exact factors and a quick reference table for each category.
- Word CounterPaste or type your text and watch the counts update instantly — words, characters, reading time, keyword density and a readability score, all computed in your browser.
- Image ResizerDrop in photos and get them back at exactly the size you need — by pixels, by percentage, or fitted into a preset box. Everything runs in this tab, so your images never leave your device.
- Password GeneratorBuild a random password or a memorable passphrase with real cryptographic randomness. Entropy, strength and crack time are shown for the exact options you picked — and nothing ever leaves your browser.
- Time Zone ConverterPick a date and time in one city and read it in every other city that matters to you — with the UTC offset, the day difference and a colour band showing whether it lands in someone's working day.
- Daily Word PuzzleOne five-letter word, six guesses, and a fresh puzzle for everybody at midnight UTC. Colour clues after every guess, and a spoiler-free grid you can share.
- 2048Slide, merge, repeat. Get two matching tiles together and they fuse into their sum — keep going until a 2048 tile appears, or until the board jams up.
Finance Calculators
Browse all →- Compound Interest CalculatorSee how a starting balance and regular deposits grow over time, year by year — with interest, contributions and effective annual rate separated out.
- Mortgage CalculatorEnter a price, down payment and rate to see the full monthly payment — not just principal and interest — with the amortization schedule and the date PMI falls away.
- Home Affordability CalculatorEnter what you earn, what you owe and what you have saved. This works backwards to the price a lender is likely to support — and the monthly payment that comes with it.
- Rent vs Buy CalculatorBuying is not cheaper or dearer than renting — it is cheaper after a certain number of years. Enter a home you would buy and a place you would rent, and this finds the year the two cross.
- Loan CalculatorEnter an amount, rate and term to see the monthly payment, the real cost in interest, and how much an extra payment each month would save you.
- Debt Payoff CalculatorList what you owe, add what you can pay on top of the minimums, and this works out when each debt clears — ordering them by rate, by balance, and against doing nothing at all.
- Credit Card Payoff CalculatorEnter your balance and APR, then either the amount you can pay each month or the month you want to be done. You get the payoff time, the interest, and how both compare with paying only the minimum.
- Retirement CalculatorEnter your age, savings, monthly contribution and the income you want later. You get a savings target, your projected balance, the gap between them and how much more to save each month to close it.
- Stock Average Down / DCA Average Cost CalculatorAdd each purchase you made, get your true average cost per share, then plan the next buy — either by target average or by share count.
- FIRE CalculatorFind the portfolio size that would cover your spending, then see the year you could reach it at your current savings rate.
- Dividend Reinvestment CalculatorSee how reinvested dividends compound over time — ending value, share count, yield on cost, and how much reinvestment adds versus taking the cash.
- Salary to Hourly CalculatorEnter what you earn and how often you are paid, and get every other pay period instantly — hourly, daily, weekly, bi-weekly, semi-monthly, monthly and yearly.
- Inflation CalculatorEnter an amount, an inflation rate and a number of years to see what things will cost, what your money will really be worth, and how much prices rise in total.
- ROI & CAGR CalculatorEnter what you put in, what came out and how long it took — for up to three investments. You get total ROI, the simple yearly average, the compound annualized ROI and CAGR together, with a plain explanation of why they disagree.
- Profit Margin CalculatorEnter what one unit costs you and what you sell it for. You get margin and markup side by side, a check of what your percentage really means, the price a target margin needs and how many units cover your fixed costs.
- Position Size CalculatorDecide what you are willing to lose first. Enter your account size, risk per trade, entry and stop-loss, and the calculator works out how many shares that allows — then measures each target in multiples of that risk and shows what a run of stopped-out trades would do to the account.
Everyday Calculators
Browse all →- Percentage CalculatorFive common percentage calculations on one page. Results update as you type, and nothing you enter leaves your browser.
- Age CalculatorEnter a date of birth and get an exact age — plus the weekday you were born on, your next birthday, and your star sign and Chinese zodiac animal.
- Date Difference CalculatorTwo calculators in one — the exact gap between two dates, including business days, and a date-maths mode that adds or subtracts any period.
- Tip CalculatorEnter the bill, pick a tip percentage and say how many people are paying — the tip, the total and each person's share update as you type.
- Discount CalculatorFind the final price, the money saved and the true percentage off — including the case where an extra discount stacks on top of a sale price.
- Unit ConverterPick a category, choose two units and type — the conversion runs in both directions as you go, with exact factors and a quick reference table for each category.
- BMI CalculatorEnter your height and weight in metric or imperial units to see your BMI, where it sits on the WHO scale, and the weight range that matches your height. It is a screening number, not a verdict.
- Sleep CalculatorTell the calculator when you need to wake up — or when you are heading to bed — and it counts whole sleep cycles to suggest times that land in light sleep rather than the middle of a cycle.
- Fuel Cost CalculatorEnter the distance, your car's fuel efficiency and the price at the pump to see the fuel used, the total cost, the cost per person and the cost of every mile or kilometre.
