Should I use an 18x18 or 20x20 insert for an 18 inch cover?

An 18x18 insert gives a neat, tailored shape and is easy on zippers. A 20x20 insert gives a fuller, plumper look but can strain snug covers. Choose by how loose or stretchy your cover is.

18x18 Pillow Inserts Review (2026): Worth It? Pros & Cons

Quick answer

18×18 pillow inserts like the Oubonun set of 2 are a simple way to make tired throw pillow covers look full and plump again. Each insert has a breathable 100% cotton cover and soft polyester filling, and the 18 inch square size fits the most common pillow covers sold for sofas, beds and chairs. Need covers to go with them? See our brown pillow covers 18×18 review for a warm velvet option.

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Our top pick:

Oubonun 18×18 Pillow Inserts with Cotton Cover (Set of 2)

Best for: Refreshing flat throw pillow covers on sofas, beds and accent chairs

Check current price on Amazon →

18x18 pillow inserts styling idea: a cream knit pillow on a tan leather sofa beside a green plant

Flat, lumpy throw pillows can make even a nice sofa look tired. Most of the time the cover is fine and the problem is what is inside it. A fresh pair of inserts is one of the cheapest decor upgrades you can make, and the Oubonun 18×18 set is one of Amazon’s popular home decor picks for exactly this job. Here is what you get, who it suits, and how to size, fluff and style pillow inserts so your couch looks finished.

Disclosure: As an Amazon Associate, team5e earns from qualifying purchases. If you buy through our links we may earn a small commission at no extra cost to you. Prices and availability change often, so check Amazon for the current price. Learn more.

Oubonun 18×18 pillow inserts at a glance

This is a pack of two white, square pillow inserts that measure 18 by 18 inches. Each one has a 100% cotton outer cover and a polyester fill that the brand calls 3D high-quality filling. They are meant to go inside your favorite throw pillow covers or shams, and they also work on their own as plain white pillows. If you have a few 18 inch covers that look saggy, these 18×18 pillow inserts are an easy, budget-friendly way to bring them back to life.

Pick	Best for	Why it stands out
Oubonun 18×18 Pillow Inserts with Cotton Cover (Set of 2) Great Budget Upgrade	Refreshing flat throw pillow covers on sofas, beds and accent chairs	Set of 2, 18 x 18 in, 100% cotton cover, polyester fill	See photos

Our verdict on the 18×18 pillow inserts

For most people who just want fuller, fluffier throw pillows, these 18×18 pillow inserts are a solid everyday pick. The cotton cover feels nicer than the slick polyester shells on many cheap inserts, and the set of two is handy for a sofa pair. Just remember they are polyester-filled, not down, so they will not have the soft, slouchy ‘karate chop’ look of a feather insert.

1. Oubonun 18×18 Pillow Inserts with Cotton Cover (Set of 2): Great Budget Upgrade

Great Budget Upgrade

The main reason to buy these 18×18 pillow inserts is the combination of a cotton cover and a full, fluffy polyester fill at a set-of-two price. Oubonun describes the cover as breathable and skin-friendly, and the fill as soft yet firm enough to lean against. In a real living room that means a pillow that holds its shape when you sit back on the sofa, instead of folding flat after a few days.

They are also versatile. The brand lists them as sham and cushion stuffers for couches, beds, chairs, office chairs and even the car. Because 18 inch square is the most common throw pillow size in the US, you can swap seasonal covers on the same pair of inserts all year: linen in summer, velvet or knit in winter, plaid for the holidays. For fall, our burnt orange pillows for couch styling guide shows how a chenille pair dresses up these inserts. For a breathable summer pair, see our guide to linen throw pillow covers 18×18, including what size insert to use.

What we like

Two 18 x 18 inch inserts in one pack, ready for a sofa pair
100% cotton cover feels breathable and soft
Fluffy polyester fill holds a full, rounded shape
Works with most standard 18 inch throw pillow covers

Keep in mind

Polyester fill does not give the slouchy look of a down insert
Inserts usually arrive vacuum packed and need time to fluff up
A same-size insert can look less plump than one sized up an inch or two

Best for: Refreshing flat throw pillow covers on sofas, beds and accent chairs

See photos & price on Amazon →

18x18 pillow inserts in use: plump patterned throw pillows and a fringed throw on a gray sofa

Key features of the 18×18 pillow inserts

100% cotton cover

Many budget inserts use a slippery microfiber shell. These have a 100% cotton cover instead, which the brand calls breathable and skin-friendly. In practice, cotton grips the inside of a pillow cover a little better, so the insert is less likely to slide around and leave empty corners. It also feels nicer if you use the inserts on their own as plain white pillows on a bed.

Soft, fluffy polyester filling

The fill is polyester, which Oubonun describes as 3D high-quality filling. Polyester fiber is light, springy and holds its loft well for the price. It is also a good choice for people who prefer to avoid feathers. The trade-off is that polyester feels a little bouncier than down, so these 18×18 pillow inserts give a full, rounded look rather than a soft, sinking one.

Soft yet supportive

The brand says the inserts are soft and fluffy but firm enough to lean on while you read, watch TV or hold one in your lap. That balance matters on a sofa: a pillow that is too soft collapses behind your back, while one that is too firm feels like a brick. Many people find a medium, springy pillow like this one comfortable for everyday lounging.

