diff --git a/.github/workflows/crate-bloat.yml b/.github/workflows/crate-bloat.yml
new file mode 100644
index 00000000000..91c2e8333d1
--- /dev/null
+++ b/.github/workflows/crate-bloat.yml
@@ -0,0 +1,65 @@
+# Reports compiled machine-code (.text) size per Vortex crate as a sticky PR comment.
+# Builds the datafusion-bench binary on stable and attributes its .text back to
+# each first-party crate with cargo-bloat.
+
+name: Crate Binary Size
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+on: [pull_request]
+
+permissions:
+  contents: read
+  pull-requests: write  # for commenting on PRs
+
+jobs:
+  bloat:
+    name: Per-crate .text size
+    runs-on: ubuntu-latest
+    timeout-minutes: 90
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6
+
+      - uses: ./.github/actions/setup-rust
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install cargo-bloat
+        uses: taiki-e/cache-cargo-install-action@66c9585ef5ca780ee69399975a5e911f47905995
+        with:
+          tool: cargo-bloat
+
+      - name: Measure per-crate binary size vs develop
+        shell: bash
+        run: |
+          set -Eeu -o pipefail -x
+
+          bloat() {
+            cargo bloat --package datafusion-bench --bin datafusion-bench \
+              --release --crates -n 0 --message-format json
+          }
+
+          head_sha=$(git rev-parse HEAD)
+
+          # Measure the PR head.
+          bloat > bloat-head.json
+
+          # Measure develop on the same machine, reusing the target directory so
+          # only changed crates are rebuilt.
+          git fetch --no-tags --depth=1 origin develop
+          git checkout -f FETCH_HEAD
+          bloat > bloat-develop.json
+
+          # Restore the PR head and render with its copy of the script.
+          git checkout -f "$head_sha"
+          python3 scripts/crate-bloat.py bloat-head.json --base-file bloat-develop.json > comment.md
+          cat comment.md >> "$GITHUB_STEP_SUMMARY"
+
+      - name: Comment PR
+        if: github.event.pull_request.head.repo.fork == false
+        uses: thollander/actions-comment-pull-request@24bffb9b452ba05a4f3f77933840a6a841d1b32b  # v3
+        with:
+          file-path: comment.md
+          comment-tag: crate-bloat-comment
diff --git a/scripts/crate-bloat.py b/scripts/crate-bloat.py
new file mode 100644
index 00000000000..da764f78019
--- /dev/null
+++ b/scripts/crate-bloat.py
@@ -0,0 +1,141 @@
+#!/usr/bin/env python3
+# /// script
+# requires-python = ">=3.11"
+# dependencies = []
+# ///
+
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright the Vortex contributors
+
+"""Render per-crate compiled (.text) size as a collapsible markdown comment.
+
+Consumes the JSON produced by ``cargo bloat --crates --message-format json``
+for a linked binary, keeps only first-party workspace crates, and prints a
+single ``<details>`` block: the ``<summary>`` is a one-line Vortex total so the
+comment stays compact, and expanding it reveals the full per-crate breakdown of
+machine code attributed to each Vortex crate, with deltas against ``develop``
+when a base measurement is provided.
+"""
+
+import argparse
+import json
+import subprocess
+
+
+def fmt_size(size_bytes: int) -> str:
+    """Format a byte count using binary units."""
+    if abs(size_bytes) >= 1024**2:
+        return f"{size_bytes / 1024**2:.2f} MiB"
+    if abs(size_bytes) >= 1024:
+        return f"{size_bytes / 1024:.1f} KiB"
+    return f"{size_bytes} B"
+
+
+def fmt_delta(delta: int) -> str:
+    """Format a signed size delta, or an em dash when unchanged."""
+    if delta == 0:
+        return "—"
+    return f"{'+' if delta > 0 else '−'}{fmt_size(abs(delta))}"
+
+
+def fmt_pct(base: int, head: int) -> str:
+    """Format a percentage change, handling newly introduced crates."""
