diff --git a/manual.html b/manual.html
index b69d10c..bbe6686 100644
--- a/manual.html
+++ b/manual.html
@@ -45,6 +45,8 @@
 <h3>Diagram</h3>
 <p>Hover with the mouse cursor over the diagram to see the heat and humidity coordinates at this position. You can click on a dot to select it, click on it again and hold down the mouse button to drag it.</p>
 
+<p>When you hover the diagram, a small grabbing widget will apper in the bottom left corner. You can use this to resize the whole diagram. Hold down Shift while resizing to preserve the aspect ratio.</p>
+
 <h3>Biome configuration</h3>
 <p>Here you can see a list of all currently active biomes. Each biome has a name of your choice. The program always starts with a default biome at (50, 50). Select a biome in the list so you can edit it.</p>
 
diff --git a/mibpov.js b/mibpov.js
index 730c4ee..af9f4cc 100644
--- a/mibpov.js
+++ b/mibpov.js
@@ -7,6 +7,12 @@ const MAX_Y_DEFAULT = 31000
 // Draw a grid line every GRID_STEP units
 const GRID_STEP = 10
 
+// Size of the resizing corner
+const RESIZE_CORNER = 18;
+
+// Minimum canvas side length (px)
+const MIN_CANVAS_SIZE = 100;
+
 // Grid widths. We use lower grid widths
 // as the grid becomes more crammed.
 // There are 4 levels from 0 to 3.
@@ -221,6 +227,10 @@ function addBiome(biomeDef) {
 	lastBiomeID++;
 }
 
+// Current cursor position on the canvas
+let canvas_cursor_x = null;
+let canvas_cursor_y = null;
+
 // Add a default biome at the midpoint
 addBiome({name: "default", heat:midpoint_heat, humidity:midpoint_humidity, min_y: MIN_Y_DEFAULT, max_y: MAX_Y_DEFAULT})
 
@@ -919,6 +929,27 @@ function draw(recalculate) {
 			putPointName(context, point);
 		}
 	}
+
+	if (canvas_cursor_x !== null) {
+		const RESIZE_CORNER = 14;
+		context.beginPath();
+		context.moveTo(voronoiCanvas.width, voronoiCanvas.height - RESIZE_CORNER);
+		context.lineTo(voronoiCanvas.width - RESIZE_CORNER, voronoiCanvas.height);
+		context.lineTo(voronoiCanvas.width, voronoiCanvas.height);
+		context.fillStyle = "#80808080";
+		context.closePath();
+		context.fill();
+
+		context.beginPath();
+		context.lineWidth = 1;
+		for (let c = RESIZE_CORNER; c>0; c-=4) {
+			context.moveTo(voronoiCanvas.width, voronoiCanvas.height - c);
+			context.lineTo(voronoiCanvas.width - c, voronoiCanvas.height);
+		}
+		context.strokeStyle = "#00000080";
+		context.closePath();
+		context.stroke();
+	}
 	return true;
 }
 
@@ -1096,6 +1127,15 @@ function getNearestPointFromCanvasPos(x, y, maxDist) {
 
 // Whether the mouse is currently pressed
 let mouseIsDown = false;
+// Whether the canvas is being resized
+let resizing = false;
+// Start coordinates of canvas resize or null if not resizing
+let resizing_start_pos_x = null;
+let resizing_start_pos_y = null;
+// Start size of canvas when resizing or null if not resizing
+let resizing_start_size_x = null;
+let resizing_start_size_y = null;
+
 // Coordinates of where the drag-n-drop started
 // or is about to start
 let dragDropStartPos = null;
@@ -1149,6 +1189,10 @@ function updateAltitudeText() {
 /* Update the text that shows the biome coordinates
 of the cursor when it's on the diagram */
 function updateCoordinateDisplay(pixelX, pixelY) {
+	if (pixelX === null || pixelY === null) {
+		coordinateDisplay.innerHtml = "&nbsp;";
+		return;
+	}
 	// show coordinates
 	let [heat, humidity] = canvasPixelCoordsToBiomeCoords(pixelX, pixelY);
 	if (!drawError) {
@@ -1162,21 +1206,27 @@ function updateCoordinateDisplay(pixelX, pixelY) {
 /* Updates and changes the cursor type on the diagram
 canvas depending on whether we can select, drag or do nothing
 at the pointed position */
-function updateDragDropCursorStatus() {
+function updateCanvasCursorStatus(x, y) {
+	// Show resize cursor at the bottom right corner
+	if (resizing || (x > voronoiCanvas.width - RESIZE_CORNER && y > voronoiCanvas.height - RESIZE_CORNER)) {
+		voronoiCanvas.style.cursor = "nwse-resize";
+		return
+	}
+
 	if (drawError || !showPoints) {
 		// a special message is shown; use auto cursor
 		voronoiCanvas.style.cursor = "auto";
 		return
 	}
 
