Every unit,
instantly.
The science and history behind units, measurements, and conversions.
✦ AI-powered — understands natural language
Why a Kettle Is 95% Efficient and a Power Station Is 45%
Why 20 MB of Files Takes Up 400 MB of Disk Space
100,000 files of 200 bytes each can consume 400 MB. Cluster sizes, slack space and filesystem metadata explain the gap between file size and space on disk.
EUR/USD or USD/EUR? Reading Currency Quotes Correctly
EUR/USD 1.0850 and USD/EUR 0.9217 are the same rate — but inverting a rounded quote costs you money. Base/quote conventions, cross rates and rounding rules explained.
Baker's Percentage: The Ratio That Makes Recipes Scalable
Baker's percentage turns any recipe into a scalable formula. Here's how hydration, salt and yeast ratios work — and how to convert a cup-based recipe into one.
Why One 18-Inch Pizza Beats Two 12-Inch Ones: Area Scaling
Doubling a dimension quadruples the area. That single rule explains pizza pricing, paint quantities, solar output, and why big rooms are cheaper to heat per square metre.
One Degree Off: How Small Angle Errors Compound Over Distance
A one-degree aiming error is invisible at arm's length and catastrophic at a kilometre. Here's the arc-length math behind MOA, mils, and surveying tolerances.
Why the Tola, Grain, and Troy Ounce Are Still in Active Use — Traditional Weight Units That Outlasted Metrication
The tola (11.664 grams) was never replaced in Indian and Gulf gold markets despite official metrication — because the South Asian gold trade embedded it in commercial practice so thoroughly that metric alternatives never displaced it. Here's why the grain (64.8 mg) persists in bullet weights and pharmacy, why a troy ounce (31.1g) and an avoirdupois ounce (28.3g) are different by 10% and both called "ounce," and why three different "tons" (short ton, metric tonne, long ton) each differ by enough to matter in commodity trading.
The Human Body Contains 42 Litres of Water — What Blood Volume, Lung Capacity, and Fluid Compartments Actually Mean Clinically
Losing 750 ml of blood (15% of total volume) is manageable — losing 1,500 ml is haemorrhagic shock, but rate matters as much as volume. Here's the ATLS haemorrhage classification by volume lost, the five lung volume subdivisions (TLC, VC, FRC, RV, tidal volume) and what each predicts in pulmonary disease, the 42-litre total body water distribution across intracellular and extracellular compartments, and why choosing the wrong IV fluid type (crystalloid vs colloid) worsens oedema while failing to restore plasma.
The Database That Runs Every Clock in Every App Almost Went Away in 2011 — The IANA Timezone Database Story
The IANA Time Zone Database — the source of timezone rules for Linux, macOS, Python, Java, and essentially every software platform — was briefly taken offline in 2011 due to a copyright lawsuit, creating a crisis for global software infrastructure. Here's how Samoa skipped an entire calendar day in December 2011, why Egypt and Morocco changed their DST rules with days of notice, the correct UTC-first database storage pattern, and why "UTC+1" is the wrong way to store a timezone.
UTC Is 37 Seconds Behind Atomic Time — Why Leap Seconds Exist, Why They Crash Software, and What Replaces Them After 2035
UTC and International Atomic Time (TAI) diverge by 37 seconds because Earth's rotation is slowing — atomic clocks keep perfect SI seconds, but solar noon would drift without periodic leap seconds inserted into UTC. Here's why the June 2012 leap second caused Reddit, Mozilla, and LinkedIn to go offline (a Linux kernel hrtimer bug), why GPS time is 18 seconds ahead of UTC, and why MiFID II's microsecond timestamp requirements create audit trail ambiguities around leap second boundaries.
Labs Have Reached 450 Picokelvin But Can Never Reach Zero — Absolute Zero, Superfluidity, and Why Quantum Computers Run Colder Than Deep Space
Absolute zero is unreachable because the third law of thermodynamics requires infinite cooling steps to extract the final increment of entropy — labs have reached 450 picokelvin, billions of times colder than outer space, but never 0 K. Here's what each temperature scale actually encodes (Fahrenheit's brine mixture zero point, Kelvin's thermodynamic basis), how Bose-Einstein condensates and superfluidity emerge near absolute zero, and why superconducting quantum computers must operate at 15 millikelvin — colder than anywhere in the observable universe.
Triple Your Speed, Use 27 Times More Power — The Physics of Aerodynamic Drag and Why High-Speed Transport Is So Hard
Aerodynamic drag scales with velocity squared and power with velocity cubed — triple your speed and you need 27 times more power to overcome drag. Here's why the Concorde burned 8× more fuel per passenger than a 747, why aircraft cruise at 35,000 feet to exploit thin air, why Hyperloop puts vehicles in a vacuum tube to sidestep the drag equation entirely, and the physics behind terminal velocity varying with altitude.
A Bathroom Scale Measures Force, Not Mass — Why Your "Weight" Changes in Elevators, on the Moon, and in Space
A bathroom scale measures the normal force the floor exerts back on you — not your mass directly — which is why the same scale would misread your weight on the Moon by a factor of 6. Here's why elevators make you feel heavier or lighter while your mass never changes, why astronauts are in continuous free-fall rather than "zero gravity," and why weightless objects still have full inertia and can still injure you.
