We have five I think. The best parenting tip I got was to do layers of bedding so it goes like this:

mattress
waterproof cover
fitted sheet
waterproof cover
fitted sheet

If there's a diaper explosion or spit up in the middle of the night you just strip off the top sheet and waterproof cover -- no need to make the bed in the middle of the night. If our daughter is really sick sometimes we add another layer as back up. The last thing I want to do in the middle of the night is fumble for clean sheets and struggle to make the bed!

And it doesn't make the bed "warm" or anything like that, we've done this for 4 years and it's been a lifesaver.

I have 3, and it was enough for the past 18 months...until my poor baby got a stomach bug. We went through all the sheets in one night! But I think with an infant, if you use lap pad or something akin to them, you can get away with just a few. I have seen the kind that have ties on them so that you can tie them to the bed. Wish I would have had those the other night...

Two and although it was recommended to us, we've never done the layering thing.

I agree with the layering technique! I also recommend IKEA's crib sheets; they are not fancy or organic or anything but they wash well, fit well and are inexpensive. A great option to have some extras for back-up. I think they are $9.99 for 2.

I think I have 4 regular ones and 2 flannel ones. Absolutely need to use the flannel ones in the Winter here in Michigan! A friend of mine swore by the layering technique, but her kid was a constant puker.

I have two in cribs/toddler beds and have seven sheets which is more than enough. Most are knit cotton ones that work great and all my favorites (knit and woven) come from Ikea of all places.

We've survived with just 2 fitted sheets during the last two years but we've been pretty lucky that our boy hasn't been sick or had a diaper accident in that time (ok...he once got sick and we ended up having to put him in the travel cot)

I really like the layering idea, though. I think we'll have to try that when my son starts potty training (if he's EVER ready!!)

I have 8, but only because my oldest had a tendency to spit up ALL the time. Two of these are minkee fleece and I use those the most.

I have two, one I bought and one I made (incredibly easy, by the way! even for novice sewers, google Prudent Baby Crib Sheet for easy instructions).

I wish I had another waterproof mattress pad though, only having one gets us in trouble if there is a leak!

That being said we have survived 10 months with just one, so maybe that's ok. :)

We have two fitted sheets and really only need one. We bought two ultimate crib sheets (snap on, waterproof layer) and rotate them through the wash. I only changed out the fitted sheet below once when I got tired of the pattern of the first showing through the side of the crib. Two ultimate crib sheets is usually enough to get through a bad night.

Completely agree with QueSrah, I wash the fitted sheet once in a blue moon, and 2 ultimate crib sheets have gotten us through 2 babies!

We have four (three purchased, one was a gift) and two waterproof pads. During one horrible night, we did use three of the four sheets and both pads. We've never had the need for the layering technique although I kept meaning to do it. :)

We have three sheets and one matress cover for the crib & that seems to have worked just fine for us so far (we have a 14 mos old girl). Changed em more in the beginning when more leaks/spitups happened. We did have a lot of bassinet sheets, none of which we bought by the way. We were loaned a bassinet that was the ugliest thing ever, but a lifesaver and for long we used it (maybe a month) I was very happy I hadn't wasted the money on one! And, I passed it on (along with the sheets!) when I was done. Another situation though, where you only know when you know ;)

Just two and it has worked fine for me. In fact, I ended up liking one better than the other, so I usually just wash it during the afternoon and put it back on before bedtime--don't even switch them out!

I have three and that's been plenty. For baby #2 I think I'll only buy 2 (changing genders!).

We have 3 sheets that have served us well as accidents have been rare. My son didn't really spit up, and so only one set was puked upon, by my husband, as he changed a diaper!

We done different things depending on our parenting style du jour.

For our son on the toxic waterproof vinyl covered mattress wearing disposables we just used a sheet with nothing else. If we had an accident we just wiped it off the bed and changed the sheets. We have 3-4. I like cotton knit.

