diff --git a/packages/material-ui/src/Grid/Grid.js b/packages/material-ui/src/Grid/Grid.js
index e3b05a2c5d3859..2915529d2db903 100644
--- a/packages/material-ui/src/Grid/Grid.js
+++ b/packages/material-ui/src/Grid/Grid.js
@@ -44,8 +44,8 @@ function generateGrid(globalStyles, theme, breakpoint) {
       return;
     }
 
-    // Only keep 6 significant numbers.
-    const width = `${Math.round((size / 12) * 10e6) / 10e4}%`;
+    // Keep 7 significant numbers.
+    const width = `${Math.round((size / 12) * 10e7) / 10e5}%`;
 
     // Close to the bootstrap implementation:
     // https://github.com/twbs/bootstrap/blob/8fccaa2439e97ec72a4b7dc42ccc1f649790adb0/scss/mixins/_grid.scss#L41