You do not need a special Chinese IME to write a few Pinyin syllables with marks. You need a way to put ā, á, ǎ, à on the vowel. For a whole page of characters, you should not type those marks at all. Generate them from the Chinese, then fix the words the library guessed wrong.
This page is for the short job: a caption, a worksheet line, a name on a slide.
Fastest option on this site
In the Pinyin Writer, type the syllable and a number: hao3 becomes hǎo. Use 5 when you want the dotted neutral-tone style the tool describes. This avoids installing keyboards and avoids the third-tone mark, which is the one operating systems hide.
The Writer is a spelling aid. It does not know whether you meant 好 or 号. You already chose the letters.
Windows
The US International keyboard and the built-in Pinyin IME can both produce marked vowels, but they take setup. US International uses dead keys: a quotation mark then a may become ä, which is the wrong mark for Pinyin. People lose a morning to that.
Windows also lets you insert Unicode characters from the emoji panel or Character Map. That is fine for one ǎ. It is not a writing method.
For a short caption, the Writer is less fiddly than adding a keyboard layout you will forget how to turn off.
If you already type Chinese with Microsoft Pinyin, you can sometimes find tone-marked vowels in the IME's punctuation or symbol views. Coverage varies by version. Do not build a classroom workflow on a menu that moves every update.
macOS
Press and hold a vowel in many apps to see accent choices. That works for á and à more easily than for the third-tone caron (ǎ). Some apps never show ǎ. That is why learners still like number input.
You can also enable the ABC Extended keyboard and use Option-key combinations. Teachers who write Pinyin daily sometimes do this. Occasional users usually should not.
Android and iPhone
Press and hold vowels on the system keyboard. Coverage varies by keyboard app. Gboard and Apple's keyboard both offer some accents; the third tone may still be missing, and ü can be buried.
If you write Pinyin often on a phone, install a keyboard that advertises Pinyin tone support, or keep using numbers and convert them at the desk.
Rules the marks themselves follow
Standard Pinyin places one mark on one vowel in the syllable. The usual priority is a, then o, then e, then the last of i/u/ü in the pair. You write hǎo, not haǒ; xiǎo, not xiaǒ. The Writer follows those rules when you type numbers. If you insert characters by hand, you can put the mark on the wrong letter and still look "almost right."
See tone marks vs tone numbers for when to skip marks entirely.
When you should not type marks at all
If you already have Chinese characters, skip typing and generate Pinyin from the text. That is the right tool for a story, a vocabulary list extracted from a file, or a spreadsheet column of names. Then proofread polyphones.
If you need Simplified and Traditional conversion, that is a different converter. Marks do not change 国 into 國.
Frequently asked questions
Why is ǎ so hard to type? Because many Western accent menus were built for European languages that do not use a caron on a.
Can I copy marks from a webpage and paste them? Yes, if the paste target keeps Unicode. Some old forms will strip them. Check the result.
Is there a standard Windows shortcut for ǎ? Not a single universal one that every machine shares. That is the problem the Writer exists to avoid.
Should students learn number input first? It is a practical bridge. They still need to recognize marked Pinyin in print.
Does the Writer work offline? It runs in the browser session as a client-side tool. You still need to open the page.