How this calculation works
This models a closed rectangular solid. Surface area includes all six faces and assumes no material thickness.
Volume = length × width × height; surface area = 2(lw + lh + wh)A worked example
A 5 × 4 × 3 cuboid has volume 60 and surface area 94.
Good to know
Uses the stated formula and assumptions. Displayed decimal values are rounded; use consistent units for all inputs.
Cubic measurements amplify unit mistakes
A box measuring 1 m on each side contains 1 m³. The same sides are 100 cm, and the volume is 100 × 100 × 100 = 1,000,000 cm³. Converting a volume requires cubing the length conversion factor.
Multiplying three dimensions that use different units without conversion can therefore create a large error. Choose one unit for all sides before calculating.
Enclosed space and construction material are different
The volume is the space of the full rectangular solid defined by your dimensions. The material in a box with walls requires outer and inner measurements, while an open top changes the relevant surface area.
The displayed surface area includes all six faces. For a room or packaging project, decide which faces actually need treatment and subtract openings or excluded surfaces explicitly.
A few questions, answered
Can I use this for a cube?
Yes. Enter equal length, width and height.
Is surface area expressed in cubic units?
No. Surface area uses square units; volume uses cubic units.