Practical guides, how-tos and comparisons to get the most out of our free online tools.
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
The depth follows the job: a bare display, a planted tank whose roots need room, an under-gravel plate. Then comes the number people are unprepared for — substrate is what puts a filled tank past what a piece of furniture can hold. Plus why fine sand compacts and coarse gravel traps waste.
Marco Bianchi · 12 min read
Two to four inches, and the right end of that window depends on the material: bark takes 3, screened compost takes 1 to 2, and gravel takes 1. Here is the depth trade-off, the settling nobody buys for, and the bag conversion where the count goes wrong.
Marco Bianchi · 13 min read
The same 2,000 sq ft lawn at the same 1 lb of nitrogen per 1,000 sq ft takes 40 lb of a 5 percent blend or 4.3 lb of urea. Target nitrogen, not product — and read the bag count as shopping, not spreading.
Marco Bianchi · 12 min read
Four extensions, three of them the same box with different lids. Rename an XLSX to .zip and it opens — that single fact explains the whole family, and explains why XLS, which does not, is the one still causing trouble.
Daniel Okonkwo · 12 min read
The hourly rate is the small part. Minimum hours, the late-return surcharge, the ride home — and the question that changes the number most: casual help, or a declared employee? Six markets, named, with the thresholds that could be verified.
Camille Laurent · 12 min read
The same tank needs a 100 W heater in a warm flat and 300 W in an unheated room. The variable is the gap between the water and the room, which most rules of thumb drop entirely. Plus why two smaller heaters beat one big one, and where this calculator's recommendation stops being trustworthy.
Marco Bianchi · 12 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
A normal medium load in a high-efficiency machine works out at 37 ml. Load size swings that threefold; water hardness only 1.28-fold — and the tool's hardness input carries no units at all. Here are the scales and the conversions it leaves out.
Marco Bianchi · 12 min read
A local two-bedroom move estimates at $954–$1,347. Four boxes ticked on a three-bedroom move — peak week, full packing, two flights, full-value cover — take it from $1,730 to $3,162. Quotes differ on exclusions, not on price.
Camille Laurent · 12 min read
A two-bedroom home comes out at 56 boxes: 14 small, 21 medium, 12 large, 4 wardrobe, 5 dish. The total is the least useful number on the page — here is why the split matters, and what the count leaves out.
Marco Bianchi · 11 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