Sending an A4 envelope through the post
There’s something reassuring about sending an A4 envelope. Whether it’s a document, a heartfelt letter or a printed form, knowing it will arrive safe and sound is always comforting. But one common question lingers—how many stamps do you need for an A4 envelope? The answer depends not just on the size, but also the thickness and weight of what’s inside.
Size and weight matters
An A4 envelope typically falls into the ‘Large Letter’ category when posting within the UK. This means it’s larger than a standard letter and requires a different type of stamp. The Royal Mail defines a Large Letter as anything up to 35.3cm x 25cm, up to 2.5cm thick, and weighing up to 750g. Most A4 documents in a flat envelope will fall under the lower weight band—up to 100g.
Stamps for an A4 envelope up to 100g
If your A4 envelope weighs up to 100g, you’ll need one Large Letter stamp. These are different from regular first or second class stamps and are priced slightly higher to reflect the larger size. A first class Large Letter stamp currently covers this size and weight band, and it offers next-day delivery in most cases. For second class, the delivery is usually two to three working days.
What if it’s heavier or bulkier?
If you’ve popped in a few sheets of paper, a booklet or anything that makes the envelope feel thicker or heavier, it’s important to weigh it before posting. If it weighs more than 100g, you may need more postage. For example, if your envelope is between 101g and 250g, the cost will go up, and you may need two or more stamps depending on what you’re using. Using standard stamps to make up the value is possible, but it’s often easier to use a single Large Letter stamp that covers the correct amount.
Where to get the right postage
You can pick up Large Letter stamps at most post offices and supermarkets with a kiosk or service desk. Or, if you have a set of scales at home, you can use Royal Mail’s website to check postage costs and print your own label. It’s always better to double-check the weight before posting, as underpaying could mean your recipient is asked to cover the difference—which can be a bit of a bother.
A4 does not always mean Large Letter
Although most A4 envelopes fit the Large Letter category, it really depends on how much is inside. A thin A4 envelope with just one or two sheets might just about qualify as a standard letter if it’s under the size limits—but it’s rare. As soon as the envelope becomes thicker than 5mm or heavier than 100g, it no longer counts as a standard letter and definitely needs Large Letter postage.
You can use multiple standard stamps if needed
If you don’t have a Large Letter stamp handy, you can make up the value using regular first or second class stamps. For example, if the postage required is £1.55 and you only have first class stamps worth 85p each, two will do just fine. It’s a flexible little system, as long as the total value meets or exceeds the required postage for that size and weight.
Always seal your envelope securely
A4 envelopes sometimes struggle to hold onto their contents if they’re overstuffed or not properly sealed. Using a small piece of tape can help give you peace of mind that everything will stay neatly tucked in during its travels. And if you’re posting something precious or confidential, consider a more robust envelope or even tracked delivery for extra security.
Avoid underpaying—Royal Mail will charge the recipient
One thing people don’t always realise is that if you don’t put enough postage on an envelope, Royal Mail won’t just return it—they’ll deliver it to the recipient with a surcharge to pay. It’s not the nicest surprise to receive, especially for something like a birthday card or personal letter. A quick weigh-in or price check beforehand saves that awkward moment.
Posting multiple A4 envelopes? Consider Click & Drop
If you’re regularly sending out A4-sized items—whether documents, orders or little care packages—Royal Mail’s Click & Drop service is wonderfully handy. It lets you weigh and pay for postage online, print your labels at home, and drop everything off at your convenience. It adds a lovely layer of flexibility to your posting routine.
Summary
To send an A4 envelope in the UK, one Large Letter stamp is usually enough—as long as the envelope is up to 100g and not too bulky. If it’s heavier or contains something a little thicker, it’s worth weighing it first to avoid underpayment. With the right postage in place, your envelope will be ready to set off on its journey, bringing something meaningful through the post in that perfectly-sized little package.