About JustPayPostage
Helping people across the UK pay only what they need to for postage.
Postage prices change often and the rules about sizes and weights are confusing. It's easy to pay for a parcel when a large letter would do, or to queue at the counter when buying online would be cheaper. JustPayPostage exists to fix that.
What we do
- Our free postage calculator compares Royal Mail, Evri and InPost services for your exact size and weight.
- We keep an up-to-date list of stamp prices and international postage costs.
- Our guides explain how to pack, post and save money in plain English.
Where our prices come from
We compile prices from the carriers' own published price lists and check them regularly – they were last checked on 1 October 2026. Where a carrier doesn't publish a fixed price (for example, because prices vary by promotion), we show our best estimate and label it approx. Always confirm the final price with the carrier before you pay.
Independent and free
We are not owned by, or connected to, Royal Mail, the Post Office, Evri, InPost or any other carrier. The site is free to use and is funded by advertising and by commissions from some of the services we link to. These never affect the order of results: the calculator always sorts by price.
How we research and check our information
- Prices come from each carrier's own published price lists and price-change announcements. We recheck them whenever a carrier announces a change – Royal Mail usually changes prices in April and sometimes in October – and the date of our last check is shown on every page.
- Size and weight limits come from the carriers' own size guides. Our calculator checks every limit, including length-plus-girth rules, so it only shows services your parcel actually qualifies for.
- Estimates are labelled. If a carrier doesn't publish a fixed price for a service, we show our best estimate and mark it approx. rather than presenting it as exact.
- Guides are written in plain English and reviewed when rules change, such as customs requirements after Brexit or changes to US import rules.
How our calculator works
When you enter a size and weight, the calculator checks every service in our price list against that service's maximum dimensions and weight, works out the price band your parcel falls into, and sorts the results from cheapest to most expensive. It runs entirely in your browser – nothing you type is sent to us.
Spotted a mistake?
If you notice a price that's out of date, please let us know – we'll check and update it.