Franking Machine Ink Explained: How to Choose, Store and Save

Choosing the right franking machine ink comes down to three things: matching the cartridge to your exact machine model, using the correct colour for your mail type (blue for Mailmark and Smart meter machines, red for older standard machines), and making sure the ink is Royal Mail approved so your franking impression scans cleanly. Get those right and you protect your print quality, keep your mail moving through Royal Mail's sorting systems, and avoid wasting money on cartridges that fail. This guide explains how to pick the correct ink, store it, and bring down your cost per print without risking your machine.

Why franking machine ink is different from ordinary printer ink

Franking ink is not the same as the ink in a home or office inkjet. When you frank an envelope you are effectively printing money, so the industry is tightly regulated. Royal Mail tests and approves the inks used for franking so that its automated mail centres can read and sort the impression reliably. Only a small number of suppliers are approved to produce Royal Mail red and blue franking ink, which is one of the reasons the cartridges cost more than standard inkjet supplies.

That premium buys you consistency. A typical franking cartridge costs somewhere between 60 and 100 pounds and yields anywhere from around 15,000 to 40,000 impressions depending on the machine, which works out at roughly 3p to 6p per franked item. Because a poor impression can be rejected by Royal Mail's readers, reliability matters more here than with everyday printing.

Blue or red? Choosing the correct ink colour

The colour you need depends on the type of franking machine you run. Modern Mailmark and Smartmeter machines must use Royal Mail approved blue ink, because the blue is formulated to let the scanners read the 2D Mailmark barcode accurately. Older standard analogue machines use approved red ink instead. If you are unsure which category your machine falls into, our companion article on Mailmark franking machines explains the difference and how to tell what you are running.

Using the wrong colour, or an unapproved ink, is a genuine risk rather than a technicality. If the impression cannot be read, items can be delayed, surcharged, or returned, which quickly cancels out any saving. When in doubt, check your machine's manual or ask your supplier before you order.

Matching the cartridge to your exact machine

Franking cartridges are model specific. A cartridge made for a Pitney Bowes machine will not fit a Quadient or FP Mailing unit, and even within one manufacturer's range the cartridges differ between models. The simplest way to avoid ordering the wrong thing is to shop by machine. At Franking Machine Supplies you can browse ink and labels by brand, whether that is Pitney Bowes, Neopost and Quadient, or FP Mailing, then narrow down to the collection for your specific model.

Have your machine's model name and number to hand before you buy. It is usually printed on the front of the unit or on a label underneath. Ordering against the model number is far safer than guessing from a photograph.

OEM versus compatible cartridges: is the saving worth it?

Genuine, manufacturer produced ink is Royal Mail approved and dependable, which is why many businesses stick with it. Good quality compatible cartridges, however, can cut your ink bill significantly, sometimes by as much as half, and there is nothing inherently wrong with a well made compatible from a reputable supplier that offers a guarantee.

The caution is around quality control. Some cheap cartridges are simply old shells that have been drilled, refilled with inferior ink and resealed, and these are prone to leaking and to producing impressions that Royal Mail's systems struggle to read. If print quality suffers, your franking can become unreadable, so it pays to buy compatibles only from a trusted source.

Worth knowing on warranties: the Office of Fair Trading ruled back in 2005 that franking machine manufacturers cannot void your machine warranty simply because you used a compatible cartridge, unless that cartridge was actually the cause of the fault. In other words, using a reputable compatible does not automatically put your cover at risk.

How to store franking ink so it lasts

Franking ink has a shelf life, and it is shorter than many people expect. As a rule of thumb, genuine cartridges keep for around two years and compatible cartridges for around three, provided they are stored well. Over time ink settles and dries inside the cartridge, which is what leads to clogging and streaky impressions.

To get the most from your stock, keep spare cartridges in a cool, dry place away from direct sunlight and heat, store them upright in their sealed packaging until you need them, and buy in quantities you will realistically use before the use by date rather than stockpiling. If your mail volumes are seasonal, it is better to reorder more often than to have cartridges expire on the shelf.

Keeping impressions crisp: simple maintenance

Most print quality problems come from a dried or partially blocked print head, which is common if the machine has stood unused for a while. If your impressions start to show broken or missing lines, run the machine's built in cleaning cycle first. If that is not enough, remove the cartridge and gently wipe the print head with a soft, lint free cloth or the alcohol wipe often supplied with the cartridge, then refit it and test again. If lines are still missing after cleaning, the cartridge itself may need replacing.

Bear in mind that keeping your machine in good working order is part of your franking licence. Royal Mail requires franking machines to be inspected at least once a year by an approved provider, so a little routine care between visits helps avoid surprises. Royal Mail sets out the official position in its franking support hub.

Do not forget your labels

Ink is only half of the consumable story. For parcels and larger items that will not fit through the machine, you frank onto self adhesive labels instead. Keeping a supply of the correct franking machine labels for your model means you are never caught short, and buying ink and labels together is a simple way to save on delivery. If you are weighing up the wider cost of franked mail against stamps, our summary of the latest Royal Mail postage rates for 2026 puts the numbers in context.

Frequently Asked Questions

What colour ink does a Mailmark franking machine use?

Mailmark and Smartmeter franking machines use Royal Mail approved blue ink. The blue formulation allows Royal Mail's scanners to read the 2D Mailmark barcode reliably. Older standard analogue machines use approved red ink instead, so always check which type your machine is before ordering.

Can I use compatible franking ink instead of the original?

Yes, provided you buy a good quality compatible from a reputable supplier that offers a guarantee. Well made compatibles can save you a substantial amount, often up to half the cost of genuine ink. Avoid cheap refilled cartridges, which can leak and produce impressions that Royal Mail's systems cannot read. A 2005 Office of Fair Trading ruling confirmed that using a compatible does not void your machine warranty unless the cartridge itself causes a fault.

How long does franking machine ink last?

Unopened, genuine cartridges typically keep for around two years and compatible cartridges for around three, if stored in a cool, dry place. In terms of usage, a single cartridge commonly yields between roughly 15,000 and 40,000 impressions depending on the machine and the size of the franking mark you print.

Why is my franking machine printing faint or streaky?

Faint or streaky impressions are almost always caused by a dried or blocked print head, which happens most often when a machine has been idle. Run the built in cleaning cycle first, then, if needed, gently wipe the print head with a soft lint free cloth or an alcohol wipe. If broken lines remain after cleaning, the cartridge has probably reached the end of its life and should be replaced.

How do I know which ink cartridge fits my machine?

Franking cartridges are model specific, so match your order to your machine's exact make and model number, which is usually printed on the front of the unit or on a label beneath it. Shopping by brand and model, rather than by appearance, is the safest way to be sure you order the correct cartridge first time.

Why is franking ink more expensive than normal printer ink?

Franking is a regulated activity because you are printing postage value, so the ink must be Royal Mail approved and tested to guarantee it can be read by automated sorting equipment. Only a handful of suppliers are approved to make it, and that combination of testing and limited supply is what pushes the price above ordinary inkjet ink. The upside is a low cost per item, typically around 3p to 6p per franked impression.