Long Term Disability (LTD) is expressed per $100 of benefit volume.  To calculate monthly LTD premium you take the benefit volume multiplied by the rate per $100 of coverage.  For example, if you have monthly salary of $5,000, a 66.7% LTD benefit schedule, and a rate of $1.50 per $100, the calculation is as follows: $5,000 * 0.667 / $100 * 1.50 = $50.25