# @turf/isolines

> Generate contour lines from a grid of data.

Latest version **7.4.0** (published 2026-08-03) · MIT license · 0 weekly downloads

## Install

```sh
npm install @turf/isolines
pnpm add @turf/isolines
yarn add @turf/isolines
bun add @turf/isolines
```

## Health

**Score 80/100 (A)** — status: active.

Positive: has types; esm support; no vulnerabilities; has provenance; recently updated; high maintenance score; high quality score; popular repo.

Warnings: low downloads.

## Facts

| | |
|---|---|
| Version | 7.4.0 |
| Published | 2026-08-03 |
| First published | 2016-07-06 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Dependencies | 6 |
| Unpacked size | 82.2 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Provenance | attested (GitHub Actions) |
| GitHub stars | 10490 |
| Author | Turf Authors |
| Maintainers | rowanwins, tmcw, morganherlocker, tcql, mdfedderly, twelch, jamesmilneruk, morgan.herlocker |
| Keywords | turf, geojson, isolines, contours, elevation, topography |

## Links

- npm: https://www.npmjs.com/package/@turf/isolines
- Repository: https://github.com/Turfjs/turf
- Issues: https://github.com/Turfjs/turf/issues
- Funding: https://opencollective.com/turf
- npm.io page: https://npm.io/package/@turf/isolines

## Dependencies (6)

- [tslib](https://npm.io/package/tslib.md) ^2.8.1
- [@turf/bbox](https://npm.io/package/@turf/bbox.md) 7.4.0
- [@turf/meta](https://npm.io/package/@turf/meta.md) 7.4.0
- [@turf/helpers](https://npm.io/package/@turf/helpers.md) 7.4.0
- [@types/geojson](https://npm.io/package/@types/geojson.md) ^7946.0.10
- [@turf/invariant](https://npm.io/package/@turf/invariant.md) 7.4.0

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## Recent versions

- 7.4.0 (latest) — 2026-08-03
- 7.1.0-alpha.70 (prerelease) — 2024-08-09
- 3.5.2-alpha.d2c36ee7 (canary) — 2016-11-04
- 7.3.5 — 2026-04-19
- 7.3.4 — 2026-02-08
- 7.3.3 — 2026-01-28
- 7.3.2 — 2026-01-14
- 7.3.1 — 2025-11-27
- 7.3.0 — 2025-11-17
- 7.2.0 — 2024-12-29
- 7.1.0 — 2024-08-09
- 7.1.0-alpha.7 — 2024-06-25
- 7.0.0 — 2024-06-07
- 7.0.0-alpha.116 — 2024-05-07
- 7.0.0-alpha.115 — 2024-04-23
- … 55 more at https://npm.io/package/@turf/isolines/versions

## README

# @turf/isolines

<!-- Generated by documentation.js. Update this documentation by updating the source code. -->

## isolines

Takes a grid [FeatureCollection][1] of [Point][2] features with z-values and an array of
value breaks and generates [isolines][3].

### Parameters

*   `pointGrid` **[FeatureCollection][1]<[Point][2]>** input points - must be square or rectangular and already gridded. That is, to have consistent x and y dimensions and be at least 2x2 in size.
*   `breaks` **[Array][4]<[number][5]>** values of `zProperty` where to draw isolines
*   `options` **[Object][6]** Optional parameters (optional, default `{}`)

    *   `options.zProperty` **[string][7]** the property name in `points` from which z-values will be pulled (optional, default `'elevation'`)
    *   `options.commonProperties` **[Object][6]** GeoJSON properties passed to ALL isolines (optional, default `{}`)
    *   `options.breaksProperties` **[Array][4]<[Object][6]>** GeoJSON properties passed, in order, to the correspondent isoline;
        the breaks array will define the order in which the isolines are created (optional, default `[]`)

### Examples

```javascript
// create a grid of points with random z-values in their properties
var extent = [0, 30, 20, 50];
var cellWidth = 100;
var pointGrid = turf.pointGrid(extent, cellWidth, {units: 'miles'});

for (var i = 0; i < pointGrid.features.length; i++) {
    pointGrid.features[i].properties.temperature = Math.random() * 10;
}
var breaks = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

var lines = turf.isolines(pointGrid, breaks, {zProperty: 'temperature'});

//addToMap
var addToMap = [lines];
```

Returns **[FeatureCollection][1]<[MultiLineString][8]>** a FeatureCollection of [MultiLineString][8] features representing isolines

[1]: https://tools.ietf.org/html/rfc7946#section-3.3

[2]: https://tools.ietf.org/html/rfc7946#section-3.1.2

[3]: https://en.wikipedia.org/wiki/Contour_line

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array

[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

[8]: https://tools.ietf.org/html/rfc7946#section-3.1.5

<!-- This file is automatically generated. Please don't edit it directly. If you find an error, edit the source file of the module in question (likely index.js or index.ts), and re-run "yarn docs" from the root of the turf project. -->

---

This module is part of the [Turfjs project](https://turfjs.org/), an open source module collection dedicated to geographic algorithms. It is maintained in the [Turfjs/turf](https://github.com/Turfjs/turf) repository, where you can create PRs and issues.

### Installation

Install this single module individually:

```sh
$ npm install @turf/isolines
```

Or install the all-encompassing @turf/turf module that includes all modules as functions:

```sh
$ npm install @turf/turf
```

---
_Source: https://npm.io/package/@turf/isolines · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._