How GPA Is Actually Calculated, Weighted and Unweighted
GPA is an average, but not the one most students compute. Credits change the weighting, AP classes change the scale, and every school gets to pick its own rules.
Guides and write-ups
Longer pieces on the jobs the tools do: getting a file under a size limit, stopping Excel from damaging your data, working out what to charge. Written by the person building them.
75 articles
Why Your GIF Is 20MB When the Video Was 2MB
A GIF stores every frame as a picture. A video stores what changed. That one difference explains the file size, the grainy colours, and why most platforms quietly convert your GIF anyway.
Cron Expressions: Five Fields and the Three Mistakes That Bite
Cron is five numbers and a surprising amount of folklore. The syntax takes ten minutes. The reasons a job silently ran on the wrong day take longer.
Deductible, Copay, Coinsurance, Out-of-Pocket Max: One Worked Year
Four words on every US health plan, and most people can define two of them. Here is a single year of bills run through all four, so the numbers stop being abstract.
Why Your Due Date Is a Guess, and What It Is Actually For
About one baby in twenty arrives on the due date. The date still matters, just not for the reason most people think.
The Gallon Problem: Why UK and US MPG Are 20% Apart
A car rated 36 MPG in Britain and 30 MPG in America can be the same car. Two different gallons, one number, and a lot of confused comparisons.
UPC, EAN, Code 128 or QR: Which Barcode Do You Actually Need?
Retailers will reject the wrong barcode type outright. The choice comes down to one question, and it is not about the picture.
Base64 Is Not Encryption: Four Things Developers Keep Confusing
Encoding, encryption, hashing and signing look similar in a terminal and do completely different jobs. Mixing them up is how secrets end up in plain sight.
How to Catch Your Own Typos When Your Eyes Refuse To
You proofread the page four times and the error was in the headline. Here is why that happens, and four techniques that work better than reading it again.
What Actually Counts as Overtime (and What Does Not)
Overtime is not paid for long days, weekends or holidays. It is paid for hours over 40 in a fixed workweek. I go through the rule, the exemption test and the traps.
Fair Draws and Strong Passwords: What Random Actually Means
Most random numbers on the web come from a generator that was never meant to be unpredictable. For a giveaway that matters, or a password, that difference is everything.
What Actually Triggers a Crypto Tax Event in the US
The IRS treats crypto as property, not currency. That one sentence is why swapping one coin for another is a taxable disposal and moving coins between your own wallets is not.
What You Can Actually Charge on a Late Invoice
In the UK a late invoice earns interest automatically. In the US it earns nothing unless you said so before the work started. I explain both, with the numbers.
Why Your PDF Is 40MB, and What Actually Shrinks It
Almost every oversized PDF is oversized for one of three reasons. Knowing which one you have tells you whether compression will help or quietly ruin the file.
Working Out Your Net Worth Without Lying to Yourself
Net worth is assets minus debts, which sounds like it takes five minutes. The hard part is valuing things honestly, and most people get the car and the house wrong.
How Much to Charge as a Freelancer (Real Math)
Dividing a salary by 2,080 hours is how freelancers underprice themselves. Here is the real calculation, worked through to $80 an hour, plus the paperwork.
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How to Make an Instagram Grid Post (The Right Way)
One image split across three tiles looks great, until you upload it in reading order and it comes out backwards. Here is the math, the order, and the warning.
Compound Interest Explained With Real Numbers
The same $500 a month grows to $86,542 in ten years and $609,985 in thirty. Waiting a decade to start costs $349,522 and saves you only $60,000.
Does the 1 Percent Rule Still Work?
A $250,000 house renting for $2,000 hits 0.8 percent and fails the rule. It also pencils to a 4.8 percent cap rate. Here is when that matters and when it does not.
How to Analyze a Rental Property: From 30-Second Screen to Yes or No
Screen it fast, then run the real numbers. I take one $350,000 house all the way through NOI, cap rate, DSCR and cash on cash, and end up walking away.
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How to Extract Text From a PDF (Without Uploading)
Some PDFs hand over their words instantly. Others are only pictures of words and need OCR. Here is the three second test that tells you which one you have.
Remove Photo Metadata and Blur Faces Before Posting
A photo leaks in two ways at once: GPS coordinates hidden inside the file, and the faces, plates and screens you can see. Here is how to close both properly.
The Real Costs of a Short Term Rental, Priced Line by Line
A host collects $38,690 and keeps $27,629. Here is every line in between, priced from a real model, including the ones first year hosts never budget for.
What Is Boot in a 1031 Exchange? A $50,000 Withdrawal, a $14,400 Bill
Boot is the part of an exchange the IRS still taxes. Taking $50,000 of cash out of an $846,000 closing costs $14,400, and debt relief counts too.
The 1031 Exchange Timeline: 45 Days, 180 Days, and the Rules That Kill Deals
Both clocks start at the same closing, weekends count, and a qualified intermediary hired one day late ends the exchange. Here is the calendar that works.
