Why Do Cookies Come Out Flat?

If you’re planning to sink your teeth into a thick, fluffy cookie, only to find yourself with cookie pancakes instead, you might wonder, “What happened? Why are my cookies flat?” While it was likely the butter that steered you in the wrong direction, there are a few other potential mishaps.

Hi, everyone! I’m Michelle, a self-taught baker that has an affinity for cookies. I love my cookies on the crispier side, but that doesn’t mean I want them to be flatter than a penny. 

Flat cookies are a common problem – even for experienced bakers like me, so don’t fret. The best thing you can do is pinpoint what went wrong, so you don’t make the same mistake twice.

With that in mind, let’s find out why your cookies came out flat (and how to fix them).

Why Do Cookies Come Out Flat After Baking? 6 Reasons

There are actually six potential issues that caused your cookies to go haywire. Luckily, they are all relatively simple solutions so that you can make a fresh batch of fluffy cookies in no time. 

1. The Butter Was Too Melted

The biggest reason your cookies might come out flat is using melted butter. Butter melts quickly in the oven, causing cookies to spread. But butter that’s melted before going into the range will cause overkill when it comes to spreading, leaving you with flattened cookies.

The best thing to do is let your butter sit at room temperature for about an hour before mixing your cookie dough. This will allow the butter to become pliable but not too soft or melted.

In a pinch and don’t want to wait an hour? You can use the microwave to soften rock-hard and cold butter, but you need to be extra careful. A second too long, and your butter will turn into a pool of golden goodness that will lead to flat cookies.

Be careful when using electric mixers, too. Butter can accidentally heat up if it’s mixed for too long. 

2. There Was Too Little Flour

Another main reason your cookies turned out flat is that you used too little flour. Flour soaks up liquid ingredients while mixing but will quickly release them in the hot oven. If there’s not enough flour, the liquid will overrule and cause cookies to flatten out.

Always use measuring cups and be precise. If your peanut butter cookie recipe calls for three cups of all-purpose flour, make sure you’re using precisely that amount – and not a pinch more or less.

While we’re at it, make sure you’re precise with all the measurements. Too much sugar can also have an impact on overall flatness. So, it’s better to leave “eyeballing” to the professionals and use your measuring cups and spoons.

3. You Used Hot Cookie Sheets

When you’re in the zone baking cookies, the last thing you want to do is take a 30-minute break in-between cookie batches. But pulling out a piping hot cookie sheet and using it for your next batch of cookie dough is a definite no-no.

Always make sure you’re using a room-temperature cookie sheet for your cookie dough. If you only have a single cookie sheet, let it cool for a few minutes before running cool water over it. Then, dry it off, and use it as usual.

4. The Cookie Dough Wasn’t Chilled

Now, not every cookie recipe calls for cookie dough to be chilled. If yours doesn’t, then don’t worry about this problem. 

However, if your cookie recipe calls for the dough to be chilled, there’s a reason. Don’t skip this crucial step, or you will likely end up with flatty patties.

5. The Leavening Agent Was “Dead”

A cookie recipe will almost always call for a leavening agent (baking soda, baking powder, or both). These leavening agents “puff up” your cookies, leaving them with that glorious thick appearance and fluffy texture.

But what you might not realize is leavening agents don’t last forever, even though it might seem like it. If you’re using an inactive leavening agent, your cookie won’t get fluffy – they will simply spread out.

To be on the safe side, consider replacing your leavening agents at least once a year. 

6. Oven is Too Hot

If you’re positive you used “softened” and not melted butter and added enough flour, but you’re still ending up with flat cookies, the culprit may be your oven. Ovens can say one temperature but be entirely different on the inside.

Try reducing the temperature by 5-10 degrees to see if you get different results. You might also consider investing in an oven thermometer to see what’s really happening in your beloved range.

How Do You Keep Cookies from Going Flat?

If you’re sick and tired of dealing with flattened cookies, consider incorporating these simple tips and tricks into your next batch:

  • Use soft but not melted butter
  • Make sure you’re measuring all ingredients correctly – especially the flour
  • Cool your cookie sheet in-between batches, or use a new one entirely
  • Chill your cookie dough before using
  • Use a fresh leavening agent
  • Double-check that your oven is reading the temperature correctly using an oven thermometer


Now you know how to fend off flat cookies for good. Are you eager to learn more about the flat cookie dilemma? Here are a few commonly asked questions you might want to check out.

Why are my cookies not spreading?

If you’re having the opposite problem and your cookies won’t spread, you’re likely using too much flour or too-cold butter. It could also be an issue with your dough being too chilled, an incorrect oven temperature, or too much leavening agent.

Should I flatten cookies before baking?

Unless your cookie recipe insists that you flatten the cookie prior to baking, then don’t do it. As I always say, it’s best to follow the recipe instructions entirely. If it tells you to flatten the cookie dough, then do it.

Can old baking soda cause flat cookies?

Old baking soda can definitely lead to flat cookies. It is imperative to make sure you’re using fresh leavening agents. You can check to make sure it’s active by pouring baking soda into a glass. Then, drop vinegar or lemon juice inside. If there is a fizzy reaction, it’s good.

Final Words

Cookies can come out flat for several reasons, and mishaps can occur from the mixing stage to the baking stage. As long as you follow the tips above, you shouldn’t have to worry about cookies coming out flat anymore.

Have you ever dealt with flat cookies? What did you do to fix it? Share your stories so we can try, too.

About Michelle
I have been a lover of sweets since day one. This led me on a self-taught baking journey starting at the age of 13. It's been over 10 years since the start of my baking adventures, and I’ve learned a lot along the way. Now, people rave about my delectable treats, whether it’s a chocolate cake or a strawberry crepe.

Leave a Reply

Your email address will not be published. Required fields are marked *

  • Cherie

    When adapting amish starter with regular molasses krinkle cookies , cookies flatten. I have added 2T flour. What should I do to prevent flattening?

    • Michelle

      It’s hard to say without seeing the ingredients and knowing how you baked the cookies. Have you tried any of my other tips for success?

  • Dav

    In the past 3 years we haven’t gotten anything but very flat cookies. This involved two houses and five different ovens. Until yesterday. We tried everythingfrom new ingredients to different measuring cups. We tried mixers and hand mixing. We even used our oil filled thermometer and calibrated every eletrick and gas oven. WHAT? The same thermometer calibrating every oven? It was the only common culprit in every baking session. So yesterday I lowered oven temperature from 350 to 310 and the cookies came out plump ad the problem was finally solved! The oil filled thermometer is no longer sold so I ordered a regular one and will check its calibration somewhat by the plumpness of the cookies, and recalibrate the 3 ovens with it.

    • Michelle

      Hi Dav!
      Wow, that’s quite an adventure. I’m so glad you were able to figure out the problem. Enjoy your plump cookies!