Practical guides, how-tos and comparisons to get the most out of our free online tools.
Knot strength is quoted as a percentage of the line's rated breaking strain, and the percentages in circulation come from tests nobody agrees on. What the calculator on this page really stores, what one peer-reviewed measurement actually found, where a line breaks and why, and how to match a knot to its job.
Antonio Delgado · 13 min read
The generator's random source audited line by line, what SAE actually removes, why transition mode gives most of it back, and the thing every guest-network guide leaves out.
Daniel Okonkwo · 13 min read
Entropy prices one attack: offline guessing against a stolen hash. Above roughly 90 bits the number stops deciding anything — and the meter on this site under-reported a random 20-character password in 300 draws out of 300.
Daniel Okonkwo · 12 min read
A JPEG can carry six separate metadata blocks, not one. We built a file holding all of them — coordinates, camera serial, a hidden thumbnail, XMP, IPTC, a comment — pushed it through the cleaner, and read the output byte by byte to see what survived.
Daniel Okonkwo · 14 min read
Golden hour runs from +6° to −4° of solar elevation and blue hour from −4° to −6°, which is why it lasts forty minutes at the equator, over an hour at mid-latitudes, and above 72.6° in June does not happen at all. The thresholds this calculator uses, checked against its own output.
Daniel Okonkwo · 12 min read
Counting back and counting forward are two different sums, and they disagree by a year on the day itself. What this calculator does with 29 February, what other date libraries do, and where the traditional and modern gift lists actually come from.
Antonio Delgado · 11 min read
0800 is not “eight o'clock” and not “08:00” — it is “zero eight hundred”, with a zone letter on the end. The four digits, the spoken form, midnight at 0000, the argument about 2400, and the reason 12-hour notation cannot settle noon.
Daniel Okonkwo · 11 min read
Magnus–Tetens with the Alduchov–Eskridge coefficients, 17.625 and 243.04. Why an absolute number beats relative humidity for judging comfort, what temperature a window has to reach before it runs, and the one input the calculator does not check.
Lena Hoffmann · 11 min read
The calculator runs the 2001 index, not the 1945 one, and refuses to answer above 50 °F or under 3 mph. Here is what its number is a model of — bare skin, in shade, walking — and the two things it says nothing about: a clothed body, and a parked car.
Lena Hoffmann · 12 min read
The addition is the easy half. Turning balances into the fewest possible transfers is a different, and much harder, computation — and the tool's own note claims a minimum it does not deliver. Plus uneven shares, and why the awkwardness is ambiguity rather than money.
Camille Laurent · 11 min read
The number is large because it is a daily number multiplied by 260 or 365 — and the same arithmetic works on anything daily, which is the part worth keeping. With the home-brewing comparison done properly, and a plain statement of what the number is not.
Camille Laurent · 10 min read
The addition is trivial. What people miss is the annual plan billed once, the trial that converted, the conversion fee on a service billed abroad — and the break-even month that decides whether a yearly plan was ever a saving.
Camille Laurent · 11 min read