--- title: "How to style polygon outlines" description: "Draw a solid, dashed, or dotted outline around every polygon, and set its colour, transparency, and width. Works with every polygon style." sidebar: label: "Style polygon outlines" search: keywords: [border, stroke, boundary, edge, outline colour, outline width] --- An outline draws a line around the edge of every polygon on the layer. Use it to separate polygons that share a fill colour, such as countries in the same income group, or to show boundaries over a busy basemap. Open the layer's `Style` tab, set `Stroke` to `Solid`, `Dashed`, or `Dotted`, then pick a colour and a width. The outline works the same with every polygon style: one colour, categories, class breaks, or a continuous gradient. **[See it on an example map](https://mangomap-staging.com/examples-staging/maps/zlnhacsa/singapore-style-lab)** Open the Singapore Style Lab. `Buildings — Uniform` is on when the map opens. Each building has a thin white outline. Zoom in close to see it. ## Before you start - The layer must be a polygon layer. Lines have no outline; for a contrasting edge on lines, see [How to style line patterns and casing](/docs/styling-layers/style-line-patterns). - You need edit access to the map. - A new polygon layer starts with `Stroke` set to `None`, so it has no outline. ## Open the Style tab In the layer panel, select your polygon layer. Click the `Style` tab. ## Pick the stroke style The `Stroke` dropdown is at the end of the polygon controls, after the fill settings. It is in the same place for every colour driver: `Uniform colour` or a field. Pick one: - **`Solid`** — a continuous line. - **`Dashed`** — a dashed line. - **`Dotted`** — a dotted line. - **`None`** — no outline. The colour and width controls go away. Here `Stroke` is `Dashed` on a layer coloured by category, below its fill controls: Style section of the Countries — Income Group layer with Fill polygons by set to income_grp, the Colour scheme, fill opacity at 85%, and fill pattern Solid, then Stroke set to Dashed with a dark stroke colour swatch and the stroke width slider at 1.5 px, above Customise categories ## Set the colour and transparency Click the `Stroke colour` swatch. Pick a colour, or type a hex value. The picker also sets transparency: lower it to let the fill and the basemap show through the outline. The outline has one colour for the whole layer. It does not change by category or class break. ## Set the width Drag the `Stroke width` slider, or type a value in the box. The range is 0.5 to 10 px, in steps of 0.5 px. A new outline is 1 px wide. Dashes, dots, and gaps grow with the width. At 0.5 px the outline is thin and its dots are tiny, so use 1.5 px or more for a `Dashed` or `Dotted` outline. ## Save Click `Save` at the bottom of the panel. ## Verify the result The map redraws with the outline on every polygon. In the legend, the symbol next to the layer name shows a `Dashed` or `Dotted` outline. The swatches for each category or class show the fill only. The legend does not show the outline's width. Map viewer zoomed on Europe with the Countries — Income Group layer drawn with a dark dashed outline around each country, and the Legend open on the layer: its symbol next to the layer name has a dashed outline, and its five income group swatches, from 1. High income: OECD to 5. Low income, show the fill only ## Common problems **No outline shows.** Check that `Stroke` is not `None`, and that you clicked `Save`. Check the colour's transparency in the picker; a fully transparent colour draws nothing. **Outlines merge into one dark mass when zoomed out.** Small polygons, such as building footprints, are smaller than the outline at low zoom. Use a thinner outline, a lighter colour, or more transparency. You can also hide the layer at low zoom; see [How to set the zoom range a layer is visible at](/docs/styling-layers/set-layer-zoom-visibility). **A shared border looks thicker than the others.** Each polygon draws its own outline, so where two polygons meet, two outlines lie on top of each other. With a transparent colour, shared borders look darker. Use an opaque colour for even borders. ## What this doesn't cover - **A different outline for each category or class break.** The outline is the same for the whole layer. To set one category apart, change its fill colour or fill pattern; see [How to customise category and class break symbology](/docs/styling-layers/customise-category-and-class-break-symbology). - **Fill colour, transparency, and pattern.** See [How to set a uniform polygon style](/docs/styling-layers/set-a-uniform-polygon-style) and [How to style polygon fill patterns](/docs/styling-layers/style-polygon-fill-patterns). ## Related - [How to set a uniform polygon style](/docs/styling-layers/set-a-uniform-polygon-style) - [How to style features by category](/docs/styling-layers/style-by-category) - [How to style features by quantity](/docs/styling-layers/style-by-quantity) - [How to style polygon fill patterns](/docs/styling-layers/style-polygon-fill-patterns) - [Polygon layer style controls](/docs/styling-layers/polygon-style-reference)