Add Grid to Layout

QGIS can already do all of this. What it cannot do is do it quickly: the grid lives in the layout designer's item properties panel, behind Grids, a + button, a Modify grid… button and five collapsible sections, and the interval, the frame, the label format and each side's label orientation are in four different places. This is the same settings in one form, with a Suggest button that works the interval out from what the map is actually showing.

It also edits the grids a map already has, not only new ones, so it is the faster way back in when an interval turns out wrong at print size.

And it draws an MGRS grid, which QGIS cannot do at all: there is no MGRS anywhere in the QGIS API.

The tool needs a print layout with a map item on it. Run it without one and it says so and stops.

1. Open the layout in Project > Layouts, and click the map item to select it.
2. Back in the main window, run KGA Mapping > Add Grid to Layout. The window opens on that layout and that map, in front of the layout designer rather than behind it, so the form and the sheet are on screen together.
3. Pick a Preset if one is close to what you want.
4. Press Suggest to get a round interval for the scale the map is at.
5. Set the frame and the label sides, then press Add Grid.
6. Look at the sheet, change a number, press Apply again. Repeat until it reads right at print size.

The MGRS preset

A grid reference such as 48P VT 92 77 is four things: the zone number, the latitude band letter, the 100 km square letters and the numeric location. They are read off different grids, so the preset lays down four, plus up to three more you can tick on.

1. Select the map and run the tool as above.
2. Pick MGRS grid from the bottom of the Preset list. Nothing is written yet: the button changes to Add MGRS Grid (4 grids) and its count follows what you tick.
3. Set the font, colours and frame if you want them different — everything the set does not fix for itself is taken from the form when you press Add.
4. Choose whether the 100 km letters go in the margin or inside the map. Inside keeps the margin to the numbers alone, which is how a printed sheet does it.
5. Set the Grid interval if Automatic is not what the sheet needs. Tick 1 km mesh and Labels inside too if you want them.
6. Press Add MGRS Grid. One undo step; the tool is left editing the fine grid, and the others are in the Grid list.

• It checks there is something to grid before it opens. A project with no layout — or with layouts carrying no map item — gets a message saying which of the two is missing, and nothing opens.
• MGRS is written in this plugin, because QGIS has none. There is no MGRS in the QGIS C++ or Python API. The maths is WGS84 only, no UPS, and is checked against PROJ and against the standard 4QFJ 12345 67890 example.
• The GZD graticule draws nothing on most sheets. Its lines are 6° apart across and 8° up, so on any map smaller than a zone cell there is no line to draw. On a single-zone sheet, put 48P in a layout label instead.
• Above 84° N and below 80° S there is no MGRS grid. Those latitudes use UPS, which the tool does not draw. The preset refuses and says so.
• One sheet, one zone. All the grids use the zone at the middle of the map. A map crossing a zone boundary is gridded anyway and warned about. That is a property of MGRS, not of this tool.
• The labels are an expression, so they survive without the plugin. They are written as QGIS's own Custom annotation format with self-contained expression text. The cost is that QGIS's Decimals setting stops applying, which is why that row is hidden for these formats.
• The margin never prints a single digit. The labels are floored at two, which is the convention on a 1:50,000 sheet — a margin of bare single digits reads as a ruler rather than as coordinates.
• The raised 100 km digits are Unicode superscripts. QGIS gives a grid one font per label, so there is no way to set part of it smaller. Nearly every font has these glyphs, but one that does not will draw boxes.
• The 1 km mesh carries no numbers. A second row of labels would land in the same margin row and overlap it. The mesh is there to measure against, not to name.
• Interior labels are a grid of their own. QGIS gives one grid a single label position per side, so repeating the numbers inside the frame needs a second grid rather than a second setting.
• The interval is in the grid's CRS, not the map's. Switching to EPSG:4326 with an interval of 1000 left over from a metre grid means 1000 degrees, and draws nothing. The tool re-suggests the interval whenever the CRS changes.
• Fit the page automatically cannot carry MGRS digits. QGIS recomputes that interval at every render and the expression cannot follow it, so the combination is refused.
• Labels outside the frame draw beyond the map item's rectangle. They can overrun a neighbouring item or the edge of the page; the map item does not grow to make room.
• The window follows the layout it is working on, and closing that designer closes this window with it. Nothing is lost — the grid is already on the map; re-run the tool and pick it under Grid.
• Only print layouts are offered. A report is not a layout the tool can put a grid on.