For the co-sleeping baby/toddler in cloth diapers and woolies (super absorbent), we just had a thick cotton “waterproof” layer she slept on in our bed.

For the potty learning toddler wearing underwear with a PUL cover, sleeping on an expensive natural mattress without plastic cover, it goes mattress, wool mattress cover, cotton waterproof barrier (2), sheet. We’ve needed to change the waterproof barrier and sheets a few times but only needed to clean the wool mattress cover as part of general cleaning.

None of my kids spit up though and I think we’ve had a single stomach virus ever (3 sheets + 2 towels + six pants all in a hotel) but occasional upset stomachs.

We have 4, two that match our crib set and 2 extras. We also have 1 rubber sheet/matress protector and we layer them for quick bed changes.
Rubber sheet
Fitted sheet
rubber sheet
fitted sheet
Now that my son is in a toddler bed with a crib size mattress that set up is particularly helpful for middle of the night accidents.

I bet we have at least a dozen. My 18 month old has had severe acid reflux since she was an infant and it's not uncommon for us to have to strip her sheets two or three times a day. But my understanding is that is not normal. :)

We have 5-6 which is sometimes not enough since we are only able to do wash once a week (but that covers beds for two kids, one of whom is potty trained but will occasionally wet the bed at both nap and night). If you are able to throw in a load of wash daily as needed and have one bed, 2-3 would be more than enough. Even with a spitty baby and leaky diapers, we managed with just 2 sheets while I was on maternity leave.

I had 5 with both of my kids. I never needed that many with my first one. Then I had Topper. There were lots of nights of changing numerous times.

I always tell my friends, "You don't need them, until you need them."

We have 7+ because we have twins so I have two beds to do. I never did the layering thing either, but when the girls were really little we put a pad on top of the sheet and they slept on that. It was when they started rolling that we pulled it out. This way if they spit up, peed/pooped through then it was just changing the pad, not the sheet. Now at 22 months we change sheets every week to week and a half instead of almost every other day!

For most families (with access to a regular washer/dryer), 3 is probably fine--one in the hamper, one on the crib, and a spare in the drawer. After 4 kids, this was all I've ever needed. I didn't change them religiously, just when needed (spit up, leaks, etc.) and this worked out just fine for us.

And on an environmental note, it's always good to start out with the basics rather than wasting resources. If you end up having a particularly messy baby, you can always add later. But stockpiling for "maybes" is just a waste with all baby things.

We have 3. 1 for use, 1 for wash, and 1 just in case.

For my son, I have 2 regular and 2 flannel which are wonderful in the wintertime especially at our old home which his room was the coldest since it was over the garage. Now with my daughter, I techincally have 4 but 2 shrunken so much that they are getting used as rags and the other two are from IKEA which are now my favorite ones (why didn't I just buy them all from there). I will most likely be buying two more flannel ones from her because I have a feeling my son will still be in a crib/toddler bed this winter. Each kid has 2 mattress pads and so far we haven't ever really needed more.

I have 10. For a while there, I had two kids in cribs at the same time. I don't layer, but I do "double up". When I make the bed, I put a mattress pad and a sheet on the mattress, then I flip it over and repeat on the other side. That way if we need to do a quick change in the middle of the night, I just strip the sheets off one side and flip the mattress over.

I had thought 3 for each kid would be sufficient, and then we had the stomach bug from hell. ;)

Three fitted sheet and one waterproof to protect the mattress. One of them I bought in LA while visiting my sister, as I wouldn't bring any from France just for ten days. It was so cute I brought it back though.

I found two is what I need for my boy; but if we ever have a girl, I'll probably buy new ones, since I'll reuse the crib and everything. Sheet dress the bed so prettily that I use them as a major decorative element. And since I use pieces of furniture I already have, I can splurge on bedding.

I had 4, but really only needed 2. Neither of our kids pikes ot wet the bed, and we didn't bother layering.

We used pottery barn sheets -- solid chambray and gingham for summer, and Chamois for fall and winter.

