Assume, for example, that cartons are budgeted at $.04 per litre. If we forecast volume of 10,000 litres, the budget allowance for cartons is $400. If we actually sell only 8,000 litres but use $350 worth of cartons, it is misleading to say that there is a favorable variance of $50 ($350-$400). The variance is clearly unfavorable by $30 ($350-$320). This only shows up if we adjust the budget to the actual volume level: