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Pricing in Proportion (PiP).

The Royal Mail’s Pricing in Proportion (PiP) initiative came into effect on 21st August 2006, changing the criteria for pricing mail from weight alone to a combination of size, weight and volume. In general, the system means you pay the same or less to send small items of post, and more to send larger, bulkier items.

The Royal Mail pricing system is designed to rebalance postage prices to reflect the fact that larger, bulkier items cost more to handle than smaller, lighter ones. Here is some useful information to help you with this initiative.

There are three main size formats - Letter, Large Letter and Packet:


Letter covers items including most postcards, bills, statements and most greetings cards. The price for posting these items won't change - in fact you can still use your existing stamps on letters. The price for a small letter first class stamp currently starts at 60p. The price for a small letter first class frank starts at 44p!!

  • Length:240mm max
  • Width:165mm max
  • Thickness:5mm max
  • Weight:100g max

Large Letters

This covers items such as magazines, CDs or in some cases DVD's (depending on their thickness), and A4 envelopes. The price of a large Letter first class stamp starts at 90p. The price for a large letter first class frank starts at 66p!!

  • Length:353mm max
  • Width:250mm max
  • Thickness:25mm max
  • Weight:750g max


This covers anything longer OR, thicker OR wider than a large letter - so packets include items such as Video cassettes, books, prints and posters in cylindrical packaging.

  • Length:over 353mm OR
  • Width:over 250mm OR
  • Thickness:over 25mm OR
  • Weight:over 750g