Weight Converter:

1 inch = 2.54 cm
1 foot = 30.48 cm
1 cubic foot = 1728 cubic inches
1 cubic meter = 35.31 cubic feet
1 kilogram = 2.2046 lbs
1000 kgs = 1 metric ton
1 cubic meter = 166.66 kgs of volume weight

cubic volume is:
40x48x60=115,200 cubic inches
115,200 : 1728=66.66 cubic feet
66.66 : 35.31=1.8879 cubic meters
1.8879 x 166.66=about 315 volume kgs

The actual weight is only 551 lbs : 2.2046=250 kgs.

Your volume weight is higher than the actual weight (315 vs 250), therefore, your chargeable weight will be 315 kgs. The airlines charge based on both the actual weight and dimensional weight, where 6 cubic meters = 1000 dimensional kgs.

For International Shipments:
L x W x H (cubic inches) / 166 = Dimensional Weight.

For Domestic Shipments:
L x W x H (cubic inches) / 194 = Dimensional Weight.

CALCULATION OF VOLUME WEIGHT FOR OCEAN FREIGHT
Same example as above:
We compare your actual weight in metric tons (0.25 MT) to the volume in cubic meters (1.8879). The higher number is your chargeable volume.