diff --git a/.changeset/cool-buckets-end.md b/.changeset/cool-buckets-end.md
new file mode 100644
index 00000000000..dad8c852f04
--- /dev/null
+++ b/.changeset/cool-buckets-end.md
@@ -0,0 +1,8 @@
+---
+'@primer/react': patch
+---
+
+- Corrects the math to calculate the width of AvatarStack containers.
+- Prevents `.pc-AvatarStackBody` from being removed from document flow by `position: absolute`. This isn't strictly necessary now that we're correctly setting the width of the stack, but it's an extra level of safety for preserving the correct layout.
+
+<!-- Changed components: AvatarStack -->
diff --git a/src/AvatarStack/AvatarStack.tsx b/src/AvatarStack/AvatarStack.tsx
index 2351eb5b588..880e6d52e37 100644
--- a/src/AvatarStack/AvatarStack.tsx
+++ b/src/AvatarStack/AvatarStack.tsx
@@ -19,26 +19,14 @@ const AvatarStackWrapper = styled.span<StyledAvatarStackWrapperProps>`
   --avatar-two-margin: calc(var(--avatar-stack-size) * -0.55);
   --avatar-three-margin: calc(var(--avatar-stack-size) * -0.85);
 
-  // this calc explained:
-  // 1. avatar size + the non-overlapping part of the second avatar
-  // 2. + the non-overlapping part of the second and third avatar
-  // 3. + the border widths of all previous avatars
-  --avatar-stack-three-plus-min-width: calc(
-    var(--avatar-stack-size) +
-      calc(
-        calc(var(--avatar-stack-size) + var(--avatar-two-margin)) +
-          calc(var(--avatar-stack-size) + var(--avatar-three-margin)) * 2
-      ) + calc(var(--avatar-border-width) * 3)
-  );
   display: flex;
   position: relative;
   height: var(--avatar-stack-size);
-  min-width: ${props => (props.count === 1 ? 'var(--avatar-stack-size)' : props.count === 2 ? '30px' : '38px')};
+  min-width: var(--avatar-stack-size);
 
   .pc-AvatarStackBody {
     display: flex;
     position: absolute;
-    width: var(--avatar-stack-three-plus-min-width);
   }
 
   .pc-AvatarItem {
@@ -92,8 +80,30 @@ const AvatarStackWrapper = styled.span<StyledAvatarStackWrapperProps>`
     );
   }
 
+  &.pc-AvatarStack--three {
+    // this calc explained:
+    // 1. avatar size + the non-overlapping part of the second avatar
+    // 2. + the non-overlapping part of the third avatar
+    min-width: calc(
+      var(--avatar-stack-size) +
+        calc(
+          calc(var(--avatar-stack-size) + var(--avatar-two-margin)) +
+            calc(var(--avatar-stack-size) + var(--avatar-three-margin))
+        )
+    );
+  }
+
   &.pc-AvatarStack--three-plus {
-    min-width: var(--avatar-stack-three-plus-min-width);
+    // this calc explained:
+    // 1. avatar size + the non-overlapping part of the second avatar
+    // 2. + the non-overlapping part of the third and fourth avatar
+    min-width: calc(
+      var(--avatar-stack-size) +
+        calc(
+          calc(var(--avatar-stack-size) + var(--avatar-two-margin)) +
+            calc(var(--avatar-stack-size) + var(--avatar-three-margin)) * 2
+        )
+    );
   }
 
   &.pc-AvatarStack--right {
@@ -150,6 +160,10 @@ const AvatarStackWrapper = styled.span<StyledAvatarStackWrapperProps>`
     }
   }
 
+  .pc-AvatarStack--disableExpand {
+    position: relative;
+  }
+
   ${sx};
 `
 const transformChildren = (children: React.ReactNode) => {
@@ -173,7 +187,8 @@ const AvatarStack = ({children, alignRight, disableExpand, size, sx: sxProp = de
   const count = React.Children.count(children)
   const wrapperClassNames = clsx({
     'pc-AvatarStack--two': count === 2,
-    'pc-AvatarStack--three-plus': count > 2,
+    'pc-AvatarStack--three': count === 3,
+    'pc-AvatarStack--three-plus': count > 3,
     'pc-AvatarStack--right': alignRight,
   })
   const bodyClassNames = clsx('pc-AvatarStackBody', {
diff --git a/src/__tests__/__snapshots__/AvatarStack.test.tsx.snap b/src/__tests__/__snapshots__/AvatarStack.test.tsx.snap
index 09ddd3157d5..8db11d1caf6 100644
--- a/src/__tests__/__snapshots__/AvatarStack.test.tsx.snap
+++ b/src/__tests__/__snapshots__/AvatarStack.test.tsx.snap
@@ -5,14 +5,13 @@ exports[`Avatar renders consistently 1`] = `
   --avatar-border-width: 1px;
   --avatar-two-margin: calc(var(--avatar-stack-size) * -0.55);
   --avatar-three-margin: calc(var(--avatar-stack-size) * -0.85);
-  --avatar-stack-three-plus-min-width: calc( var(--avatar-stack-size) + calc( calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + calc(var(--avatar-stack-size) + var(--avatar-three-margin)) * 2 ) + calc(var(--avatar-border-width) * 3) );
   display: -webkit-box;
   display: -webkit-flex;
   display: -ms-flexbox;
   display: flex;
   position: relative;
   height: var(--avatar-stack-size);
-  min-width: 38px;
+  min-width: var(--avatar-stack-size);
   --avatar-stack-size: 20px;
 }
 
