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How to calculate retirement, which runs two chained phases: years of compound interest while you save, then years of withdrawals while you spend. Worked across starting at 30 with $50,000 and adding $1,000 a month at a 7% return - $2,376,362 by 65, of which $1,906,362 (80.2%) is interest - the 4% rule saying you need 25 times your annual spending ($1,200,000 for $4,000 a month), how the same plan built at 40 or 50 falls to $1,096,343 or $459,410, and why inflation turns that 7% into only about 4.4% in real terms.

How to calculate credit card payoff month by month: each month the card adds the balance times the monthly rate (the APR divided by 12, so 19.99% is about 1.67%) as interest, then your payment comes off the top, which is why early payments go mostly to interest. Worked across $5,000 at 19.99% paying $250 a month - 25 months, $1,132.29 of interest, $6,132.29 paid - why the 2% minimum payment never reaches zero and the interest runs past $20,000 over 50 years, how adding just $100 a month saves $373.96, when to pay the smallest or the highest-rate card first, and what the freed-up $250 a month can earn once invested.

How to calculate CAGR, the compound annual growth rate: the working formula (ending value divided by beginning value)^(1/n) - 1, worked across $10,000 to $20,000, $50,000 and $100,000, why CAGR is the geometric mean of growth rather than the arithmetic one, how it differs from the total return and a simple average (the -50% then +100% path that nets to zero), when a CAGR can be negative and how to handle fractional years, why irregular cash flows require IRR or its money-weighted annualized cousin XIRR instead, and why a CAGR should always be read next to maximum drawdown and the Sharpe ratio.

How to calculate the rule of 72: divide 72 by the whole-number annual rate to get the years to double, worked across 4%, 6%, 8% and 10%, why the true constant is 69.3 and 72 is used for its divisibility, when the rule of 70 or 73 is a closer fit, tripling with 114 and quadrupling with 144, using the rule in reverse to find the return you need, and how a nominal return silently ignores inflation so long-horizon goals should work in the real rate.

How to calculate stop loss and take profit: the two levels in percentage and price mode, a worked $100 long and short example (stop $95, take $110, risk $500, reward $1,000, ratio 1:2), how to read the risk/reward ratio and the break-even price, sizing the stop off ATR instead of a round number, the risk amount and the risk percentage, how much of the account to risk per trade, and where the stop must sit relative to the liquidation price.

Black-Scholes option pricing explained: the full formula with every symbol, a worked $100 at-the-money call with 60 days to expiry (d1, d2, N(d1), N(d2), call $4.45, put $3.63), how each of the five inputs moves the price, the Greeks, implied volatility as the formula run in reverse, the model assumptions, and where it breaks for American and crypto options.

Staking APY explained: the difference between APR and APY, the compounding formula for any frequency V = P · (1+r/n)^(n·t), a fully worked $10,000 example at 10% across four frequencies, what sets a chain's staking yield, how to reverse-convert an advertised APY to its quoted rate, and the comparison against liquidity provision, lending and borrowing cost.

Impermanent loss explained: the AMM formula 1 − 2√r/(1+r) and the weighted general case, a worked $10,000 50/50 example at 2x, 4x and 10x price moves, how pool weights (50/50 vs 80/20 vs 95/5) dampen the loss, why Uniswap v3 out-of-range moves lock it in, and how to check whether trading fees actually cover your exposure.

Funding rate explained: the payment formula notional × rate × (hours held / 8) × sign, a worked $10,000 example at baseline and elevated rates, what positive and negative funding say about positioning, how to annualize the 8-hour rate, and why funding arbitrage is not risk-free.

Liquidation price explained: the formula entry × (1 − collateral / position size ± maint margin), a worked BTC example at 10x, why the buffer shrinks as 1/leverage, how maintenance margin and fees close the gap, how to push the price further away, and why your stop-loss must sit before it.

Position sizing explained: the formula shares = (account × risk%) / stop distance, a worked example for long and short, why the 1–2% rule exists, where the stop comes from, how to use a position sizing calculator, and how it combines with the Kelly criterion.