I have a waterproof mattress cover, 2 regular IKEA sheets, 2 flannels and one I just got recently that feels like a t-shirt. I hope it's enough. My baby should arrive any day! I didn't bother with a crib set at all.

We have 2, but DD co-slept until a year, and then 2 always seemed fine. I'm thinking we'll need 2 flannel sheets for our winter baby though.

err, that darn autocorrect on the iPad...

That would be -- "...neither of our kids puked or wet the bed".

Just in case, we had a hospital-quality "peri pad", but fortunately, never needed it. It really depends on the baby in question; you may need more. Start small, with 2, and see how it goes. It's easy to buy more, but a waste to buy too many.

Rather than having to switch the whole sheet in the case of a spit-up, we have a receiving blanket tucked over the area where the baby's head is. Much smaller to wash than a fitted sheet and you're likely to get a bunch of them as presents anyway.

We had four crib sheets with our daughter - two flannel, and two regular cotton. The flannel was definitely a necessity for us living in eastern Canada! We found that was enough for us.

I have 4 for 2 beds--one crib (17 mo.) and one toddler (4 yrs.). Never needed more save one night with the oldest before the younger was born. She had the flu and we went through everything. Ended up using tablecloths, but she was old enough where it wasn't a suffocation hazard at that point. I always wash immediately, so there are 2 waiting, and we've been fine. But, my kids aren't pukers or particularly prolific from the other end, so it works.

I had 4 with each baby: 2 jersey cotton for lighter summer months and 2 flannel for the winter. My kids never seemed to have night-time disasters, only day-time disasters, so that was always enough. When my younger son was born, I discovered these truly awesome sheets made by carters that are this fabulous lux-velour stuff so I had to splurge on a couple of those for him since he was such a snuggly kid.

Apologies for being off-topic here: @nellymom... you're still going with the reflux at 18 months?! My son is 10 months now and I feel like the spitting and discomfort will never end. But everyone tells me he should outgrow it by a year...

As for sheets, I have 3 that I share between two kids. But we need more. I think 6 total would be ideal for our setup.

2 for one kiddo and it's worked well. We have one to put on while the other is in the wash. Even got us through a stomach bug. I have thought about getting a flannel for winter, though.

I'm contemplating whether I need 3 or 4 to share between my daughter and her coming sister. So this was a very timely post!

2 waterproof mattress pads
2 crib sheets
2 sheet savers

My kids are now 4 and 5 years old. I have always a waterproof sheet over the mattress and then above this sheet a cotton crib sheet. That´s enough in my opinion. To change you need one or two, better two more crib sheets. If your kid gets a stomach bug, you will be happy to have more than only one to change. But, you can also use a towel if you have used up your bed sheets. I bought 3 for my crib and it was enough for the first month (mattress size 50x100cm), than I changed the bed to a mattress size of 70x140cm and bought 3 sheets for that mattress. But suddenly everyone thought I could need bed sheets and I got second-hand/used sheets from different moms and at the end I had +/- 20 pieces. O_O So I had never problems with stomach bugs. But if I had to buy them, I would buy 3 or 4 and check If I have some towels (bath or shower towels) in a big size, than I can use or some other oft fabric.

If you have more than one baby/kid, and they go through a stomach bug, think about the not so unrealistic possibility that both kids have it the same night (we hat that lucky situations twice^^) and than you will need 4 sheets or more. :)

(Sorry for my bad English, I´m not a native speaker and haven´t used my English since years). :)

We have 8. But I have twins so it's really 4 each. Now that they're almost 2 it's too many but those early spit-up/leaky diapers days we could easily go through 2-3 for each kid in 24 hours. Switching to cloth diapers helped with the leaks.

We ended up not changing the sheets so often because we had some awesome flannel waterproof pads to put on top of the sheet. The flannel grips the sheet and stays in place. And we got huge ones that covered the whole crib. I had to swap that out at night for one reason or another, but never had to change the sheet.