Set of two in the most common size

You get two inserts, each 18 by 18 inches. That is the standard size for throw pillows sold at most US stores, so the pair is easy to match with covers you already own. A matching pair on each end of a sofa is a classic styling formula, and this set covers one side, or both ends of a loveseat. For the rectangle that sits in front of them, see our guide to the 12×20 pillow insert and how to size it.

Who should buy it (and who should skip it)

Buy it if you:

Have 18 inch throw pillow covers that look flat, saggy or lumpy
Like to change pillow covers with the seasons and want one good pair of inserts underneath
Prefer a feather-free pillow with a cotton cover
Want a cheap, quick refresh for a sofa, bed or reading chair

Skip it if you:

Want the soft, slouchy designer look of a down or feather insert
Have 20 inch or 22 inch covers (buy that size, or one inch larger, instead)
Need a firm lumbar or back-support pillow for long sitting at a desk
Want colored pillows with no cover at all; these inserts are plain white

How to style 18×18 pillow inserts in your home

The insert is the hidden part of every great throw pillow. A few ideas to get the most out of a pair:

Sofa pair: put matching covers on two 18×18 pillow inserts and place one at each end of the couch. Add one 20 or 22 inch pillow in back and one lumbar pillow in front for a layered look.
Mix patterns: combine one solid, one stripe or check, and one larger print in the same color family. Keep at least one color repeated across all covers.
Bed styling: lean two 18 inch pillows in front of your sleeping pillows or euro shams. White inserts with cotton covers also look clean on their own in a neutral bedroom.
Accent chair: a single 18 inch pillow fills most armchairs and reading chairs without crowding the seat.
Seasonal swap: keep the inserts and store covers flat in a bin. Changing four covers takes five minutes and makes the whole room feel new.

Want cover ideas? See our guide to the best throw pillow covers and our living room refresh under $500 plan.

What to know before you buy

Sizing: same size or one size up?

Decorators often put an insert one or two inches larger than the cover (for example, a 20 inch insert in an 18 inch cover) for a fuller look. Using 18×18 pillow inserts in 18 inch covers gives a neat, tailored shape with less strain on zippers. If your covers are very loose or made of thick fabric, think about sizing up. If they are snug or have delicate zippers, the same size is the safer choice. Still unsure? Our sizing table explains what size pillow cover for 18×18 insert fits best.

Let them fluff up

Pillow inserts often ship compressed. Take them out of the packaging, shake and squeeze them from all sides, and give them several hours, or up to a day or two, to recover their loft. A few minutes in a dryer on no-heat or low heat with a couple of dryer balls can help them puff up faster. Check the care label before using heat.

Care and cleaning

Fluff your pillows every week or two by punching and shaking them so the fill does not clump. Wash removable covers often, and follow the care label on the inserts themselves. Pillows collect dust, so regular washing and vacuuming help keep the living room fresh; the EPA’s indoor air quality pages have simple tips on reducing dust and allergens at home.

Safety around heat

Like all fabric and polyester decor, keep pillows away from candles, space heaters and fireplaces. Do not stack pillows against a lamp bulb or a heat vent. Pillows are decor and lounging items, so keep extra pillows out of cribs and infant sleep spaces.

18×18 pillow inserts vs typical alternatives

Insert type	Feel and look	Care	Best for
Polyester insert with cotton cover (like these 18×18 pillow inserts)	Full, springy, rounded	Easy, follow label	Budget refresh, feather-free homes
Down or feather insert	Soft, slouchy, ‘chop’ look	Needs frequent fluffing	Designer look, sinking comfort
Down-alternative microfiber insert	Soft, a bit flatter	Usually washable	Bedrooms, light lounging
Foam or firm cushion	Firm, holds shape	Spot clean	Outdoor seating, back support

If you want a cheap, fluffy and feather-free filler for everyday covers, a polyester insert with a cotton shell is hard to beat. If you want that relaxed, sink-in look you see in design magazines, a down insert is worth the extra cost. For most busy family rooms, though, a pair of 18×18 pillow inserts like these is the practical choice.

See photos & price on Amazon →

How we researched the 18×18 pillow inserts

We did not test these 18×18 pillow inserts hands-on. We reviewed the Amazon listing details and specs, the brand’s notes on the cover and filling, how popular the listing is and its rating across many reviews, and we compared it with similar polyester and down pillow inserts. We update this review when the listing changes.

Helpful resources: EPA: Indoor air quality and NFPA candle safety.

18×18 pillow inserts: frequently asked questions

Are 18×18 pillow inserts worth it?

Yes, if your throw pillow covers look flat. New inserts are one of the cheapest ways to make a sofa look fresh, and you can keep using the same pair with new covers every season.

Should I use an 18×18 or 20×20 insert for an 18 inch cover?

An 18×18 insert gives a neat, tailored shape and is easy on zippers. A 20×20 insert gives a fuller, plumper look but can strain snug covers. Choose by how loose or stretchy your cover is.

How do you fluff pillow inserts that arrive flat?

Unpack them, shake and squeeze them from all sides, and give them a few hours to a day to expand. A short tumble on low or no heat with dryer balls can help; check the care label first.

Are polyester pillow inserts better than down?

They are different. Polyester is cheaper, feather-free and springy. Down is softer and slouchier but costs more and needs more fluffing. Pick based on the look and feel you want.

How do you clean throw pillow inserts?

Wash the removable covers often and follow the care label on the insert. Fluff inserts regularly and air them out in the sun now and then to keep them fresh.