The Kelly criterion defined, the formula (b·p − q)/b step by step, worked examples, full vs fractional Kelly, what a negative Kelly means, how to apply it to betting and trading, and how to calculate it in Excel.

The Sharpe ratio defined, the formula (Rp − Rf) / σ step by step, four worked examples, what counts as a good Sharpe, how to calculate it in Excel, and how it compares to Sortino, Calmar, Treynor and information ratio.

Maximum drawdown (MDD) defined, the formula step by step, a full worked example, drawdown duration and recovery, and what counts as an acceptable MDD for funds, prop firms and crypto.

How to write prompts for text-to-image models: the eight-part structure, the visual vocabulary image models respond to, worked examples, and mistakes to avoid.

How to write prompts for text-to-video and image-to-video models: the six-part structure, camera vocabulary, worked examples, and mistakes to avoid.

Convert between decimal, fractional and American betting odds with the exact formulas, worked examples, and implied-probability math.

Learn how to calculate the difference between two dates in days, weeks, months and business days, with a worked example, common pitfalls like inclusive counting and timezones, and tools that do it for you.

Learn what IRR (internal rate of return) is, how the NPV = 0 equation works, a five-year worked example with trial rates, and when to prefer IRR over ROI.

Learn how to calculate ROI (return on investment) with the exact formula, worked examples for stocks and real estate, and how ROI differs from CAGR and ROE.

Learn how to calculate pip value in forex with the exact formula, worked examples for major and JPY pairs, and how to use it to size positions with a 1% risk rule.

Generate strong, random passwords instantly with our free online password generator. Learn what makes a password secure and how to create unique passwords for every account.

Learn the compound interest formula with step-by-step examples. Use our free calculator to see how your investments grow over time with daily, monthly, or annual compounding.

Compare the best free loan calculators online. Learn how to calculate monthly payments, total interest, and amortization schedules without entering your bank details.

Paste "Hello World! How are you today?" and the Text Reverser returns "?yadot uoy era woH !dlroW olleH" in character mode and "today? you are How World! Hello" in word mode, with line mode flipping the order of the lines, all computed in the browser.

Enter a 150.00 high, a 100.00 low and a bullish trend: the calculator returns the seven retracement levels from 150.00 down to 100.00, the key 130.90 support at 38.2 percent, and three extensions above the high, the 180.90 target at 161.8 percent being the farthest practical one, all computed in the browser.

Enter a 2,000,000 loan, a 30 year term, a 4.2 percent rate and a 500,000 early payment after 24 months: the calculator returns a 9,780.34 monthly payment, a 1,430,515.72 balance after the payment, 778,315.25 in interest saved by shortening the term to 205 months, and a 7,247.25 reduced payment if you keep all 336 months, all computed in the browser.

Enter a 150 stock price, a 5.50 EPS and a 25 percent growth rate: the calculator returns a 27.27 P/E, a 3.64 percent earnings yield, a 1.09 PEG inside the fair-value band and a 275.00 fair price under the PEG = 2 rule, shows the growth ladder from 2.73 at 10 percent down to 0.91 at 30 percent, and explains the three thresholds, all in the browser.

Enter a 5.00 option price, a 100 underlying, a 105 strike, 30 days to expiry and a 5.0 percent rate: the calculator solves 60.35 percent implied volatility for the call, 16.28 percent for the put at the same price, shows the IV ladder from 0.73 at 20 percent up to 3.84 at 50 percent, and explains Newton iteration and vega, all in the browser.

Enter face value 100, conversion price 5, stock price 6, bond price 110 and floor 95: the calculator returns the 20 shares you receive, the 120.00 conversion value, the -8.33% conversion premium and the 15.79% floor premium, with the formulas and what a positive or negative sign means, all in the browser.

Paste any text and get words, characters with and without spaces, sentences, paragraphs, lines and reading time at 200 words a minute next to speaking time at 130, the ten most frequent characters, a five-way split into uppercase, lowercase, digits, special and whitespace, plus four case rewrites, all local in the browser.

