ToolHQ Blog
Guides, tutorials, and tips for getting the most out of free online tools. 81 articles.
81 articles — page 3 of 4
A Video File Has Two Tracks. Converting to MP3 Keeps One.
Video files store audio and video as separate independent tracks. Here is how container formats work and why extracting audio keeps 95 percent of the content in 5 percent of the space.
Images Are 60 Percent of the Average Web Page. Here Is Which JPEG Quality Setting You Should Be Using.
Images carry over 60% of a typical web page's byte weight. Here is what JPEG quality settings actually control and what research says about the right setting for web use.
Your Phone Takes JPEGs. Your Accountant Needs PDFs. Here Is the Gap.
Why freelancers and independent contractors convert JPG photos to PDF for tax records, administrative submissions, and document filing workflows.
At 11:59:60 PM, Servers Around the World Panicked. The Single Extra Second That Crashed Reddit in 2012.
On July 1, 2012, a leap second in UTC caused a Linux kernel bug that took down Reddit, Mozilla, LinkedIn, and airline reservation systems for hours.
50% Off Plus 30% Off Is Not 80% Off. Here Is the Math Retailers Count On You Missing.
Sequential percentage discounts compound rather than add. A 50% sale plus a 30% coupon gives 65% off, not 80%. Here's the math behind stacked discounts and anchor pricing.
The Committee That Built an Unkillable Format: JPEG's 36-Year Run
JPEG was designed in 1986 by a committee from IBM, AT&T, and Canon. Here's the math, the patent wars, and why nothing has replaced it in 36 years.
The White Box Problem: What PNG Transparency Becomes in a JPG
Why converting a PNG with transparency to JPG creates a white box, and what to do instead. Covers JPEG's YCbCr model, alpha channels, and format tradeoffs.
She Recorded 18 Podcast Interviews as MP4. She Never Needed the Video.
Recording software captures video even when you only need audio. Here is why converting MP4 to MP3 cuts file size by over 90 percent with no loss to the audience.
URL Shorteners Were Built for Newsgroups. Twitter Nearly Killed Them. Then Twitter Made Them Indispensable.
TinyURL launched in 2002 to fix broken newsgroup URLs. Twitter's 140-character limit in 2009 made shorteners essential. Bitly links hit 2.1 billion clicks in November 2009.
The 300 DPI Rule Is Right for the Wrong Reasons
Most people misunderstand DPI in digital images. Here's what resolution actually means, how to calculate the pixels you need for print, and why the DPI number is just metadata.
Amazon Requires Pure White Backgrounds for Product Photos. Here Is What Enforcing That Standard Actually Costs Small Sellers.
Amazon mandates pure white (RGB 255,255,255) backgrounds for product photos or listings get suppressed. Here is how AI background removal changes the economics.
127 Pages from Four Different Sources, Merged Before Midnight
What PDF merging actually does technically, why the quality of mergers varies, and the real-world scenarios where assembling a single clean PDF is non-negotiable.
The Lawyer Sent the Contract as DOCX. Opposing Counsel Could Read Every Deleted Clause.
Word documents carry tracked changes, author names, and revision history that are invisible in the document but accessible in the file. Converting to PDF removes all of it.
Why the United States Still Uses Fahrenheit: A Scale Set by One Man's Body Temperature in 1724
Daniel Fahrenheit calibrated his scale against brine and body heat in 1714. Three centuries later, the US still uses it. Here is why switching proved impossible.
The Internet Ran Out of Addresses on February 3, 2011. Nobody Noticed Because of a Workaround Invented in 1994.
IPv4 addresses ran out in 2011. Network Address Translation has been hiding this from most users since 1994. The history of IP address exhaustion and what it means for your IP address.
QR Codes Are Not Just Fancy Barcodes. Here Is How They Actually Work.
QR codes use finder patterns, Reed-Solomon error correction, and mask patterns to encode thousands of characters readably from any angle. Here's how the system works.
Passphrases vs. Random Passwords: NIST Changed the Rules. Here Are the Real Tradeoffs.
In 2017 NIST scrapped complexity rules and raised a new question: passphrases or random strings? Here's how the entropy math actually works and when each wins.
PDF Compression: What the Bytes Actually Are (and Where They Go)
A PDF isn't a single file -- it's a container with separate compression per object. Here's what shrinks, what gets lost, and why that 47 MB deck becomes 4 MB.
Quintilian Assigned Paraphrase as Homework in the First Century. The Practice Has Not Aged Well.
Quintilian used paraphrase as a cognitive test in 1st century Rome. Two thousand years later, plagiarism detection exposed its limits. Here's what changed and why it matters.
The 40%-Off Sale Plus 20%-Off Coupon Is Not 60% Off. Here Is the Math.
Sequential percentage discounts compound rather than add. Percentage points differ from percentages. Here's the math behind three commonly confused percentage calculations.
Calculating Your Age Should Take One Second. Here Is Why It Sometimes Takes a Lawyer.
South Korea had two official age systems until 2023. Leap day birthdays require legal conventions. Time zones affect when legal thresholds are crossed. Age is more complicated than arithmetic.
Calorie Calculators Give You the Wrong Number. Here Is Why That Still Helps.
The Mifflin-St Jeor equation has a 200-calorie standard error. Gut microbiomes affect caloric absorption. Calorie calculators are approximations — here's how to use them correctly.
The First Grammar Checker Did Not Check Grammar
From Grammatik in 1981 to modern statistical models, grammar checkers evolved from style flaggers into AI tools. Here's how they actually work today and where they still fall short.
Douglas Crockford Wrote the JSON Spec on One Page. The Trailing Comma Has Been Breaking Things Ever Since.
JSON was invented in 2001 to solve one specific problem. Its strictest rules, no comments, no trailing commas, cause the most errors. Here is the full story.