437 in this format. Showing the 48 most recent.
The same 12.7 kg puppy at sixteen weeks predicts a 21.9 kg adult if it is a small breed and 38.5 kg if it is a giant one. The arithmetic is trivial; the class you pick is worth seventy-six per cent.
Lena Hoffmann · 6 min read
Roll a 50 mm cone 80 mm tall and its pattern is a 190.8° slice of a 94 mm circle. Flatten a nearly cylindrical lampshade and the pattern radius runs to 839 mm — the shallower the taper, the further away the apex.
Lena Hoffmann · 6 min read
At 1 %, a hundred attempts give you 63.4 % — not certainty. Ninety per cent takes 230 attempts and ninety-nine takes 459, and more than a third of players are still empty-handed at a hundred.
Lena Hoffmann · 4 min read
Deduplication compares whole rows exactly, cell type included. Five identical-looking rows came out as three, because one held a number, one a string and one a string with a leading space.
Daniel Okonkwo · 4 min read
A spreadsheet file stores both the formula and the last answer Excel computed. Stripping the formula leaves the stored answer — and leaves a blank wherever the file never carried one.
Daniel Okonkwo · 4 min read
Venus never gets more than 47.2° from the Sun, so it is always within two signs of your Sun sign. Over 10,248 dates from 1966 to 2026 it lands in the same sign as the Sun barely a quarter of the time.
Antonio Delgado · 4 min read
A pattern asks for length and a shop sells weight. 400 yards of DK is 182 g and two balls; 400 yards of fingering is 100 g and one. The bridge is a single number on the label, and reading it wrong is the reason projects run out.
Antonio Delgado · 5 min read
The same 100 × 120 chart finishes 23 cm wide on 11-count and 11.5 cm wide on 22-count — twice the width, four times the area, from one number on the fabric label.
Antonio Delgado · 5 min read
Three nines sounds like a promise until you divide it into minutes. What 99.9 % buys per year, per month, per week and per day; why the measurement window matters far more than the extra nine; and the two different months this tool uses for the same slug.
Daniel Okonkwo · 10 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 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
Lumens are what a lamp emits; lux is what lands on a surface. You cannot convert one to the other without an area, or without a distance and a beam angle. Anything that offers you a bare conversion factor is selling you a fiction.
Lena Hoffmann · 11 min read
Sixty-three days is measured from ovulation, not from the mating. Counted from a mating date the same pregnancy spreads over two weeks, because sperm survive for days and a bitch is often mated more than once. What the calculator does with that, and where its window stops four days early.
Marco Bianchi · 11 min read
Resting energy scales with weight to the power 0.75, not linearly, which is why a chart that doubles the food for a cat twice the weight is 83 kcal a day over. Neutered against intact, indoor against outdoor, and the boundary the arithmetic must not cross.
Marco Bianchi · 11 min read
Every stocking calculator implements a length-per-volume rule, and waste output scales with body mass, not length. A fish twice as long makes nearly five times the ammonia. Run through the tool's five methods, the same tank comes back holding anywhere from 6 to 12 fish.
Marco Bianchi · 13 min read
Vout = Vin·R2/(R1+R2) is only true when nothing is connected to the output. Draw current and the voltage collapses, by an amount that follows one exact law. Here is that law, the ten-times rule checked against it, and why a lower-resistance divider costs you power forever.
Lena Hoffmann · 15 min read
Series adds, parallel adds reciprocals — that part is easy. The parts that catch people: which member dominates the answer, why two 5 % resistors in parallel are still 5 %, and why the smallest resistor in a parallel pair takes the largest share of the power.
Lena Hoffmann · 15 min read
The 40 % limit for three or more conductors is not about whether they physically fit. It is about heat and about pulling them in without stripping the insulation — and the moment you use that space, the code takes current away from every conductor in the pipe.
Marco Bianchi · 17 min read
Measured, not asserted: 90 short real phrases across six languages, none declined and 68 right — 76%, falling to 64% under sixteen letters. Four of the wrong answers came back at 100% confidence.
Daniel Okonkwo · 16 min read
Torque does not hold a joint together — preload does, and torque is a poor proxy for it. Here is where 90 % of your effort goes, what the K-factor really is, and why the same 37.84 N·m gives anything from 12.61 kN to 37.84 kN of clamping force.
Marco Bianchi · 14 min read
01/02/2026 is 1 February in most of Europe and 2 January in the United States, and nothing in the string says which. ISO 8601 fixes that, sorts as text, and stops being ISO 8601 in four specific places that RFC 3339 rejects.
Daniel Okonkwo · 16 min read
Scaling until the loudest sample hits a ceiling barely changes how loud something sounds. Measuring in LUFS does. This tool measures — in two passes, correctly — and then prints a result it never verified, which on ordinary material can be well over a decibel adrift.
