Large Letter Franking: How Much You Save in 2026

If your business posts brochures, invoices, contracts or A5 booklets, most of your postage spend goes on large letters — and that is exactly where a franking machine saves you the most. Under the Royal Mail rates that took effect on 7 April 2026, Mailmark franking cuts up to 44p off a single first class large letter, a 13.33% discount versus buying a stamp. This guide explains the 2026 large letter rates in plain terms, shows you the saving at every weight, and helps you work out what your own postbag could save.

Why large letters are where franking pays off most

On a standard letter the franking discount is small: a second class letter costs 91p as a stamp and 88p franked, a saving of 3p. Useful at volume, but modest per item.

Large letters are a different story. Royal Mail applies a much bigger franking discount to this format, because it wants to reward businesses that pre-sort and process their own mail. On a first class large letter up to 100g, the stamp price is £3.30 but the Mailmark price is just £2.86 — you keep 44p on every single item.

Since large letters carry the heaviest per-item postage of any everyday business format, a percentage discount there translates into real money. The same 13.33% applied to a bag of stamped letters would be almost invisible; applied to large letters, it adds up quickly.

The 2026 large letter rates: stamp vs Mailmark

Here are the current first class large letter prices, effective 7 April 2026. All franking prices are VAT exempt.

Second class large letters are cheaper to start with, so the cash saving is smaller, but it still grows with weight.

You can view the full breakdown, including every weight step and other services, on our Royal Mail postage rates page.

What counts as a large letter (so you don't overpay)

Getting the format right matters as much as the discount, because a misclassified item is charged at the wrong rate. Royal Mail defines a large letter as up to 353mm long, 250mm wide and 25mm thick, weighing up to 750g. That covers most C5 and C4 envelopes and anything with a few folded pages inside.

Anything thicker than 25mm, or heavier than 750g, becomes a parcel and is priced differently. A franking machine with an integrated or connected scale removes the guesswork by weighing and rating each item automatically, so you always apply the correct — and cheapest valid — price.

This is a common source of waste with stamps. Staff round up to a first class large letter stamp "to be safe", when the item would have gone second class or as a standard letter. Franking prices the item exactly.

Working out your annual saving

The maths is simple once you know your volume. Take 1,000 first class large letters up to 100g. As stamps that costs £3,300. Franked with Mailmark it costs £2,860 — a difference of £440 on that batch alone.

Scale it to a realistic postbag. A firm sending 250 first class large letters a week saves roughly £110 a week at the 44p rate, which is over £5,700 across a year before you even count the smaller savings on standard letters and heavier items.

Your figure will depend on your mix of first and second class, the weights you send, and your total volume. The key point is that the heavier and more large-letter-weighted your post is, the faster franking pays for itself. You can read more about the wider benefits on our franking machine benefits page.

Frequently Asked Questions

How much does franking save on a large letter in 2026?

The largest saving is 44p per item on a first class large letter up to 100g: £3.30 as a stamp versus £2.86 with Mailmark franking, a discount of 13.33%. Savings on heavier first class large letters range from 30p to 32p, while second class large letters save between 3p and 20p depending on weight. All franking prices are exempt from VAT and took effect on 7 April 2026.

What is the difference between a stamp and Mailmark franking?

A stamp is a fixed pre-paid price you buy over the counter, while Mailmark is Royal Mail's barcoded franking standard that gives businesses a discounted postage rate when they process mail through an approved franking machine. Mailmark prices are consistently lower than stamp prices, especially on large letters, and the discount is applied automatically each time you frank an item.

What size is a Royal Mail large letter?

A large letter can be up to 353mm long, 250mm wide and 25mm thick, and can weigh up to 750g. Anything exceeding those dimensions or weight is classed as a parcel and priced under parcel rates instead. Most C4 and C5 envelopes containing folded documents fall within the large letter format.

Do I need a Mailmark machine to get these prices?

Yes. The discounted large letter prices shown here are Mailmark rates, so you need a Mailmark-compliant franking machine to access them. All current machines we supply are Mailmark ready, which also gives you a cleaner franking impression and the option to add a return address or advert to each item.

The bottom line

For any UK business that sends large letters, franking is the single easiest way to cut postage costs in 2026. The 44p per-item saving on first class large letters — 13.33% off the stamp price — compounds fast across a busy postbag, and Mailmark also removes the risk of overpaying through misclassified items. If large letters make up a meaningful share of your post, it is worth checking the numbers against your own volume. Browse our full range of Mailmark franking machines to see which model fits your mailroom.