Airbnb vs Long Term Rental: The Honest Comparison
Gross revenue said short term wins by nearly double. Net said $27,629 against $14,400, and break-even occupancy told me how much cushion I really had.
Aspect Ratios for Video and Social in 2026: 16:9, 9:16, 1:1 and 4:5
Which aspect ratio each platform wants in 2026, the quick conversion math, safe zones for captions, and why wrong ratios crop your subject out of frame.
The BRRRR Method: An Honest Guide With One Full Worked Deal
Buy, rehab, rent, refinance, repeat, computed end to end on a $120,000 purchase with a $210,000 ARV, including the three places the strategy quietly breaks.
Closing Costs for First-Time Buyers: Every Line, Explained
What actually sits inside the 2 to 5% closing bill on a US home purchase, which lines you can shop or negotiate, and how to read the two documents that matter.
Depreciation Recapture: The Tax Bill Nobody Budgets For
The deduction you enjoyed for years comes back at up to 25% when you sell, and it is charged even if you never claimed it. Here is what that costs.
The 50 Percent Rule Explained, and When to Ignore It
Half of gross rent goes to operating expenses. On a $250,000 rental at $2,000 a month that leaves $12,000 of NOI and a 4.8 percent cap rate. Is it fair?
8 First Rental Property Mistakes, Each Priced in Dollars
The eight errors first-time landlords make most, from expense denial to skipped inspections, with the number each one costs and the habit that prevents it.
HELOC vs Home Equity Loan: Line or Lump Sum, With the Math
A credit line against your house or a fixed second mortgage: how each one works, the interest-only trap, and worked numbers at illustrative rates.
Where Crypto Prices Come From: There Is No Single Price
Why every site shows a different Bitcoin price: order books, spreads, volume-weighted averages, and why your exchange never matches the number you saw.
How to Remove PMI: The 80 Percent Request and the 78 Percent Rule
On a $360,000 loan, PMI runs $150 a month. Asking at 80 percent instead of waiting for automatic termination saves about $2,100. Here is the exact timeline.
Rental Property Depreciation Explained: 27.5 Years and the Trap at the End
Depreciation is the deduction you take without spending a dollar, and the one the IRS assumes you took anyway. Here is the math on a $350,000 rental.
The 70% Rule in House Flipping: When It Saves You and When It Lies
Where the flipper's 70% rule comes from, one worked deal where it protects your profit, one where it rejects a fine deal, and the cost line first flips blow.
SVG vs PNG: When Vectors Win and When Pixels Do
Vector vs raster in plain English: why SVG logos stay sharp at any size, where PNG still wins, and the export gotchas that ruin files in transit.
What a 70% Chance of Rain Actually Means
Probability of precipitation, decoded: what 70% rain really promises, when highs and lows actually happen, and why day 7 of a forecast keeps changing.
The 4.5:1 Rule: A Practical Guide to WCAG Color Contrast
What a contrast ratio actually measures, why 4.5:1 is the line, when large text gets a pass, and how to fix failing brand colors without losing the brand.
Cap Rate vs Cash on Cash Return: One Duplex, Both Numbers
Cap rate grades the property, cash on cash grades your money. I run the same $300,000 duplex both ways and show exactly when leverage flips the answer.
The Crypto Fear and Greed Index, Explained Honestly
What actually goes into the 0 to 100 sentiment score, the contrarian logic behind reading it, and its honest limits as a timing tool for crypto markets.
DSCR Loans Explained: Qualifying on the Property, Not Your W-2
How debt service coverage ratio loans work for rental investors: the ratio itself, why lenders want 1.2 or better, and a worked example you can rerun.
How DNS Actually Works: What Happens When You Type a Domain
What really happens between typing a domain and a page loading: resolvers, record types, TTL, and why DNS propagation is mostly a caching myth.
JSON vs CSV: When Each Format Wins and What Breaks in Between
When JSON beats CSV and vice versa, what breaks in translation between them, why Excel mangles your files, and the conversion habits that prevent it.
The PTO Bridge Method: Turning Public Holidays into Long Breaks
How to stretch limited PTO with holiday bridges: spotting 4-day weekends, worked 2027 US and UK examples, and the booking etiquette that keeps it fair.
WebP vs JPG vs PNG: Which Image Format Actually Wins
An honest format guide with real size math: when WebP wins, when JPG is still fine, when PNG is the only right answer, and how transparency decides it.
What Does It Cost to Sell a House? From $400,000 to the Actual Wire
Commissions after the 2024 NAR settlement, transfer taxes, concessions, and payoff math: I walk a $400,000 sale line by line down to the money that arrives.
What Is a Good Cap Rate? A Worked Fourplex and an Honest Answer
I take a $480,000 fourplex from gross rent down to a 7.29% cap, explain why 'good' depends on market and class, and show how caps move price.
