How to Calculate Shipping Costs for Different Mailer Sizes
Calculate shipping costs by mailer size and optimise for the cheapest rates.
Royal Mail rates
Quick answer
Small bubble mailers (sizes A-C) with thin items can qualify for large letter rates (from 93p), saving over £2 vs small parcel (from £3.35). The 25mm thickness limit is critical: bubble padding takes up 10-15mm, leaving only 10-15mm for contents. Always measure the packed, sealed mailer. Larger sizes and thicker items ship as small parcels. Compare Royal Mail with courier rates for heavier shipments.
Courier rates
Most couriers charge by actual or dimensional weight (whichever is greater). Bubble mailers are lighter than boxes, often resulting in cheaper courier rates. Some couriers offer specific "mailer" rates for flat packages.
Sizing: size guide or postal rules.
Optimisation tips
Save on postage0 / 3 checked
Postage-optimised bubble mailers
Sized for cheapest shipping from ProcuraPack.
Browse bubble mailersFrequently asked questions
Small sizes with thin items can if packed thickness stays under 25mm.
Over £2 per item vs small parcel rates.
Always packed. Contents and bubble padding add significant thickness.
Sometimes. Compare rates for your typical weight and dimensions.
3-4 to cover your product range and optimise postage by size.
Part of our guide
Product Guide: Bubble Mailers
Expert guides on bubble mailers and cushioned shipping envelopes for safe, efficient deliveries.
Browse all guides →
