Parcel girth, volume and diagonal measure different things
Use outside dimensions for parcel measurements and inside dimensions for packing space, without confusing geometry with carrier acceptance.
Method
A parcel can have a large internal diagonal and still exceed a shipping measurement limit. Girth, length plus girth, volume and diagonal answer different questions. Label outside and inside measurements before calculating so that a packaging decision uses the right quantities.
For an ideal rectangular parcel, choose the longest outside side as length. Girth traces the rectangle around the other two sides: twice their sum. A 50-by-30-by-20 cm parcel has 100 cm girth and 150 cm length plus girth. Its outside volume is 30000 cm³, or 30 litres.
Measure finished packaging, including bulges, and confirm how the selected carrier rounds dimensions. Recheck the applicable service and destination rules at booking. The calculators provide geometric measurements; they do not certify shipping acceptance, safe stacking or adequate cushioning.
View data
- Longest side (cm)
- 50 cm
- Second side (cm)
- 30 cm
- Third side (cm)
- 20 cm
Worked example
Dimensional weight uses volume and a carrier-specified divisor in compatible units. As a purely chosen example, 30000 cm³ divided by 6000 cm³/kg gives 5 kg. That divisor is an assumption, not a claim about a particular service. Actual weight, rounding, surcharges and current service rules must be checked separately.
For an item inside a box, use measured internal dimensions. A 40-by-30-by-20 cm interior has a space diagonal of about 53.851648 cm. That is a corner-to-corner distance, not proof that a 53 cm object can pass through the opening or fit with its width and protective packaging.
girth = 2 × (width + height)
length + girth = 50 + 2 × (30 + 20) = 150 cm
outside volume = 50 × 30 × 20 = 30000 cm³
inside diagonal = √(40² + 30² + 20²) ≈ 53.851648 cm
Dimensional weight uses volume and a carrier-specified divisor in compatible units. As a purely chosen example, 30000 cm³ divided by 6000 cm³/kg gives 5 kg. That divisor is an assumption, not a claim about a particular service. Actual weight, rounding, surcharges and current service rules must be checked separately.
View data
- Longest side (cm)
- 50 cm 50 + 2 × (30 + 20) = 150 cm
- Second side (cm)
- 30 cm 2 × (30 + 20) = 100 cm
- Third side (cm)
- 20 cm 50 × 30 × 20 = 30000 cm³
Checks and limits
Measure finished packaging, including bulges, and confirm how the selected carrier rounds dimensions. Recheck the applicable service and destination rules at booking. The calculators provide geometric measurements; they do not certify shipping acceptance, safe stacking or adequate cushioning.