Royal Mail Postage Cost Calculator: Franked vs Stamp Prices 2026

Need to know what something will cost to post? Pick the format, enter the weight, choose 1st or 2nd Class and how many you're sending, and this calculator shows you the stamp price and the franked price side by side, for one item and for the whole batch.

Size and weight bands

Royal Mail prices depend on format first and weight second. Get the format wrong and you'll get the price wrong. These are Royal Mail's standard UK limits (checked October 2026):

Format	Max size	Max thickness	Max weight
Letter	24cm x 16.5cm	5mm	100g
Large letter	35.3cm x 25cm	2.5cm	750g
Small parcel	45cm x 35cm	16cm	2kg

If an item's even slightly thicker than 2.5cm, it's a small parcel, not a large letter.

Price table: letters and large letters

These are Royal Mail's prices from 7 April 2026. Stamp prices come from Royal Mail's UK stamp price list; franked prices from its Business Price Guide (both checked October 2026). All exempt from VAT.

Format	Weight up to	1st stamp	1st franked	2nd stamp	2nd franked
Letter	100g	£1.80	£1.77	91p	88p
Large letter	100g	£3.30	£2.86	£1.55	£1.52
Large letter	250g	£3.60	£3.28	£1.90	£1.81
Large letter	500g	£3.60	£3.30	£2.40	£2.30
Large letter	750g	£3.60	£3.30	£2.70	£2.50

Small parcels

Royal Mail's April 2026 Business Price Guide listed Mailmark franked small parcels up to 2kg at £5.45 for 1st Class and £4.25 for 2nd Class. Royal Mail then changed several parcel prices on 5 October 2026. At the time of checking (October 2026), Royal Mail's own 2nd Class page listed a 2nd Class small parcel up to 2kg at £4.60 at the counter and £4.40 online. Because parcel prices have moved mid year, check Royal Mail's current guide or your machine's downloaded tariff before relying on parcel figures.

Franking saving

The calculator works out the saving by taking the franked total from the stamp total. A few rules of thumb:

• Standard letters: 3p saved per item, 1st or 2nd Class.
• 1st Class large letters: 30p to 44p saved per item. This is where franking earns its money.
• 2nd Class large letters: 3p to 20p saved, depending on weight.

So a batch of 100 1st Class large letters under 100g costs £330 with stamps and £286 franked, a £44 saving. A batch of 100 2nd Class letters costs £91 with stamps and £88 franked, a £3 saving.

Want to know if that adds up to enough to cover a machine? Try our franking savings calculator.

Worked examples

Posting 50 contracts 1st Class. Each is an A4 document of about 80g in a C4 envelope, so it's a large letter under 100g. With stamps, 50 x £3.30 = £165. Franked, 50 x £2.86 = £143. Saving: £22.

Sending 200 monthly statements 2nd Class. Each is a standard letter under 100g. With stamps, 200 x 91p = £182. Franked, 200 x 88p = £176. Saving: £6.

Mailing 80 catalogues 2nd Class. Each weighs 300g and fits a large letter envelope under 2.5cm thick. With stamps, 80 x £2.40 = £192. Franked, 80 x £2.30 = £184. Saving: £8.

The pattern is clear: 1st Class large letters drive almost all the saving.

How to use it accurately

• Measure before you weigh. Format decides the price band.
• Weigh on a proper scale. Kitchen scales are often inaccurate at low weights.
• Round up, never down. A 101g large letter is in the 101g to 250g band.
• Check the class. 2nd Class is fine for most non urgent business post and costs much less.

Tips for cutting postage costs

• Use 2nd Class for anything that isn't urgent. A 2nd Class large letter under 100g costs £1.52 franked, against £2.86 for 1st Class.
• Watch the thickness. Anything over 2.5cm becomes a small parcel, which costs much more than any large letter band.
• Avoid crossing weight bands. A large letter at 260g pays the 251g to 500g rate. Lighter paper or a smaller enclosure can drop it a band.
• Batch your post so you can compare totals and spot expensive items.

Small changes like these often save more over a year than the franking discount itself, so they're worth doing whichever way you pay for postage.

FAQs

Why is a large letter so much more expensive than a letter?

Large letters cost more to handle. A 1st Class large letter up to 100g is £3.30 with a stamp against £1.80 for a letter.

Does the calculator include Signed For or Special Delivery?

No, it covers standard 1st and 2nd Class. For tracked and signed services, see our recorded delivery guide.

Are online prices different from stamp prices?

For standard letters, Royal Mail's online prices match stamp prices. For 1st Class large letters up to 100g, the April 2026 online price was £3.20 against £3.30 for a stamp. See our Royal Mail prices page.

Looking for a deal?

If your batches show big franking savings, a machine could pay for itself. Compare franking machine prices. See also our labels guide and stamp costs.