diff --git a/update_zattrs.py b/update_zattrs.py
new file mode 100644
index 0000000..43ebf3d
--- /dev/null
+++ b/update_zattrs.py
@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+
+import argparse
+import json
+import os
+from pathlib import Path
+from typing import List, Dict, Any, Optional, Tuple
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        description="Update .zattrs multiscale levels by upsampling/downsampling from a reference level."
+    )
+    parser.add_argument(
+        "--upsample-factor",
+        type=float,
+        required=True,
+        help="Upsample factor between levels (e.g., 2 for 2x upsampling per level)."
+    )
+    parser.add_argument(
+        "zattrs_path",
+        type=Path,
+        help="Path to the .zattrs JSON file."
+    )
+    parser.add_argument(
+        "ome_zarr_dir",
+        type=Path,
+        nargs="?",
+        default=None,
+        help="(Optional) Path to the ome-zarr directory. If not given, will use the directory containing the .zattrs."
+    )
+    return parser.parse_args()
+
+def read_zattrs(zattrs_path: Path) -> Dict[str, Any]:
+    with open(zattrs_path, 'r') as f:
+        return json.load(f)
+
+def write_zattrs(zattrs_path: Path, zattrs: Dict[str, Any]):
+    with open(zattrs_path, 'w') as f:
+        json.dump(zattrs, f, indent=4)
+
+def get_reference_level(datasets: List[Dict[str, Any]]) -> Tuple[int, Dict[str, Any]]:
+    """
+    Returns the reference level (int) and the dataset entry.
+    Assumes 'path' is a string representing an integer.
+    """
+    assert datasets, "No datasets found in multiscales."
+    # Pick the first dataset as reference (by convention of example)
+    ref = datasets[0]
+    ref_level = int(ref["path"])
+    return ref_level, ref
+
+def get_existing_levels(ome_zarr_dir: Path) -> List[int]:
+    """
+    Returns a sorted list of integers for each group/array in the ome-zarr directory that is an integer name.
+    """
+    levels = []
+    for entry in os.listdir(ome_zarr_dir):
+        try:
+            lvl = int(entry)
+            if (ome_zarr_dir / entry).is_dir():
+                levels.append(lvl)
+        except ValueError:
+            continue
+    return sorted(levels)
+
+def update_scale_and_translation(ref_scale: List[float], ref_translation: List[float], ref_level: int, target_level: int, upsample_factor: float) -> Tuple[List[float], List[float]]:
+    """
+    Calculate new scale and translation for a given target_level using upsample_factor relative to reference.
+    """
+    factor = upsample_factor ** (ref_level - target_level)
+    new_scale = [v / factor for v in ref_scale]
+    new_translation = [v / factor for v in ref_translation]
+    return new_scale, new_translation
+
+def build_new_datasets(
+    levels: List[int],
+    ref_level: int,
+    ref_dataset: Dict[str, Any],
+    upsample_factor: float
+) -> List[Dict[str, Any]]:
+    """
+    Build new datasets list with coordinateTransformations updated for each level.
+    """
+    ref_scale = None
+    ref_translation = None
+    for trans in ref_dataset["coordinateTransformations"]:
+        if trans["type"] == "scale":
+            ref_scale = trans["scale"]
+        elif trans["type"] == "translation":
+            ref_translation = trans["translation"]
+    assert ref_scale is not None, "No scale transformation in reference dataset"
+    assert ref_translation is not None, "No translation transformation in reference dataset"
+    datasets = []
+    for lvl in levels:
+        scale, translation = update_scale_and_translation(ref_scale, ref_translation, ref_level, lvl, upsample_factor)
+        datasets.append({
+            "path": str(lvl),
+            "coordinateTransformations": [
+                {
+                    "type": "scale",
+                    "scale": scale
+                },
+                {
+                    "type": "translation",
+                    "translation": translation
+                }
+            ]
+        })
+    return datasets
+
+def main():
+    args = parse_args()
+
+    zattrs_path = args.zattrs_path
+    ome_zarr_dir = args.ome_zarr_dir or zattrs_path.parent
+
+    zattrs = read_zattrs(zattrs_path)
+    multiscale = zattrs["multiscales"][0]
+    datasets = multiscale["datasets"]
+    ref_level, ref_dataset = get_reference_level(datasets)
+
+    levels = get_existing_levels(ome_zarr_dir)
+    if not levels:
+        raise RuntimeError(f"No integer-named directories found in {ome_zarr_dir}")
+
+    # Build new datasets
+    new_datasets = build_new_datasets(
+        levels=levels,
+        ref_level=ref_level,
+        ref_dataset=ref_dataset,
+        upsample_factor=args.upsample_factor
+    )
+
+    # Overwrite datasets in zattrs
+    zattrs["multiscales"][0]["datasets"] = new_datasets
+
+    # Write back to .zattrs (or print, depending on design)
+    write_zattrs(zattrs_path, zattrs)
+    print(f"Updated .zattrs written to {zattrs_path}")
+
+if __name__ == "__main__":
+    main()