Comparisons
When the question is “which one should I use?”, you don’t want a tool — you want a recommendation. Each comparison lays out the underlying trade-off, walks through worked examples, and finishes with a clear answer for the typical case.
Celsius vs Fahrenheit: why two scales survived
Where each came from, the conversion formula's algebra, and the one rare context where Fahrenheit's resolution is actually useful.
Kilograms vs pounds: the 2.20462 you can never quite remember
The factor, the history, the mental shortcut, and the two cases where the difference matters.
PNG vs JPG: when to use which
Lossless vs lossy, alpha vs none, file-size trade-offs.
Wei vs Gwei: which unit to use when
Two Ethereum subunits, both denominated in powers of ten. Where each is the right choice.
UTC vs GMT: are they the same?
Same clock on the wall. Different definition behind it. Here's the distinction that matters.
RGB vs CMYK: additive vs subtractive, screens vs print
Different mediums, different math, different gamuts. Why brilliant orange on monitor turns muddy in print.
SHA-256 vs MD5: never use MD5 for security
MD5 has been cryptographically broken since 2004. Why it persists, where it's acceptable, what to use instead.
Bitcoin vs Ethereum: different goals, different tradeoffs
Smart contracts vs digital gold, proof-of-stake vs proof-of-work, programmability vs scarcity.
JPG vs WebP: 25% smaller files at the same quality
WebP beats JPG on file size at equivalent visual quality. The catch (browser support) is mostly gone.
BMI vs body fat percentage: which actually tells you something useful?
BMI is fast and free; body fat is informative but harder to measure. When each is the right tool.
US cup vs UK cup: the kitchen measurement that varies by country
A US cup is 237 ml. A UK cup is 284 ml. An Australian cup is 250 ml. The 20% gap that ruins recipes.