How to Double Space in Google Docs
Set double line spacing on selected text or a whole Google Doc from the Format menu or the toolbar button, and make it the default for new documents.
Google Docs opens new documents at 1.15 line spacing. Switching to double spacing takes one menu command, and it can apply to a selection, the whole document, or every document you create from now on.
Select the text
Click and drag over the paragraphs you want to change, or press Ctrl + A (Mac: Cmd + A) to select the entire document. Spacing applies to whole paragraphs, so placing the cursor inside a paragraph is enough for a single one.
Open Line & paragraph spacing
Click Format, hover Line & paragraph spacing, then click Double. The selected paragraphs spread out immediately.
Or use the toolbar button
Click the line spacing icon in the toolbar (an up and down arrow beside three horizontal lines, to the right of the alignment buttons) and pick Double from the dropdown. The same menu also offers Single, 1.15, 1.5, and Custom spacing for values such as 2.5.
Make double spacing the default
Set one paragraph to double spacing with the steps above and keep the cursor in it. Click Format, Paragraph styles, Normal text, Update 'Normal text' to match. Then click Format, Paragraph styles, Options, Save as my default styles. Every new document you create will open double spaced. Documents that already exist keep their current spacing.
Clear spacing carried in by pasted text
Text pasted from another document or a web page can bring its own spacing with it. Select the pasted section, press *Ctrl + * (Mac: **Cmd + **) to clear its formatting, then apply double spacing again from the Format menu.
Extra gaps between paragraphs. Double spacing sets the distance between lines, not between paragraphs. If paragraphs still look uneven, click Format, Line & paragraph spacing and choose Remove space after paragraph or Remove space before paragraph at the bottom of the menu. Those entries only show when there is space to remove.
In the mobile app. Tap the format icon (the A with lines beside it), open the Paragraph tab, and use the arrows next to Line spacing to step the value up to 2.