Newer Post . 
Also, take into consideration what type of fill youll be using- if its something more firm, Id stick around a 2" increase, if youre using something with more give, like down/feather, Id go closer to 3-4". xx, sized insert, you want to make sure that you are putting, your pillow cover properly. 
Older Post For example, for a 13x34 cover. 
guides should really be a fool proof way to plump up your pillows! Ive built my recommendations based on a mid point, so if you really love a soft, relaxed look, you may want to shave off an inch or two. January 22, 2020, HOW TO SIZE YOUR PILLOW INSERTS Hi Ray, I would definitely recommend sizing up 2-4" on your inserts at that size. but mainly on the longer side. 
The above guides should really be a fool proof way to plump up your pillows! Small Square (17x17 and smaller): Size up 1 for your insert size. 
WARNING: you may have a strong craving for tacos after watching it. For a 17"x17" size cover, use an 18"x18" insert. You've bought your pillow cover, but, now what?! ), SIZE GUIDE - SQUARES(you can find any of these sizesHERE). I think you could possibly get away with doing an 1818 insert, if you like a more relaxed fit and more of a chop. I can show you how to do that in a few minutes, This is a huge factor that also comes into play!! I useTHESEall the time for my 22"x22" covers. 
It should be a good starting point! Extra Large Square (26"x26" and larger): Size up 3-4" for your insert size. 
I've referenced down/feather inserts only, because they have more "give" than firmer polyester or down alternative inserts. For a 22"x22" size insert, use a 24"x24" insert. 
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While you can still size up on down alternative inserts, I'd lean towards sizing up at a rate of about half of what I've given above. 
Its completely personal preference. I can show you how to do that in a few minutes HERE. Large Square (22x22- 24x24): Size up 2-3 for your insert size. 
I'm so excited to give you my tried and true recommendations! For an 18"x18" size cover, use a 20"x20" insert.
While I usually wouldn't recommend sizing up this much, the fill isn't has heavy as most manufacturers, so it fills more like a 24"x24" insert. I would err on the side of a larger insert, rather than smaller, when choosing inserts for your 24"x24" pillow covers (go up 2-4" depending on your fill preference- soft or firm)! You can read more about it HERE! P.S. Hi Kirsten, you should be fine using a 1620 insert for that size if thats all you can find! 
And, the larger the size of your pillow cover, the more you are going to want to size up. 
You can read more about it, Design: Eye for Pretty || Photo: Amy Bartlam, Design: Harlowe James || Photo: Torrey Fox, Design: Veneer Designs || Photo: Marisa Vitale. While you can still size up on down alternative inserts, I'd lean towards sizing up at a rate of about half of what I've given above. Which means that whatever size your pillow cover is, you need your insert to be larger than it! I've referenced down/feather inserts only, because they have more "give" than firmer polyester or down alternative inserts. Do you still recommend upsizing for an 1818 
Next uphow pillow sizes look on certain pieces of furniture and sizing/grouping recommendations! all the time for my 22"x22" covers. (Boho Pillow is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking toamazon.com. Small Lumbar (11x19-11x23): Size up 1 on, , using a 12x20 and 12x24 insert respectively. But, as you start getting into bigger sizes, you have to find a trusted manufacturer.
I, no one size fits all. You can usually get away with a lower fill weight on smaller sizes, as you really wont notice it as much. Large Lumbar (13x34- 18x48): Size up about 2-3 on these. 
The bottom line is that every manufacturer fill weights are different, and there is unfortunately no one size fits all. You can usually get away with a lower fill weight on smaller sizes, as you really wont notice it as much. P.S. or order a few sizes to see which one is the best fit. While I usually wouldn't recommend sizing up this much, the fill isn't has heavy as most manufacturers, so it fills more like a 24"x24" insert. You may have to finesse your insert sizing for 22"-24" square pillow cover sizes, as manufacturer fill weight differences become more noticeable on the larger sizes. P.P.S. To help it live its best pillow life possible, I really want to help you easily determine what size inserts you should buy for your pillow covers! Hi there, But, as you start getting into bigger sizes, you have to find a trusted manufacturer to use, or order a few sizes to see which one is the best fit. Hi Bridget! But now not sure what size pillow covers I need for my pillows? 
As a general rule, the smaller the size of your pillow cover, the less you have to size up on your insert. February 28, 2018, Sign up and be the first to know about upcoming sales + new products!! The one thing you ALWAYS want to do, is size UP on your insert size. Medium Square (18x18-20x20): Size up 2 for your insert size. You may have to finesse your insert sizing for 22"-24" square pillow cover sizes, as manufacturer fill weight differences become more noticeable on the larger sizes. I would err on the side of a larger insert, rather than smaller, when choosing inserts for your 24"x24" pillow covers (go up 2-4" depending on your fill preference- soft or firm)! 
Otherwise, it is, !! I use. I've used, Medium Lumbar (14x22- 15x23): Size up 1-2 on, , a 16x24 down/feather insert usually works well on these sizes. I think a 1919 insert could be a happy medium if you can track one down. 
thank you! 
It can be a confusing world, with sizing nuances from every manufacturer, knowing what to size up on, how much, etc.
I dont suggest overfilling your pillow covers too much, you will put more stress on the seams and it could stretch out the fabric over time. 
In case you missed it above, I tested 5 manufacturer's pillow inserts to give you the low down on the best bang for your buck! In case you missed it above, I tested 5 manufacturer's pillow inserts to give you the low down on the best bang for your buck! For a 22"x22" size insert, use a 24"x24" insert. 
use a 14 (sized up 1) x36 (sized up 2) insert, Large Square (22x22- 24x24): Size up 2-3 for your insert size. According to the tag, my pillow inserts are 2424 inches. This is a huge factor that also comes into play!!
I use. And, if you ever need a suggestion for a size not covered here, please dont hesitate to contact me! January 31, 2020, WHERE TO BUY THE BEST PILLOW INSERTS
It may be more firm, it may be OK, it seems most lumbar sizes are not too overly filled. And do the opposite for firm, but only add an inch or so. Once you've found the perfectly sized insert, you want to make sure that you are putting it into your pillow cover properly. You could get away with 2 more on the longer side, but I wouldnt go more than that. July 03, 2018, STUFFING PILLOWS (THE RIGHT WAY)!! 
Please note, comments must be approved before they are published, NEUTRAL PILLOW COMBOS I like a visible dent in the top of a throw pillow.
April 07, 2018, HOW TO MIX PILLOWS LIKE A PRO I broke down 5 pillow manufacturers' inserts HERE if youd like to see the results! I was about to get 2424 covers.but now see that, that wouldnt be correct.
Otherwise, it is not going to matter how good your insert is!! Your preference on the softness or firmness of your pillows will also come into play. What size pillow covers / cases would I need? 