Text Tools
Browse all →- Word CounterPaste or type your text and watch the counts update instantly — words, characters, reading time, keyword density and a readability score, all computed in your browser.
- Case ConverterPaste text once and get every capitalisation style at the same time — sentence, title, camel, snake, kebab and a few playful ones — each with its own copy button.
- Text DiffPaste two versions of anything — a paragraph, a config file, a contract clause — and see exactly what changed, line by line and word by word, without uploading a thing.
- Lorem Ipsum GeneratorMake as much placeholder text as your mockup needs — in classic Latin or three alternative flavours — with optional HTML tags and a seed that reproduces the exact same text every time.
File Tools
Browse all →- Image CompressorDrop in photos, choose a quality level, and get noticeably smaller files. Everything runs inside this tab, so your images never touch a server.
- HEIC to JPG Converter (and Everything Else)Turn iPhone HEIC photos into JPG in seconds, or convert between PNG, WebP, AVIF and more. Files are decoded on your own device and never uploaded.
- Merge and Split PDFJoin several PDFs into one, pull out the pages you need, or burst a document into separate files. Everything happens in this tab, so confidential documents stay on your machine.
- EXIF RemoverFind out what your photos are quietly telling people — camera, timestamp, even GPS coordinates — and strip it all out before you share them.
- QR Code GeneratorMake a QR code for a link, your Wi-Fi password, a contact card or a text message. The code is drawn in your browser and contains your data directly — no redirect, no account, no expiry.
- Image ResizerDrop in photos and get them back at exactly the size you need — by pixels, by percentage, or fitted into a preset box. Everything runs in this tab, so your images never leave your device.
Developer Tools
Browse all →- JSON Formatter & ValidatorPaste JSON, get it beautified, minified or validated with the exact line and column of the problem. Everything runs in your browser.
- Cron Expression GeneratorWrite a cron expression in Unix, Spring or Quartz form, read what it actually means in English, and see the next ten fire times in UTC and your local time.
- Base64 Encoder & DecoderConvert text, files and data URIs to and from Base64 with correct UTF-8 handling, a URL-safe option and MIME line wrapping. Nothing is uploaded.
- Unix Timestamp ConverterA live epoch clock, instant timestamp-to-date conversion in UTC and your local time, a date-to-timestamp direction, and a batch mode for whole log columns.
- Password GeneratorBuild a random password or a memorable passphrase with real cryptographic randomness. Entropy, strength and crack time are shown for the exact options you picked — and nothing ever leaves your browser.
- UUID GeneratorCreate random or time-ordered identifiers in bulk, format them for JSON, CSV or a SQL insert, and paste any existing id to find out which version it is and when it was made.
- Hash GeneratorCompute SHA and CRC32 digests of text or files entirely in your browser, switch between hex and Base64, sign messages with HMAC, and check two hashes against each other.
- URL Encoder & DecoderEncode or decode percent-escapes with precise error messages, rebuild a query string from an editable table, and see exactly which part of a URL is which.
- JWT DecoderPaste a JWT to read its header and payload, understand every claim in plain English and see at a glance whether it is still valid. The signature is not verified, and the token never leaves your browser.
- CSV ⇄ JSON ConverterPaste or drop a file and convert between CSV and JSON in both directions, with a proper RFC 4180 parser that handles quotes, commas inside values and multi-line fields.
- Color ConverterPaste a colour in any notation and get every other one back, plus tints, shades and harmony palettes and a contrast check that tells you straight out whether text will be readable.
Games & Tests
Browse all →- Typing Speed TestType the words as they appear and find out your real speed — net WPM, raw WPM and accuracy, with every keystroke scored as you go.
- Daily Word PuzzleOne five-letter word, six guesses, and a fresh puzzle for everybody at midnight UTC. Colour clues after every guess, and a spoiler-free grid you can share.
- 2048Slide, merge, repeat. Get two matching tiles together and they fuse into their sum — keep going until a 2048 tile appears, or until the board jams up.
- MinesweeperClear the field without stepping on a mine. Every number tells you how many mines touch that square — the rest is deduction, and the first click is always safe.
- Memory MatchFlip two cards, find the matching emoji, clear the board. Three board sizes, a live timer, a star rating and your personal bests kept on this device.
- Reaction Time TestThe classic red-to-green reflex test. Wait for the colour change, click as fast as you can, and see how your milliseconds stack up against the typical human range.
- Aim TrainerClick the targets as fast as you can. Two modes, three target sizes, and honest numbers — hits, misses, accuracy and targets per second — all tracked in your browser.
- Tic Tac ToePlay noughts and crosses against three levels of computer opponent — or pass the device and play a friend. Scores are kept on this device.
- Simon SaysFour pads, one growing sequence. Watch it play, repeat it back, and each time you succeed the pattern gets one step longer and a little faster.
Instant results
No sign-up, no waiting for a server round trip. Results update as you type.
Formulas you can check
Every calculator explains its method and shows worked examples, and the logic is covered by automated tests.