How do I prevent the scale labels from being cut off in chartjs?

You can also set a padding in the layout configuration (in chart.js 2 at least):

options: {
    layout: {
        padding: {
            left: 10
        }
    }
}

http://www.chartjs.org/docs/latest/configuration/layout.html

Add scale label option with whitespace before value. 2 or more whitespaces is allowed.

scaleLabel: "<%= ' ' + value%>"