Turn a nominal rate and an inflation rate into a real rate: the exact Fisher answer (1 + i) / (1 + π) - 1 next to the quick subtraction i - π, with the gap between them printed, plus a 112-cell matrix of real rates for nominals from 2% to 15% against inflation from 1% to 8%, color-banded, all local in the browser.

Seven bitwise operations on 32-bit words: AND, OR, XOR, NOT A, NOT B, left and right shift, with worked numbers (12 AND 10 = 8), the arithmetic right shift that keeps the sign, the 31 mask on shift amounts, and five output bases at once, all local in the browser.

Generate the full app icon set from one photo: a cover-crop turns any rectangle into a centered square, one high-quality resample feeds all 36 sizes from 16 to 1024 pixels across iOS, Android, web, macOS and Windows, the ZIP carries 36 PNG plus a PWA manifest with a 12-character short_name and a 14-entry iOS Contents.json, and the file name my-cool-app-icons.zip derives from the app name, everything local.

Encrypt and decrypt text with AES-GCM in the browser: a 12-byte plaintext becomes a 28-byte ciphertext carrying a 16-byte authentication tag, keys of 32, 48 or 64 hex characters select AES-128, 192 or 256, the 24-character IV is 12 bytes, reusing a key and IV pair triggers a warning, and the base64 output is 40 characters for 12 bytes, 156 for 100, everything local.

Merge audio clips in the browser: 30 s, 45 s and 15 s become one 1:30 file after decode, trim, reorder and sample-rate unification, exported as 16-bit stereo WAV at 176400 bytes per second or as 128 kbps MP3 at 16000 bytes per second, an 11-to-1 size split, with the whole pipeline local and no upload.

Convert a Unix timestamp to a date in the browser: 1789689600 reads back as Friday, September 18, 2026 at 00:00 UTC in six lines — ISO, UTC, local, readable, date and time — and the reverse mode parses the wall clock of September 18, 2026 at 12:00 into seconds and milliseconds, with the digit-count rule that reads ten digits as seconds and eleven to thirteen as milliseconds.

Calculate the exact age in the browser from a date of birth: born January 15, 1990 read as of September 18, 2026 gives 36 years 8 months 3 days, a total of 13395 days or 1913 weeks or 321480 hours, and a countdown of 119 days to the next birthday on January 15, 2027, with the month-day borrow rule and the February 29 rollover explained.

Add 90 days, 3 weeks, 6 months or 1 year to a start date in the browser: January 15, 2026 plus 90 days lands on April 15, plus 21 days on February 5, with month-end clamping that turns 31 January plus 1 month into 28 February, and input clamps at 3650 days, 520 weeks, 120 months and 10 years.

Compute the emergency fund in the browser: six expense lines of 1500, 400, 200, 300, 150, and 250 sum to 2800 a month, six coverage months give a 16800 target, savings of 5000 leave a gap of 11800 with 29.8 percent progress, and 500 a month closes the gap in 24 months, with the fund placed after high-interest debt and before savings goals.

Compute the profit factor in the browser: gross wins of 1800 over gross losses of 700 is 2.57, an Excellent tier, with a 60 percent win rate and an expectancy of 220, and a zero-loss sample shows infinity, then compare the factor against win rate, expectancy, drawdown, and Sharpe before sizing a position.

Convert text to binary in the browser: the letter A with code point 65 becomes 01000001, Hi becomes 01001000 01101001, a space with code 32 becomes 00100000, and the smiley emoji with code point 128512 needs 17 bits, 11111011000000000, then read the groups back to text and check which sibling encodings like Base64 and Morse fit the job.

Compute the risk reward ratio in the browser: an entry of 100, a stop of 90, and a target of 120 give a 10 dollar risk and a 20 dollar reward per share, a 1 : 2.00 ratio on a 100 share position, a required win rate of 33.3 percent, risk and reward of 10.00 percent and 20.00 percent of entry, totals of 1,000 and 2,000 dollars, a good evaluation, and a plus 50.0 percent edge at a 50 percent win rate.

