The caption is the highest-paid word real estate in your listing: five to ten short lines that sell the app, survive thumbnail size, and, since Apple's OCR update, double as search keywords. Most captions waste it on adjectives. Here are the formulas that reliably work, with the reasoning behind them.
The ground rules
Whatever the formula: one idea per slide, five to eight words maximum, readable at 200 pixels wide. If a caption needs a subtitle, it is two slides. And write captions before designing anything; they are the story, the screenshots are the proof (the full process).
Formula 1: verb + outcome
"Track every subscription", "Fall asleep in minutes", "Ship your invoice in 30 seconds". The workhorse formula: starts with what the user does, ends with what they get. It reads naturally, and because it is phrased the way people search, it doubles as keyword coverage now that Apple indexes caption text.
Formula 2: the number
"3 taps to a perfect scan", "Save 2 hours every week", "12 languages, one design". Numbers stop the eye at thumbnail size and make claims concrete. Use real numbers from your product; invented precision reads as marketing sludge.
Formula 3: the question
"Still doing invoices by hand?" A question names the pain and recruits the reader into answering it. Use at most one per set, usually on slide one or two, and follow it immediately with the slide that answers it.
Formula 4: the objection killer
"No account. No watermark. Free." The caption that removes the reason not to install. Best placed mid-set, once interest exists but doubts remain. List the top objection from your reviews and answer it in five words.
Formula 5: before / after
"From camera roll chaos to albums that build themselves." One line that contains the transformation. Works brilliantly when the screenshot actually shows the "after" state.
Sequencing the set
Slide 1: your strongest verb + outcome (it carries the most weight). Slides 2-3: the two next benefits, different formulas for rhythm. Mid-set: objection killer. End: social proof or recap. Then translate the whole sequence per market: localized captions convert dramatically better AND get indexed per storefront.
The short version
Verb + outcome as your default, a number when you have one, one question maximum, kill the top objection mid-set, and keep every line under eight words. Write them first, translate them per market, and let the screenshots prove what the captions promise.