What Your IP Address Actually Reveals (and What It Does Not)
IP geolocation finds infrastructure, not people. What an IP really exposes, why the city is often wrong, and why websites keep using it anyway.
Exchange Rates for Travelers: Why You Never Get the Rate You Googled
The rate on Google is not the rate you get. I break down reference rates, card spreads, and airport kiosks, with the math on what each one really costs.
JWT Tokens: What They Actually Prove (and What They Never Did)
A JWT is three chunks of base64, and two of them are readable by anyone. I explain what the signature proves, why decoding is not verifying, and expiry.
Remote Team Time Zones: Scheduling Without Resentment
Overlap windows, rotating meeting pain, and DST traps: how I schedule across New York, London, and Sydney without anyone taking the 3am call every week.
Running Pace for Beginners: From Couch to Your First 5K
What 6:00 per kilometer actually means, realistic first 5K targets, a split table that adds up to the second, and the pacing mistake that wrecked my first race.
Sleep Cycles and Wake-Up Times: What the 90-Minute Rule Really Buys You
Sleep runs in roughly 90-minute cycles, and waking mid-cycle feels awful. Here is what the sleep math can genuinely do and where it quietly falls apart.
Debt Snowball vs Avalanche: A Worked Example
Same three debts, both methods, month by month. The avalanche saved $460 and one month, and there is still a real case for choosing the snowball.
E-Signatures: When Does a Document Actually Count as Signed?
When does a click or a squiggle count as legally signed in the US and UK? ESIGN and UETA in plain English, plus the evidence I keep for every contract.
Favicon Sizes in 2026: What You Need, What to Skip
The five files that cover every browser in 2026, the legacy sizes you can delete, dark-mode tab fixes, and the caching gotcha that wastes afternoons.
How Much House Can I Afford? The 28/36 Rule in Practice
A worked example at $85,000: what 28/36 actually allows, the real monthly payment on a $340,000 house, where PMI lands, and the down payment trap.
How Much to Tip in the US: A Plain-English Guide
Restaurant servers get 18-20%, delivery drivers get more than you think, and the tablets are bluffing. My plain-English US tipping guide with real math.
Regex for Normal People: The 10 Symbols That Do 90 Percent of the Work
Ten symbols cover about 90% of everyday regex jobs. I show real find-and-replace examples, plus the situations where regex will genuinely make life worse.
Sales Tax vs VAT: Why the Shelf Price Lies in One Country and Not the Other
US shelf prices add tax at the register while UK prices bake VAT in. I walk through why, with worked examples for reversing both from any receipt.
Unix Timestamps Explained: Seconds, Milliseconds, and the Year 2038
Unix time is one number counting seconds since 1970. I cover seconds vs milliseconds, the 2038 problem, and the timestamp bug that cost me an afternoon.
BMI vs Body Fat Percentage: Which Number Matters?
What BMI can and cannot tell you, why muscular people flag as obese, and the numbers I actually track for fat loss instead of trusting either alone.
What Belongs in a Professional Email Signature
The four lines that earn their place, the image mistakes that break in Outlook, the legal lines UK companies must include, and why tables still win.
What Flesch-Kincaid Actually Measures and What to Aim For
The two readability formulas in plain English, realistic score targets by content type, and the places where the metric confidently lies to you.
UTM Parameters: A Naming Convention You Will Stick To
The five UTM parameters explained, the lowercase rule that saves GA4 reports, and the naming system I adopted after wrecking six months of data.
AI Tokens Explained: Why Your Bill Ignores Word Count
What a token actually is, why code and non-English text cost more, and the napkin math I now use to estimate AI API costs before shipping anything.
How to Write Meta Titles and Descriptions That Get Clicks
Pixel limits beat character counts, title patterns that earn clicks, and why Google rewrites weak titles. What I changed after mine got mangled.
Open Graph Image Sizes That Actually Work in 2026
The 1200x630 rule, the safe zone that survives every crop, and the per-platform quirks that cost me an afternoon each. My exact checklist inside.
How to compress an image to an exact file size
Portals that demand under 200 KB, forms that reject your photo, and the quality setting that will not tell you what it produces. Here is how to hit a number reliably.
How many hashtags to use on each platform
Thirty is normal on Instagram and looks like spam on X. Three is the whole strategy on YouTube. Here is the real number for each platform, and why they differ so much.
Why Excel ruins your CSV files, and how to stop it
Leading zeros vanish, long numbers turn into scientific notation, and dates get rewritten. Excel is not broken. It is guessing, and here is how to stop it guessing.
Margin vs markup: the mistake that quietly costs you money
A 50 percent markup is a 33 percent margin. Mixing the two up is the most expensive arithmetic error in small business, and almost everybody makes it at least once.
How to merge PDFs without uploading them anywhere
Most free PDF tools send your file to a server. For contracts, bank statements and medical records that is a real decision. Here is how to do the same job in your browser.