Guides

Some things you look up every single time. Screenshot shortcuts, shrinking an image, figuring out Korean VAT. These are the ones worth writing down once so you stop searching for them.

• Every screenshot shortcut on Windows and MacFour shortcuts on Windows, four on the Mac: region, full screen, where the files land, and what Windows 11 changed about PrtScn.
• Resize an image without installing anythingPixels and file size are different things. Width targets for common uses, and how to shrink an image in the browser without installing anything.
• Korean VAT: adding it, and taking it back outKorean VAT is 10%: multiply by 1.1 to add it, divide by 1.1 to take it out, divide by 11 for the tax alone. Why subtracting gives the wrong answer.
• How many pixels is A4? Paper sizes × resolutionA4 is 2480 pixels at 300dpi and 595 at 72. A paper-size-by-resolution table, and how to choose between 72, 150 and 300.
• 16:9 height from any widthThe height for 16:9 is width times 9 divided by 16. Common size pairs for video and thumbnails, and how to flip the formula for other ratios.
• Fixing text that breaks when you paste itPasted text breaks for three reasons: curly quotes, doubled spaces, and carried-over line breaks. Where each comes from and how to clean them out.
• Color contrast: why 4.5:1 is the number to hitWhether text is readable is a number, not taste: 4.5:1 is the pass mark. What the ratio means and how to check your own colors against it.
• Counting characters: with spaces or without?Counting with or without spaces changes the number by 15 to 20%. Which counters use which rule, and the Korean byte limits that trip people up.
• Scheduling a call across time zones with KoreaKorea is UTC+9 with no daylight saving. How to convert a PST invite to Seoul time, and where DST switches and half-hour zones catch people.
• Why your card charges more than the exchange rateYour card charges about 2% more than the exchange rate says. Where the spread and the fees come in, worked through a real purchase.
• Inches, pounds, cups: the units that differ by countryInches and pounds are one multiplication; a cup depends on the country: 236.6mL in the US, 200mL in Korea. The conversions sorted by type.
• How many days left: and why the count is off by oneMarch 1 to March 10 is nine days and also ten. Whether today counts is the whole question. How countdowns, anniversaries and ages each count.
• JPG, PNG or WebP: which one should you save as?For the web, save WebP. For files you hand to someone, photos go to JPG and logos to PNG. How the three formats differ and where people pick wrong.
• A browser timer: what happens when you close the tab?A browser timer stops when you close the tab. What that means in practice, why the sound sometimes fails, and using one without installing anything.
• Notes saved in a browser: can they disappear?Notes saved in a browser live on this computer, not on a server. The few situations where they disappear, and what to do so they do not.
• Percent calculations go wrong in the same few placesHow to work out a percentage, why a rise and a fall use different base values, and what a percentage point is, with worked examples.
• You don't need an account to make a QR codeWhy QR codes are free to make, what paid QR sites are actually selling, and how to keep a printed code from dying on you one day.
• Special characters, without searching for them every timeCommon special characters collected so you can click to copy them, plus the keyboard routes on Windows and Mac for typing them yourself.
• Why the same emoji looks different on every phoneEmoji are sent as numbers, not pictures. Why the same emoji looks different on every phone, and why some arrive as empty boxes.
• Lunch bet: which picker do you reach for?Ladder draw, wheel, shuffled order, coin, dice. Which random picker fits what you are picking, from lunch bets to presentation order.
• Excel formulas, found by function nameAbout twenty functions cover almost everything. Search by function name — VLOOKUP, SUMIF, TRIM — to find the one you need, plus why VLOOKUP throws #N/
• Renaming a folder full of files at onceApply find-and-replace, numbering, and a prefix or suffix to a whole folder in that order. Preview first, undo in one click. Chrome and Edge only.
• Shrinking a batch of photos without uploading themResize and recompress a batch of photos right in the browser. Re-encoding never improves an image, so already-small photos are best left alone.
• Merging PDFs without uploading them anywhereCombine several PDFs into one and pull out specific pages, entirely in the browser. Password-protected PDFs can't be opened.
• Dressing up a screenshot with padding and a shadowWrap a screenshot in padding, a background, and a shadow before you post it. The original stays untouched — the look only gets baked in on export.
• Turning a review into a shareable cardPaste a review you already received and get back a square, wide, or tall card. It doesn't collect reviews for you.
• Printing name tags or certificates from a listPaste a list and it makes one card per person, up to 300 at a time, and hands them all back as a single PDF.
• Adding a background to a screen recordingRecord your screen, or drop in a clip you already have, and get back a version with a background, padding, and a shadow. The recording is put together
• Picking a video size that fits where you're postingVideo comes in three shapes: vertical 9:16, square 1:1, landscape 16:9. Where a clip is headed decides which one fits, and screen recordings default t
• Where captions get covered on vertical videoOn vertical video, the app's own interface (username, caption text, the like and comment buttons) sits over the footage at the top and bottom of the f
• Shooting one clip that works in three sizesReels wants vertical, the feed wants square, YouTube wants landscape. Getting the same clip to work in all three comes down to a few decisions made be
• Getting ready before you hit recordDecide what the clip needs to show, close out anything that might interrupt, and walk through the sequence once before recording for real. The mechani