diff --git a/packages/block-library/src/buttons/style.scss b/packages/block-library/src/buttons/style.scss
index 8492553bd50b8..e563f3957f374 100644
--- a/packages/block-library/src/buttons/style.scss
+++ b/packages/block-library/src/buttons/style.scss
@@ -2,6 +2,8 @@
 $blocks-block__margin: 0.5em;
 
 .wp-block-buttons {
+	// This block has customizable padding, border-box makes that more predictable.
+	box-sizing: border-box;
 
 	&.is-vertical {
 		flex-direction: column;