H3 parent cell

Model: H3 v4 hierarchy (h3o 0.11)

Accuracy: Identical to H3 C

When to use this: Use this when rolling detail up: the coarser cell that contains a cell, and the child position it occupies within that parent. It is how a fine aggregation is summarized, and how cells at mixed resolutions are compared on common ground. The child position it reports is what lets you tell siblings apart within a parent, which matters when building keys or checking that a set is complete before compacting it.

Limitations: H3's hierarchy is approximate: a child is not wholly inside its parent, so rolling up near boundaries moves a little area between parents. The parent's resolution must be coarser than the cell's, and a chain of parents accumulates that approximation. Because the hierarchy is approximate, a point near a cell boundary can belong to a parent that does not contain its own cell's center, so rolled-up counts shift slightly between levels. Resolution 0 has no parent.

Worked example: Parent of 892a8471487ffff at resolution 5. Source: add-spatial-indexing-and-raster scenario: 852a8473fffffff.

Review: Not yet independently reviewed by a GIS professional.

Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.0.0, core 0.1.0. See this tool in the verification report.

Changes

• 2026-09-19, changed: Eight more H3 tools are stable: the cell inspector, grid ring, grid path, parent, children, compact, uncompact, and edges. On 300 cells at every resolution, one in eight a pentagon, they match H3 C exactly, including every path H3 C refuses; cell areas agree to 2e-8 relative even at resolution 15. Results are unchanged. Changelog

Checked against: 20 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

• H3: A Hexagonal Hierarchical Geospatial Indexing System (API reference v4), Uber Technologies and the H3 contributors, H3 4.x documentation. Indexing, inspection, traversal, hierarchy, directed edges, vertexes, and resolution tables. Read free.
• h3o: a Rust implementation of H3, Hydronium Labs, 0.11.0 (tested against H3 C). CellIndex, LatLng, Resolution. Read free.

Terms

H3: H3 hexagonal hierarchical index

A global grid of hexagons (and 12 pentagons) at 16 resolutions, each cell about one-seventh the area of its parent, named by a 15-character index. Source: H3 hexagonal index