Practical guides, how-tos and comparisons to get the most out of our free online tools.
FIGO puts a normal cycle at 24 to 38 days; ACOG's older range is 21 to 35. Here is why two respected bodies give different numbers, how much variation is normal, and how cycles change after menarche and before menopause.
Sofia Nunes · 6 min read
The last resort when nothing can be compressed further. It works, and it has three sharp edges: the parts are useless on their own, the order is absolute, and the megabyte you set is not the megabyte the limit means.
Daniel Okonkwo · 7 min read
Plain text has no layout, so any converter has to invent one for you. Here is exactly which decisions this one makes — page, margins, font, line breaks — what it does with a tab and a long line, and what you have to add yourself before a note is worth keeping.
Daniel Okonkwo · 19 min read
A 100 percent grade is 45 degrees, not vertical. Percent is rise ÷ run × 100, the angle is the arctangent of the same fraction, and the two are not proportional. Here is the conversion table and the three ways people get it wrong.
Marco Bianchi · 8 min read
Length × width × average depth gives 21,065 gallons for a 32 by 16 ft pool. But average depth only means (shallow + deep) ÷ 2 when the floor slopes evenly, and most pools do not. Here is every shape formula and the correction.
Marco Bianchi · 8 min read
Three completely different faults hide behind the same sentence. One is the encoding, one is the separator, one is Excel guessing at types while it opens the file — and the fix for each is different. Here is how to tell them apart in five seconds.
Daniel Okonkwo · 19 min read
A 750 ml bottle pours five glasses, and guests average about one drink per hour. Everything else is arithmetic — here it is for 50 to 250 guests over three, four and five hours, with an honest range rather than a single number.
Marco Bianchi · 7 min read
A conventional wet brine is 5 to 6 percent salt by weight of the water and you pull the meat out on a timer. An equilibrium brine is 1 to 2 percent by weight of the meat and water together, and it cannot over-salt. Those are different numbers doing different jobs.
Marco Bianchi · 9 min read
Multiply fresh yeast by 0.4 for active dry and by 0.33 for instant. Those two numbers are the whole chart, they are King Arthur's professional figures, and they are approximate — here is how far, and what else changes when you swap.
Marco Bianchi · 7 min read
Move in on 18 October at $1,500 a month and you owe $677.42, $700.00 or $690.41 depending on which convention the lease uses. Agree on one before you sign, not after.
Camille Laurent · 6 min read
That tick at the edit point is not a flaw in the software. It is a step in the waveform, and a step is broadband energy — which is the definition of a click. Here is the arithmetic, measured, and the two places you can put a cut so it never happens.
Daniel Okonkwo · 18 min read
Folding diacritics is a normalisation step, and normalisation only works when the same function runs on the index and on the query. NFC against NFD with the code points shown, and the letters — ø, ł, ß, œ, ı — that survive the strip untouched.
Daniel Okonkwo · 15 min read