diff --git a/.github/workflows/pr-size-labeler.yml b/.github/workflows/pr-size-labeler.yml
new file mode 100644
index 000000000..bc4d52c6d
--- /dev/null
+++ b/.github/workflows/pr-size-labeler.yml
@@ -0,0 +1,58 @@
+name: PR Size Labeler
+
+on:
+  pull_request_target:
+    branches: main
+
+jobs:
+  label-size:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+      issues: write
+    steps:
+      - name: Calculate PR size and apply label
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const pr = context.payload.pull_request;
+            const totalChanges = pr.additions + pr.deletions;
+            
+            // Remove existing size labels
+            const labels = await github.rest.issues.listLabelsOnIssue({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.payload.pull_request.number
+            });
+            
+            for (const label of labels.data) {
+              if (label.name.startsWith('size/')) {
+                await github.rest.issues.removeLabel({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  issue_number: context.payload.pull_request.number,
+                  name: label.name
+                });
+              }
+            }
+            
+            // Determine and apply new size label
+            let sizeLabel;
+            if (totalChanges <= 20) sizeLabel = 'size/xs';
+            else if (totalChanges <= 100) sizeLabel = 'size/s';
+            else if (totalChanges <= 500) sizeLabel = 'size/m';
+            else if (totalChanges <= 1000) sizeLabel = 'size/l';
+            else {
+              sizeLabel = 'size/xl';
+            }
+            
+            await github.rest.issues.addLabels({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.payload.pull_request.number,
+              labels: [sizeLabel]
+            });
+
+            if (sizeLabel === 'size/xl') {
+              core.setFailed(`PR is too large (${totalChanges} lines). Please split into smaller PRs.`);
+            }