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For a different question I composed this answer , including this sample code . In that code I use the mouse wheel to zoom in/out of an HTML5 Canvas. I found some code that normalizes speed differences between Chrome and Firefox. However, the zoom handling in Safari is much, much faster than in either of those. Here's the code I currently have: var handleScroll = function(e){ var delta = e.wheelDelta ? e.wheelDelta/40 : e.detail ? -e.detail/3 : 0; if (delta) ... return e.preventDefault() && false; }; canvas.addEventListener('DOMMouseScroll',handleScroll,false); // For Firefox canvas.addEventListener('mousewheel',handleScroll,false); // Everyone else What code can I use to get the same 'delta' value for the same amount of mouse wheel rolling across Chrome v10/11, Firefox v4, Safari v5, Opera v11 and IE9? This question is related, but has no good answer. Edit : Further investigation shows that one scroll event 'up' is: | evt.wheelDelta | evt.detail ------------------+----------------+------------ Safari v5/Win7 | 120 | 0 Safari v5/OS X | 120 | 0 Safari v7/OS X | 12 | 0 Chrome v11/Win7 | 120 | 0 Chrome v37/Win7 | 120 | 0 Chrome v11/OS X | 3 (!) | 0 (possibly wrong) Chrome v37/OS X | 120 | 0 IE9/Win7 | 120 | undefined Opera v11/OS X | 40 | -1 Opera v24/OS X | 120 | 0 Opera v11/Win7 |

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