diff --git a/src/traces/contour/colorbar.js b/src/traces/contour/colorbar.js
index 2c15610dbb5..68be46e0234 100644
--- a/src/traces/contour/colorbar.js
+++ b/src/traces/contour/colorbar.js
@@ -13,6 +13,7 @@ var Plots = require('../../plots/plots');
 var drawColorbar = require('../../components/colorbar/draw');
 
 var makeColorMap = require('./make_color_map');
+var endPlus = require('./end_plus');
 
 
 module.exports = function colorbar(gd, cd) {
@@ -52,7 +53,7 @@ module.exports = function colorbar(gd, cd) {
         })
         .levels({
             start: contours.start,
-            end: contours.end,
+            end: endPlus(contours),
             size: cs
         })
         .options(trace.colorbar)();
diff --git a/src/traces/contour/end_plus.js b/src/traces/contour/end_plus.js
new file mode 100644
index 00000000000..8b8e9dc3f65
--- /dev/null
+++ b/src/traces/contour/end_plus.js
@@ -0,0 +1,18 @@
+/**
+* Copyright 2012-2017, Plotly, Inc.
+* All rights reserved.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+
+'use strict';
+
+/*
+ * tiny helper to move the end of the contours a little to prevent
+ * losing the last contour to rounding errors
+ */
+module.exports = function endPlus(contours) {
+    return contours.end + contours.size / 1e6;
+};
diff --git a/src/traces/contour/find_all_paths.js b/src/traces/contour/find_all_paths.js
index 5826932509e..273368094e2 100644
--- a/src/traces/contour/find_all_paths.js
+++ b/src/traces/contour/find_all_paths.js
@@ -84,13 +84,13 @@ function makePath(pi, loc, edgeflag) {
         if(equalPts(pts[pts.length - 1], pts[pts.length - 2])) pts.pop();
         locStr = loc.join(',');
 
+        var atEdge = (marchStep[0] && (loc[0] < 0 || loc[0] > n - 2)) ||
+                (marchStep[1] && (loc[1] < 0 || loc[1] > m - 2)),
+            closedLoop = (locStr === startLocStr) && (marchStep.join(',') === startStepStr);
+
         // have we completed a loop, or reached an edge?
-        if((locStr === startLocStr && marchStep.join(',') === startStepStr) ||
-            (edgeflag && (
-                (marchStep[0] && (loc[0] < 0 || loc[0] > n - 2)) ||
-                (marchStep[1] && (loc[1] < 0 || loc[1] > m - 2))))) {
-            break;
-        }
+        if((closedLoop) || (edgeflag && atEdge)) break;
+
         mi = pi.crossings[locStr];
     }
 
diff --git a/src/traces/contour/make_color_map.js b/src/traces/contour/make_color_map.js
index 9db97262636..fc54a155705 100644
--- a/src/traces/contour/make_color_map.js
+++ b/src/traces/contour/make_color_map.js
@@ -11,13 +11,14 @@
 
 var d3 = require('d3');
 var Colorscale = require('../../components/colorscale');
+var endPlus = require('./end_plus');
 
 module.exports = function makeColorMap(trace) {
     var contours = trace.contours,
         start = contours.start,
-        end = contours.end,
+        end = endPlus(contours),
         cs = contours.size || 1,
-        nc = Math.floor((end + cs / 10 - start) / cs) + 1,
+        nc = Math.floor((end - start) / cs) + 1,
         extra = contours.coloring === 'lines' ? 0 : 1;
 
     var scl = trace.colorscale,
diff --git a/src/traces/contour/plot.js b/src/traces/contour/plot.js
index 2c0830cefd1..e33beda01f1 100644
--- a/src/traces/contour/plot.js
+++ b/src/traces/contour/plot.js
@@ -17,6 +17,7 @@ var Drawing = require('../../components/drawing');
 var heatmapPlot = require('../heatmap/plot');
 var makeCrossings = require('./make_crossings');
 var findAllPaths = require('./find_all_paths');
+var endPlus = require('./end_plus');
 
 
 module.exports = function plot(gd, plotinfo, cdcontours) {
@@ -81,9 +82,10 @@ function plotOne(gd, plotinfo, cd) {
 
 function emptyPathinfo(contours, plotinfo, cd0) {
     var cs = contours.size,
-        pathinfo = [];
+        pathinfo = [],
+        end = endPlus(contours);
 
-    for(var ci = contours.start; ci < contours.end + cs / 10; ci += cs) {
+    for(var ci = contours.start; ci < end; ci += cs) {
         pathinfo.push({
             level: ci,
             // all the cells with nontrivial marching index
@@ -163,7 +165,8 @@ function makeFills(plotgroup, pathinfo, perimeter, contours) {
 }
 
 function joinAllPaths(pi, perimeter) {
-    var fullpath = (pi.edgepaths.length || pi.z[0][0] < pi.level) ?
+    var edgeVal2 = Math.min(pi.z[0][0], pi.z[0][1]),
+        fullpath = (pi.edgepaths.length || edgeVal2 <= pi.level) ?
             '' : ('M' + perimeter.join('L') + 'Z'),
         i = 0,
         startsleft = pi.edgepaths.map(function(v, i) { return i; }),
diff --git a/src/traces/contour/style.js b/src/traces/contour/style.js
index db4042f1961..3ce4e56c64c 100644
--- a/src/traces/contour/style.js
+++ b/src/traces/contour/style.js
@@ -34,21 +34,26 @@ module.exports = function style(gd) {
 
         var colorMap = makeColorMap(trace);
 