Daniel Okonkwo · 14 min read
One emoji is 1 character, or 7, or 11, or 25, depending on who is counting. Which one your form, your database and your SMS gateway mean — and a one-paste test that tells you which you are facing.
Daniel Okonkwo · 13 min read
English title case has three different cutoffs depending on the style guide. French, Spanish, Portuguese and Italian have none at all. German capitalises every noun. The tool knows about none of this — here is exactly what it does.
Daniel Okonkwo · 13 min read
A URL at the end of a sentence keeps the full stop; an email address at the end of the same sentence does not. An accented first name in an address comes back truncated. Every case here was run through the tools and the exact output is reported.
Daniel Okonkwo · 14 min read
There are two completely different ways to turn a video, and only one of them touches the picture. This tool takes the slow, lossy, universal road — and there is a good chance your sideways phone clip does not need it at all.
Daniel Okonkwo · 11 min read
Two lines that look identical are often not identical. Case, a trailing space, a no-break space and two different encodings of the same accented letter were each run through the duplicate finder, and it reported no duplicates for three of the four.
Daniel Okonkwo · 11 min read
Luhn is a checksum for catching typos, patented in 1960, and that is its entire job. A number that passes it tells you nothing about any account. For testing a payment integration you need your processor's published numbers, not a generated one.
Daniel Okonkwo · 15 min read
RFC 8259 requires exactly three things to be escaped inside a JSON string. Everything else is optional. The one that actually breaks pipelines is a lone surrogate — legal in JSON text, impossible in UTF-8, and silently replaced the moment your data is written out.
Daniel Okonkwo · 13 min read
The same company, the same year, reads 1.02×, 1.52× or 2.56× depending on where rent is put and whether principal is grossed up for tax. Two of those pass a 1.25 covenant and one does not.
Camille Laurent · 17 min read
A missing quarter in France costs you twice over, through two separate mechanisms that most explanations mention only one of. A German point is a single arithmetic step and much easier to price. Both are computable, and the 2026 figures changed more than usual.
Camille Laurent · 14 min read
The 183-day rule is the most repeated and least understood sentence in cross-border work. It comes from one article of one model treaty, it has three conditions and not one, and it decides nothing at all about social security, payroll or your employer's exposure. Here is what each rule actually tests.
Camille Laurent · 16 min read
Net sales divided by net fixed assets is one of the easiest ratios to compute and one of the least comparable. The same retailer scored 10× before the lease standard and 1.39× after it — same shops, same sales, same year.
Camille Laurent · 13 min read
France caps the total cost of a mortgage at one third above the market average, insurance included. Portugal caps the monthly repayment at a share of net income — and on 1 August 2026 it cut that share from 50 % to 45 %. Neither ceiling means what the headline percentage suggests.
Camille Laurent · 13 min read
Return on assets, return on net assets and return on capital employed are one family with two moving parts. On the same balance sheet they read 8.3%, 10.2% and 15.6% — and the two steps between them are exactly the two decisions you are making.
Camille Laurent · 13 min read
Why the reader's language decides the delimiter, what the converter does to the quoting when you switch, what the sep= first line really is, and the count of quoted cells on the same export written five ways.
Daniel Okonkwo · 15 min read
The heating bill is real and it is small — about a fifteenth of the fuel a car commuter stops burning. The balance only goes negative in three identifiable cases, and one of them is a season ticket. Priced from Eurostat energy data, with the German tax system pushing the other way.
Camille Laurent · 17 min read
The numerator is on your own invoices. The denominator is the problem, and the usual fixes make it worse. How to build one from what you can actually observe, why the served market and the total market give answers a hundred times apart, and why a share on the wrong denominator is worse than no number at all.
Camille Laurent · 16 min read
Two of these three things are usually not in the law at all, and the one that is works completely differently in each country. Here is what a statute actually guarantees, what comes from a collective agreement instead, and why an Italian leaving voluntarily walks away with more than a French employee who was dismissed.
Camille Laurent · 13 min read
The same document has opposite default effects on either side of the Rhine: in France a signed fixed-price quotation forbids any increase, in Germany an estimate carries no guarantee of correctness unless the contractor took one on. Plus the particulars that are general, the ones that are trade rules, and why a free quotation is not free.
Camille Laurent · 8 min read
Nobody negotiates a company car as a pay cut, but that is what the tax treatment makes it. Three countries value the same car by three completely different methods, one of them changed in 2025 in a way that nearly doubled the figure, and in all three an electric car is taxed at a fraction of the same vehicle with an engine.
Camille Laurent · 13 min read
Two documents that differ only in how many children exist produce two different JSON shapes, and no converter can tell them apart without a schema. Plus what this one really does with attributes, mixed content and whitespace — and the one thing it still cannot record.
Daniel Okonkwo · 15 min read
Four European countries, four different answers to the same question: at what point does a small business stop being treated as small? The thresholds matter less than the clock attached to them — some bite the day you cross, others wait for January.
Camille Laurent · 13 min read