@@ -22,7 +21,6 @@ exports[`Avatar renders consistently 1`] = `
   display: -ms-flexbox;
   display: flex;
   position: absolute;
-  width: var(--avatar-stack-three-plus-min-width);
 }
 
 .c0 .pc-AvatarItem {
@@ -72,8 +70,12 @@ exports[`Avatar renders consistently 1`] = `
   min-width: calc( var(--avatar-stack-size) + calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + var(--avatar-border-width) );
 }
 
+.c0.pc-AvatarStack--three {
+  min-width: calc( var(--avatar-stack-size) + calc( calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + calc(var(--avatar-stack-size) + var(--avatar-three-margin)) ) );
+}
+
 .c0.pc-AvatarStack--three-plus {
-  min-width: var(--avatar-stack-three-plus-min-width);
+  min-width: calc( var(--avatar-stack-size) + calc( calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + calc(var(--avatar-stack-size) + var(--avatar-three-margin)) * 2 ) );
 }
 
 .c0.pc-AvatarStack--right {
@@ -134,6 +136,10 @@ exports[`Avatar renders consistently 1`] = `
   margin-left: 0;
 }
 
+.c0 .pc-AvatarStack--disableExpand {
+  position: relative;
+}
+
 <span
   className="c0 pc-AvatarStack--three-plus"
 >
@@ -170,14 +176,13 @@ exports[`Avatar respects alignRight props 1`] = `
   --avatar-border-width: 1px;
   --avatar-two-margin: calc(var(--avatar-stack-size) * -0.55);
   --avatar-three-margin: calc(var(--avatar-stack-size) * -0.85);
-  --avatar-stack-three-plus-min-width: calc( var(--avatar-stack-size) + calc( calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + calc(var(--avatar-stack-size) + var(--avatar-three-margin)) * 2 ) + calc(var(--avatar-border-width) * 3) );
   display: -webkit-box;
   display: -webkit-flex;
   display: -ms-flexbox;
   display: flex;
   position: relative;
   height: var(--avatar-stack-size);
-  min-width: 38px;
+  min-width: var(--avatar-stack-size);
   --avatar-stack-size: 20px;
 }
 
@@ -187,7 +192,6 @@ exports[`Avatar respects alignRight props 1`] = `
   display: -ms-flexbox;
   display: flex;
   position: absolute;
-  width: var(--avatar-stack-three-plus-min-width);
 }
 
 .c0 .pc-AvatarItem {
@@ -237,8 +241,12 @@ exports[`Avatar respects alignRight props 1`] = `
   min-width: calc( var(--avatar-stack-size) + calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + var(--avatar-border-width) );
 }
 
+.c0.pc-AvatarStack--three {
+  min-width: calc( var(--avatar-stack-size) + calc( calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + calc(var(--avatar-stack-size) + var(--avatar-three-margin)) ) );
+}
+
 .c0.pc-AvatarStack--three-plus {
-  min-width: var(--avatar-stack-three-plus-min-width);
+  min-width: calc( var(--avatar-stack-size) + calc( calc(var(--avatar-stack-size) + var(--avatar-two-margin)) + calc(var(--avatar-stack-size) + var(--avatar-three-margin)) * 2 ) );
 }
 
 .c0.pc-AvatarStack--right {
@@ -299,6 +307,10 @@ exports[`Avatar respects alignRight props 1`] = `
   margin-left: 0;
 }
 
+.c0 .pc-AvatarStack--disableExpand {
+  position: relative;
+}
+
 <span
   className="c0 pc-AvatarStack--three-plus pc-AvatarStack--right"
 >