-        c.selectAll('g.contourlevel').each(function(d, i) {
+        c.selectAll('g.contourlevel').each(function(d) {
             d3.select(this).selectAll('path')
                 .call(Drawing.lineGroupStyle,
                     line.width,
-                    contours.coloring === 'lines' ? colorMap(start + i * cs) : line.color,
+                    contours.coloring === 'lines' ? colorMap(d.level) : line.color,
                     line.dash);
         });
 
-        c.selectAll('g.contourbg path')
-            .style('fill', colorMap(start - cs / 2));
+        var firstFill;
 
         c.selectAll('g.contourfill path')
-            .style('fill', function(d, i) {
-                return colorMap(start + (i + 0.5) * cs);
+            .style('fill', function(d) {
+                if(firstFill === undefined) firstFill = d.level;
+                return colorMap(d.level + 0.5 * cs);
             });
+
+        if(firstFill === undefined) firstFill = start;
+
+        c.selectAll('g.contourbg path')
+            .style('fill', colorMap(firstFill - 0.5 * cs));
     });
 
     heatmapStyle(gd);
diff --git a/test/image/baselines/contour_edge_cases.png b/test/image/baselines/contour_edge_cases.png
new file mode 100644
index 00000000000..eb13470cd1c
Binary files /dev/null and b/test/image/baselines/contour_edge_cases.png differ
diff --git a/test/image/mocks/contour_edge_cases.json b/test/image/mocks/contour_edge_cases.json
new file mode 100644
index 00000000000..9b56c3ba3f8
--- /dev/null
+++ b/test/image/mocks/contour_edge_cases.json
@@ -0,0 +1,132 @@
+{
+  "data": [
+    {
+      "x": [0, 5],
+      "y": [0, 4],
+      "z": [[4, 3], [2, 1]],
+      "type": "contour",
+      "contours": {
+        "start": 1.1,
+        "end": 4.09,
+        "size": 1
+      },
+      "colorbar": {"x": 0.4, "y": 0.9, "len": 0.2}
+    },
+    {
+      "x": [0, 5],
+      "y": [0, 4],
+      "z": [[4, 3], [2, 1]],
+      "type": "contour",
+      "contours": {
+        "start": 1,
+        "end": 4,
+        "size": 0.9999999
+      },
+      "colorbar": {"x": 1, "y": 0.9, "len": 0.2},
+      "xaxis": "x2"
+    },
+    {
+      "z": [[0, 0, 0, 0, 0, 0],
+            [0, 0, 9, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0],
+            [0, 0, 0, -9, 0, 0],
+            [0, 0, 0, 0, 0, 0]],
+      "type": "contour",
+      "contours": {
+        "start": -0.000001,
+        "end": 0.000001,
+        "size": 0.000001
+      },
+      "colorbar": {"x": 0.4, "y": 0.65, "len": 0.2},
+      "yaxis": "y2"
+    },
+    {
+      "z": [[0, 0, 0, 0, 0, 0],
+            [0, 0, 9, -9, 0, 0],
+            [0, 0, 9, -9, 0, 0],
+            [0, 0, 9, -9, 0, 0],
+            [0, 0, 0, 0, 0, 0]],
+      "type": "contour",
+      "contours": {
+        "start": -0.000001,
+        "end": 0.000001,
+        "size": 0.000001
+      },
+      "colorbar": {"x": 1, "y": 0.65, "len": 0.2},
+      "xaxis": "x2",
+      "yaxis": "y2"
+    },
+    {
+      "z": [[0, 0, 0, 0, 0, 0],
+            [0, 9, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, -9, 0],
+            [0, 0, 0, 0, 0, 0]],
+      "type": "contour",
+      "contours": {
+        "start": -0.000001,
+        "end": 0.000001,
+        "size": 0.000001
+      },
+      "colorbar": {"x": 0.4, "y": 0.4, "len": 0.2},
+      "yaxis": "y3"
+    },
+    {
+      "z": [[0, 0, 0, 0, 0, 0],
+            [0, 0, -9, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 9, 0, 0],
+            [0, 0, 0, 0, 0, 0]],
+      "type": "contour",
+      "contours": {
+        "start": -0.0000005,
+        "end": 0.000001,
+        "size": 0.000001
+      },
+      "colorbar": {"x": 1, "y": 0.4, "len": 0.2},
+      "xaxis": "x2",
+      "yaxis": "y3"
+    },
+    {
+      "z": [[0, 0, 0, 0, 0, 0],
+            [0, 9, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, -9, 0],
+            [0, 0, 0, 0, 0, 0]],
+      "type": "contour",
+      "contours": {
+        "start": -0.0000005,
+        "end": 0.000001,
+        "size": 0.000001
+      },
+      "colorbar": {"x": 0.4, "y": 0.15, "len": 0.2},
+      "yaxis": "y4"
+    },
+    {
+      "z": [[0, 0, 0, 0, 0, 0],
+            [0, 0, 9, 0, 0, 0],
+            [0, -9, -9, -9, -9, 0],
+            [0, 0, 0, 9, 0, 0],
+            [0, 0, 0, 0, 0, 0]],
+      "type": "contour",
+      "contours": {
+        "start": -0.0000005,
+        "end": 0.000001,
+        "size": 0.000001
+      },
+      "colorbar": {"x": 1, "y": 0.15, "len": 0.2},
+      "xaxis": "x2",
+      "yaxis": "y4"
+    }
+  ],
+  "layout": {
+    "xaxis": {"domain": [0, 0.4]},
+    "xaxis2": {"domain": [0.6, 1]},
+    "yaxis": {"domain": [0.8, 1]},
+    "yaxis2": {"domain": [0.55, 0.75]},
+    "yaxis3": {"domain": [0.3, 0.5]},
+    "yaxis4": {"domain": [0.05, 0.25]},
+    "width": 600,
+    "height": 800
+  }
+}