Should I tune to 440 or 442 Hz?
442 Hz is 7.9 cents above 440 and makes two beats a second against it. When the number matters, and when it does not.
How to tune a violin with your phone
Bow one string at a time and match 440.00, 293.66, 196.00 and 659.26 Hz. The full method, and which app to use.
What is the highest frequency you can hear by age?
Your hearing ceiling drops roughly 1,000 Hz every decade. What most people can still hear at 30, 40, 50 and 60, and how ...
What Light Is Best for Applying Makeup?
Neutral daylight near 6500 K with high colour rendering. What kelvin and Ra mean, and how to check a look under three to...
How to find someone's ring size without them knowing
A ring they already wear is the only thing you can actually measure. Here is how to read it in under a minute, and which...
Can a Phone App Test Your Eyesight Accurately?
A phone eye test can screen your distance vision but cannot diagnose. What the 20-foot clinical chart measures, and why ...
How to measure your ring size at home
Ring size is one number: the inner circumference of a band that fits. Here is how to get it at home to within a millimet...
How to measure PPFD with your phone
A phone can report PPFD and DLI, but only if you add a diffuser and tell it which lamp you are under. Here is the method...
Best Moon Phase for Astrophotography
Why the new moon wins, how the dark-sky window works, and what ruins more nights than the moon does.
How to Plant by the Moon Phases
The six-step lunar sowing method, what root and leaf days actually mean, and the evidence on whether any of it works.
How to Bates number a PDF on an iPhone
Stamp a prefix and sequential number on every page from your phone: the court settings that matter, why printing to PDF ...
How to Sign a PDF on iPhone Without Printing It
Sign a PDF on an iPhone with no printer, no account and no subscription - plus what makes a phone signature legally hold...
How to Train a Dog Recall With a Whistle in 21 Days
A 21-day plan for teaching a dog to come back to one fixed whistle tone, with the numbers behind every step.
How to find the right dog whistle frequency for your dog
Most dogs answer best between 5,400 and 12,800 Hz. Here is how to find your own dog's pitch.
What Is the Difference Between Increment and Delay on a Chess Clock?
Increment adds time to your clock; delay only postpones the countdown. What FIDE actually says, how byo-yomi differs, an...
How to make your iPhone read an EPUB out loud
Most EPUB files carry no narration, so the phone has to generate the voice. Here is the offline route, and how it differ...
How to open FB2 and MOBI files on an iPhone
FB2, MOBI and AZW3 have no registered media type, so a stock iPhone will not open them. Here is the import-and-convert r...
How to sort laundry into loads that will not ruin each other
Sort by care label, not by colour: three passes through the basket, the symbols that decide the piles, and an offline An...
How to read a laundry care label with your phone camera
Flatten the label, find daylight, and let an offline Android scanner turn the pictograms into sentences. All 44 ISO care...
How to put a birthday countdown widget on the iPhone Lock Screen
The Lock Screen widget row is edited from the Lock Screen, not Settings. Here are the exact steps, the accessory sizes, ...