Fat balls, suet cakes and suet pellets

Fat balls and suet are cheap, easy and popular with tits, sparrows and starlings. They are also the food most often sold in a way the RSPB tells you not to use. This guide covers the three common forms, how to hang them, and what changes with the weather. Where suet sits among all the other foods is in bird foods compared; the wider winter picture is in feeding garden birds in winter.

The sources, opened on 14 November 2026, are the RSPB’s bird café page, the RSPB’s bird feeding page, the RSPB’s latest feeding guidance, dated 30 October 2026, and the BTO feeding page. No product page was opened, so no brand, size or price is given.

Three forms of the same food

• Fat balls are suet mixed with seed or other ingredients and pressed into a ball.
• Suet cakes or blocks are the same idea in a flat slab, made to fit a square cage feeder.
• Suet pellets are small loose pieces. The BTO notes that some seed mixes now contain added suet pellets.

The RSPB’s feeding page groups them together as “suet (pellets, cakes and balls)” and describes suet as a high-energy food rich in fat, enjoyed by a range of species. Its café page pairs a hanging mesh feeder of fat balls with tits, sparrows and starlings.

Take them out of the net bag

Fat balls are still regularly sold in thin nylon mesh bags, ready to hang. The RSPB is direct about this: “Never put out any food in mesh bags.” It says the bags “may trap birds’ feet and even cause broken feet and legs”, and that birds with a barbed tongue, like woodpeckers, can become trapped by their beaks.

So the first job with a new pack of fat balls is to cut the net off and throw it away, not to hang it up. Put the balls in a proper hanging fat-ball feeder instead: a rigid cage with gaps birds can peck through but cannot catch a foot in. Suet cakes go in a square cage made for them.

This is different from the rigid steel mesh peanut feeders the RSPB recommends for nuts. Rigid mesh holds its shape. A soft net bag does not. Peanuts have their own guide.

Hang it, do not leave it on a flat surface

The RSPB’s October 2026 guidance is against flat surfaces such as bird tables and trays, because disease spreads more easily there. Suet pellets are the form most likely to end up scattered on a table. If you use pellets, a hanging feeder that holds them is the option that fits that advice. Where to hang it is in where to put a bird feeder.

Weather: cold is easy, heat is not

Fat is a winter food in most people’s minds, and the RSPB says peanuts and fat give birds protein and fat in the colder months. Fat balls are easy to use in cold weather: they stay firm and keep for a while in a feeder.

Heat is where the RSPB gives a warning. Its café page says: “In hot weather suet may go soft or spoil, particularly homemade fat balls/cakes, and we advise avoiding them.” It also says that in the warmer months it is important to buy suet products that state they are resistant to melting in hot weather.

In practice that means:

• In a hot spell, do not put out homemade fat balls or cakes.
• If you feed suet in summer, choose a product that says it resists melting, and check the packet rather than assuming.
• Take down anything that has gone soft, greasy or smelly, and clean the feeder before refilling.

Can it stay out in summer?

Fat and suet are treated differently from seeds and peanuts in the current advice. The RSPB’s October 2026 guidance says that from 1 May to 31 October you should pause seeds and peanuts, but “you can continue to offer small amounts of mealworms, fat balls or suet”. Its reasoning: “As finches rarely eat fat balls, suet and mealworms, we consider these foods are low risk” for the finch disease trichomonosis. The BTO’s page likewise talks about continuing fat and suet provision year-round.

“Small amounts” is the key phrase, and the hot-weather warning still applies. The full reasoning on the seasonal split is in what to feed garden birds.

The seven-day rule

The RSPB gives a time limit. Food in feeders should be eaten in one or two days, and suet within seven days; the October guidance says suet products can be left out for up to seven days. If a fat-ball feeder still has old food in it after a week, the feeder is too big or too full for your garden. Put out less.

Cleaning a fat-ball feeder

Fat leaves a greasy film that seed does not. Warm water and a brush shift it better than a cold rinse. The routine in cleaning bird feeders applies: the RSPB says feeder hygiene needs to be done weekly, and that you should clear old food and droppings from beneath feeders. Crumbled fat ball under a feeder is food for rats as well as birds; see rats and bird feeders.

Store unopened packs somewhere cool and in a sealed bin, as the RSPB asks for all bird food.

Should I take fat balls out of the net?

Yes. The RSPB says never put out any food in mesh bags, because they can trap birds’ feet, break legs and catch woodpeckers by the beak. Use a rigid fat-ball feeder.

Can I feed fat balls in summer?

The RSPB’s October 2026 guidance says small amounts of fat balls or suet can continue from May to October. In hot weather it advises avoiding homemade fat balls and buying products that say they resist melting.

How long can suet stay in the feeder?

The RSPB says suet should be eaten within seven days. If it is not, put out less next time.