-	let nearest = getNearestPointFromCanvasPos(event.offsetX, event.offsetY, POINT_SELECT_DISTANCE);
+	let nearest = getNearestPointFromCanvasPos(x, y, POINT_SELECT_DISTANCE);
 	if (nearest !== null) {
 		let [id, elem] = getSelectedBiomeIDAndElement();
 		if (id !== null && nearest.id === id) {
 			// This cursor indicates we can grab the point
 			voronoiCanvas.style.cursor = "grab";
 		} else {
-			// This cursor indicates we can grab the point
+			// This cursor indicates we can select the point
 			voronoiCanvas.style.cursor = "crosshair";
 		}
 	} else {
@@ -1237,9 +1287,58 @@ function initBiomeColorSelectors() {
 
 /***** EVENTS *****/
 
-/* Canvas events */
+/* Body events */
+document.body.onmousemove = function(event) {
+	if (resizing) {
+		// Get x,y position of canvas
+		let bodyRect = document.body.getBoundingClientRect();
+		let canvasRect = voronoiCanvas.getBoundingClientRect();
+		let cx = canvasRect.left - bodyRect.left;
+		let cy = canvasRect.top - bodyRect.top;
 
+		// Calculate new size
+		let rx = event.pageX - resizing_start_pos_x - cx;
+		let ry = event.pageY - resizing_start_pos_y - cy;
+
+		// Limit the width
+		let maxX = (bodyRect.width - cx) - 20;
+
+		// Resize
+		voronoiCanvas.width = Math.min(maxX, Math.max(MIN_CANVAS_SIZE, resizing_start_size_x + rx));
+
+		// Holding down Shift preserves aspect ratio
+		if (event.shiftKey) {
+			voronoiCanvas.height = voronoiCanvas.width;
+		} else {
+			voronoiCanvas.height = Math.max(MIN_CANVAS_SIZE, resizing_start_size_y + ry);
+		}
+		draw(false);
+		return;
+	}
+}
+document.body.onmouseup = function(event) {
+	if (resizing) {
+		resizing = false;
+		updateCanvasCursorStatus(event.offsetX, event.offsetY);
+	}
+}
+document.body.onmouseleave = function(event) {
+	if (resizing) {
+		resizing = false;
+		updateCanvasCursorStatus(event.offsetX, event.offsetY);
+	}
+}
+
+/* Canvas events */
 voronoiCanvas.onmousemove = function(event) {
+	if (resizing) {
+		updateCoordinateDisplay(event.offsetX, event.offsetY);
+		updateCanvasCursorStatus(event.offsetX, event.offsetY);
+		canvas_cursor_x = event.offsetX;
+		canvas_cursor_y = event.offsetY;
+		draw(false);
+		return
+	}
 	// update drag-n-drop state
 	if (dragDropState !== 2 && dragDropPointID !== null && mouseIsDown && dragDropStartPos !== null) {
 		let dist = getDistance(dragDropStartPos.x, dragDropStartPos.y, event.offsetX, event.offsetY)
@@ -1254,17 +1353,34 @@ voronoiCanvas.onmousemove = function(event) {
 		updatePointWhenDragged(dragDropPointID);
 	}
 	updateCoordinateDisplay(event.offsetX, event.offsetY);
-	updateDragDropCursorStatus();
+	updateCanvasCursorStatus(event.offsetX, event.offsetY);
+	canvas_cursor_x = event.offsetX;
+	canvas_cursor_y = event.offsetY;
+	draw(false);
 }
 voronoiCanvas.onmouseenter = function(event) {
 	updateCoordinateDisplay(event.offsetX, event.offsetY);
-	updateDragDropCursorStatus();
+	updateCanvasCursorStatus(event.offsetX, event.offsetY);
+	canvas_cursor_x = event.offsetX;
+	canvas_cursor_y = event.offsetY;
+	draw(false);
 }
 
 voronoiCanvas.onmousedown = function(event) {
 	// select point by clicking.
 	// initiate drag-n-drop if already selected.
 	mouseIsDown = true;
+
+	// Resizing the canvas
+	if (event.offsetX > voronoiCanvas.width - RESIZE_CORNER && event.offsetY > voronoiCanvas.height - RESIZE_CORNER) {
+		resizing_start_pos_x = event.offsetX;
+		resizing_start_pos_y = event.offsetY;
+		resizing_start_size_x = +this.width;
+		resizing_start_size_y = +this.height;
+		resizing = true;
+		return;
+	}
+
 	if (drawError || !showPoints) {
 		// Points need to be shown for drag-n-drop to work
 		return;
@@ -1281,7 +1397,7 @@ voronoiCanvas.onmousedown = function(event) {
 		if (alreadySelected) {
 			dragDropState = 1;
 		}
-		updateDragDropCursorStatus();
+		updateCanvasCursorStatus(event.offsetX, event.offsetY);
 	}
 }
 voronoiCanvas.onmouseup = function(event) {
@@ -1300,7 +1416,10 @@ voronoiCanvas.onmouseleave = function() {
 	dragDropStartPos = null;
 	dragDropPointID = null;
 	dragDropState = 0;
+	canvas_cursor_x = null;
+	canvas_cursor_y = null;
 	coordinateDisplay.innerHTML = "&nbsp;";
+	draw(false);
 }
 
 /* Biome list events */