What mark up to make 12.5 percent gross profit?

If your Gross Profit is 12.5% of Selling Price, that means your Cost of Goods Sold is 87.5% of Selling Price.

1/.875 = 1.143

So you need a 14.3% markup to achieve a 12.5% Gross Profit.

Example: Cost = $100

Selling Price = $100 x 1.143 = $114.30

Gross Profit = $114.30 - $100.00 = $14.30

14.30/114.30 = 12.5%