Compute the P/E ratio, the P/B ratio, and the fair value from two industry averages in the browser: a price of 150 on EPS of 5 is a 30 times P/E against an 18 times industry, a 1.88 times P/B against 2.5, a market cap of 150.00 million from one million shares, fair values of 90 and 200 averaging 145, a plus 66.7 percent earnings premium, a minus 25.0 percent book discount, and an overvalued verdict at minus 3.4 percent.

Compute the contract value, the required margin, and the return on margin for a futures position in the browser: 50,000 at 10 percent margin posts 5,000, a 1 percent move is 500 and 10 percent on margin, a 10 percent move is 100 percent of the posted margin from 2 to 50 times leverage, and funding at 0.01 percent per 8 hours costs 5,475 a year, 109.5 percent of the margin.

How to format HTML online: the markup is pasted into the browser and both modes run locally with nothing uploaded, so a 458-character page written across 28 lines comes back formatted at 390 characters over 27 lines with two or four space indentation, or minified to 281 characters on a single line, a 38.6 percent reduction, with every script, textarea and pre block protected byte for byte, comments stripped in minify mode, and a fixed inline element list keeping prose readable: structure honest, payloads intact.

How to use an online image cropper: the file is read with a FileReader and drawn onto a canvas in your browser, with nothing uploaded, and a 4000 × 3000 photo cut to 1:1 returns 3000 × 3000 pixels, a 16:9 cut returns 4000 × 2250, a 4:3 cut keeps the full 4000 × 3000 frame, with seven ratio presets including A4, a quality default of 92, and PNG, JPEG or WebP export: the frame you choose, at full resolution.

How to use a Monte Carlo stock simulator: run five hundred geometric Brownian motion paths from a 150 dollar share at a 10 percent annual return and a 20 percent volatility, and the year lands with a mean of 165.78 dollars, a median of 162.49, a 65.54 percent probability of profit, a 5th percentile at 116.94 and a 95th at 225.79. Over five years the median climbs to 223.77 with an 81.45 percent chance of profit: the full distribution, not one forecast.

How to calculate implied probability: decimal odds of 2.10 hide 47.62 percent, a three-way market at 2.10, 3.40 and 3.60 totals 104.81 percent with a 4.81 point overround, normalizing gives a fair home win of 45.43 percent, a 55 percent estimate beats the 47.62 percent break-even for plus 15.5 percent expected value, and a 0.50 delta means 50 percent in the money at a 103 breakeven on a 100 strike.

How to calculate DRIP, the dividend reinvestment plan: $10,000 at $100 a share plus $500 a month, a 4 percent dividend growing 5 percent a year and a price growing 7 percent a year, ends at $431,946 on $130,000 invested over 20 years, 232.3 percent, with $95,713 of final value created by reinvested dividends alone.

How to calculate DCA, the future value of an ordinary annuity: a $500 monthly contribution at 8 percent annual return for 20 years compounds 240 contributions to $294,510 on $120,000 invested, a 145.4 percent gain. The same $120,000 invested as a lump sum at 8 percent reaches $559,315, so DCA trails by $264,805, because money already invested compounds immediately. The year-by-year schedule crosses in year ten, when the account first earns more in a year than you contribute. Return moves the answer most: 5 percent ends at $205,517, 10 percent at $379,684; frequency barely matters, a 1.5 percent spread.

How to calculate market cap, which is one multiplication: the current stock price times the total shares outstanding. A stock at $150 with 8,000,000,000 shares has a $1,200,000,000,000 market cap, a mega cap, since the tier starts at $200 billion. Two companies can both trade at $20 a share and be 25 times different in size because size is set by the share count, a $50,000,000,000 large cap versus a $2,000,000,000 mid cap. With the share count fixed, a 50% move is the same 50% move in market cap, and the P/E divides the $1.20 trillion by a year of earnings, 12 if the company earns $100,000,000,000 a year.