Parcel Girth Calculator

Last updated: June 2026

Length

Width

Height

Girth

100 cm

Length plus girth

160 cm

Formula

girth = 2 x (second-longest side + shortest side). Length plus girth = longest side + girth.

About this calculator

The Parcel Girth Calculator works out girth and length plus girth from parcel dimensions. It is useful when checking courier size limits, especially for long tubes, boxes, and bulky parcels.

Parcel Girth Calculator method

The calculator applies the visible formula to the values entered. It is designed for practical planning and checking, so keep the assumptions visible when comparing scenarios.

girth = 2 x width + 2 x height
length plus girth = length + girth

How to use the Parcel Girth Calculator

Measure the parcel length, width, and height.
Use the longest side as length if the courier defines it that way.
Enter the dimensions in centimetres.
Review girth and length plus girth.
Compare the result with your carrier size limits.
Allow for packaging bulges and rounded edges.

Worked examples

Long rectangular box

Input: Length 100 cm, width 30 cm, height 20 cm

Calculation: girth = 2 x 30 + 2 x 20 = 100; length plus girth = 200

Result: Length plus girth is 200 cm.

Poster tube estimate

Input: Length 80 cm, width 10 cm, height 10 cm

Calculation: girth = 40 cm; length plus girth = 120 cm

Result: Use 120 cm for a length plus girth check.

When this calculator is useful

The Parcel Girth Calculator works out girth and length plus girth from parcel dimensions. It is useful when checking courier size limits, especially for long tubes, boxes, and bulky parcels.

Use it as a quick planning tool before editing a recipe, placing an order, choosing packaging, or comparing options. For anything that affects safety, delivery terms, customer pricing, or a commercial commitment, check the final details against the original recipe, supplier, courier, or official source.

Inputs that matter most

Longest side: Couriers often define length as the longest dimension.
Irregular parcels: Measure at the widest points, including bulges.
Tubes: Tube girth may be approximated from diameter depending on courier guidance.
Limits: Length plus girth limits are separate from weight limits.

Common mistakes to avoid

Check 1: An item can pass weight limits but fail length plus girth limits.
Check 2: Soft packaging can bulge after measuring.
Check 3: Carrier staff or automated systems may measure differently.
Check 4: International services may have different size rules.

Planning notes

Area	What to check
Units	Keep grams, millilitres, centimetres, kilograms, and time units consistent.
Rounding	Round practical kitchen or shipping values after checking the calculated result.
Tolerance	Allow margin for packaging, recipe texture, oven variation, courier rules, or handling space.

Edge cases

An item can pass weight limits but fail length plus girth limits.
Soft packaging can bulge after measuring.
Carrier staff or automated systems may measure differently.
International services may have different size rules.

Limitations

This is a parcel size estimate. Courier size rules can change and may vary by service.

The calculator gives measurements, not a booking guarantee.
Always compare with the exact courier and service size limits.

Frequently asked questions

What is parcel girth?

It is usually twice the width plus twice the height.

What is length plus girth?

It is the parcel length added to the girth measurement.

Why do couriers use girth?

It helps limit bulky or awkward parcels that take up space.

Should I round up dimensions?

Yes, rounding up is safer for booking and avoiding surcharges.

Does girth apply to every parcel?

Not every service uses it, but many carriers use size formulas or maximum combined dimensions.

Related calculators

volumetric-weight-calculator
dimensional-weight-calculator
royal-mail-parcel-size-checker

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.