Postage Calculator

1. Where are you sending?

2. What size is it?

Click a size to use it. Greyed sizes don't fit your item's dimensions.

3. Or pick a common size

Envelopes
Parcels

4. Weight & measurements

5. Prices

This calculator is provided as a guide only. Prices are based on Royal Mail rates correct as of 5th October 2026. Please check the size, weight and destination of your item carefully before posting, as prices and services may change. Stamps by Post cannot accept responsibility for underpaid postage where the item details entered are incorrect. Download our postage rate guide for details on world zones.