A sliding scale is a term in economics used to describe a scale where prices, taxes or wages change based on another factor such as gross sales, a cost-of-living index or income level. Under a sliding scale, you can manually calculate the prices, taxes or wages paid or received based on information about the sliding scale model and details about the sliding scale factor component.

Calculate the base and various levels for the sliding scale. For example, assume a sliding scale commission pays 10 percent based on sales of $0 to $10,000, 20 percent commission based on sales of $10,001 to $20,000, 30 percent commission based on sales of $20,001 to $30,000 and 40 percent commission based on sales over $30,001.

Calculate the gross sales for the commission period. For example, assume a salesperson had gross sales of $50,000 for the commission period.

Calculate the commission payable at the base level. Continuing the same example, the salesperson would receive commission of 10 percent for the first $10,000 in sales: $10,000 x .1 = $1,000.

Calculate the commission payable at the next level on the sliding scale. Continuing the same example, the salesperson would receive commission of 20 percent for the next $10,000 in sales: $10,000 x .2 = $2,000.

Calculate the commission payable at the next level on the sliding scale. Continuing the same example, the salesperson would receive commission of 30 percent for the next $10,000 in sales: $10,000 x .3 = $3,000.

Calculate the commission payable at the next level on the sliding scale. Continuing the same example, the salesperson would receive commission of 50 percent for the last $20,000 in sales: $20,000 x .4 = $8,000.

Add the figures from Step 3 through Step 6. Continuing the same example, $1,000 + $2,000 + $3,000 + $8,000 = $14,000. This figure represents the total commission paid under the sliding scale.