+    if base == 0:
+        return "new" if head > 0 else "—"
+    if head == base:
+        return "—"
+    pct = (head / base - 1) * 100
+    return f"{'+' if pct > 0 else '−'}{abs(pct):.1f}%"
+
+
+def workspace_crate_names(manifest_path: str) -> set[str]:
+    """Return the set of first-party crate names (as cargo-bloat reports them)."""
+    out = subprocess.run(
+        ["cargo", "metadata", "--no-deps", "--format-version", "1", "--manifest-path", manifest_path],
+        capture_output=True,
+        text=True,
+        check=True,
+    )
+    metadata = json.loads(out.stdout)
+    names: set[str] = set()
+    for pkg in metadata["packages"]:
+        names.add(pkg["name"].replace("-", "_"))
+        for target in pkg["targets"]:
+            names.add(target["name"].replace("-", "_"))
+    return names
+
+
+def crate_sizes(bloat_file: str, workspace: set[str]) -> dict[str, int]:
+    """Load a cargo-bloat JSON file and keep only first-party crate sizes."""
+    with open(bloat_file) as f:
+        bloat = json.load(f)
+    sizes = {c["name"]: c["size"] for c in bloat.get("crates", []) if c["name"] in workspace}
+    sizes["__text_section_size__"] = bloat.get("text-section-size", 0)
+    return sizes
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Render per-crate .text size as a markdown comment")
+    parser.add_argument("head_file", help="cargo-bloat --crates JSON for HEAD")
+    parser.add_argument("--base-file", default=None, help="cargo-bloat --crates JSON for develop")
+    parser.add_argument("--manifest-path", default="Cargo.toml", help="Workspace Cargo.toml")
+    parser.add_argument("--target-name", default="datafusion-bench", help="Binary the sizes are measured from")
+    args = parser.parse_args()
+
+    workspace = workspace_crate_names(args.manifest_path)
+    head = crate_sizes(args.head_file, workspace)
+    base = crate_sizes(args.base_file, workspace) if args.base_file else {}
+    have_base = bool(base)
+
+    total_text = head.pop("__text_section_size__", 0)
+    base.pop("__text_section_size__", 0)
+
+    crates = sorted(set(head) | set(base))
+    rows = [(c, base.get(c, 0), head.get(c, 0), head.get(c, 0) - base.get(c, 0)) for c in crates]
+
+    vortex_head = sum(h for _, _, h, _ in rows)
+    vortex_base = sum(b for _, b, _, _ in rows)
+    vortex_delta = vortex_head - vortex_base
+
+    # Largest movers first, then largest crates.
+    rows.sort(key=lambda r: (abs(r[3]), r[2]), reverse=True)
+
+    if have_base:
+        if vortex_delta == 0:
+            summary = f"no code size change ({args.target_name})"
+        else:
+            summary = f"code size change {fmt_pct(vortex_base, vortex_head)} ({args.target_name})"
+    else:
+        summary = f"code size {fmt_size(vortex_head)} ({args.target_name})"
+
+    # Nothing changed against develop: keep the comment to a single line.
+    if have_base and vortex_delta == 0:
+        print(summary)
+        return
+
+    print("<details>")
+    print(f"<summary>{summary}</summary>")
+    print("")
+    print("<br>")
+    print("")
+    if have_base:
+        print("| Crate | .text | Δ vs develop | % |")
+        print("|-------|------:|-------------:|--:|")
+        for name, b, h, d in rows:
+            print(f"| `{name}` | {fmt_size(h)} | {fmt_delta(d)} | {fmt_pct(b, h)} |")
+        print("")
+        print(f"**Vortex total:** {fmt_size(vortex_base)} → {fmt_size(vortex_head)} ({fmt_delta(vortex_delta)})")
+    else:
+        print("| Crate | .text | % of Vortex |")
+        print("|-------|------:|------------:|")
+        for name, _, h, _ in rows:
+            pct = f"{h / vortex_head * 100:.1f}%" if vortex_head else "—"
+            print(f"| `{name}` | {fmt_size(h)} | {pct} |")
+        print("")
+        print(f"**Vortex total:** {fmt_size(vortex_head)} of the {fmt_size(total_text)} binary `.text`")
+    print("")
+    print("</details>")
+
+
+if __name__ == "__main__":
+    main()