RAM 2500 DEF Tank Size [With Tips To Identify Tank Size]

What is Dodge RAM 2500 DEF tank size? For the 2014 to 2020 edition, the DEF tank size was between 5 – 5.5  gallons. And after 2020, the DEF tank size comes in different sizes for different models.

In this article, you will know the details of the tank sizes of RAM 2500 according to different models.

Additionally, we will provide you with some extraordinary guidance about filling the DEF tank given by our experts.

So! We will recommend you to pay proper attention and read the article until the end without skipping any part.

RAM 2500 DEF Tank Size

RAM 2500 refers to heavy-duty pickup. Every DEF tank of RAM 2500 is slightly different for every model.

Nevertheless, the DEF tank for 2014 to 2020 is quite similar. In 2015 it was 5.5. Then the 2016 to 2020 Dodge RAM 2500 DEF tank size is reduced and comes to approximately only 5 gallons.

After the 2020 version, the DEF tank size does not increase much. Yet there are some differences in the DEF tank size for different types.

 Let me present to you a table of Dodge RAM 2500 DEF tank sizes according to the various year’s models.

Table for DEF Tank Size of Dodge Ram 2500

Year Of RAM 2500DEF Tank Size
2014-2020 RAM 25005 – 5.5-gallon tank  
2021 tank 2500  5.14-gallon tank (Rebel) 5.74-gallon tank (Others)
2022 RAM 25005.14-gallon tank (Tradesman)

Description For Different DEF Tank Sizes

From the table, you can see most of the RAM 2500 has a tank size of 5-gallon. 

But the 2015 RAM 2500 DEF tank size is not 5 gallons. It has a 5.5-gallon tank. That means the 2015 version needs 5.5 gallons on the pickup.

After great research, our professionals say, ” One gallon of DEF can last for 895 miles.” 

So we can inform you that the 2016 RAM 2500 DEF tank size requires a faster fill-up than the 2021 RAM 2500 DEF tank size. The DEF tank size in 2021 is slightly bigger than in 2016.

You need to fill up a DEF tank with the 2017 RAM 2500 DEF tank size every third or fourth time of fill-up. Because it has only 5 gallons of DEF which can run roughly 4000 miles.

Most of the Dodge has the same lasting pattern for 2014 to 2020. So, you should fill up your DEF tank a fourth time.

In 2022 RAM 2500 DEF tank size for the Tradesman model is 5.14 gallons. So we can also become sure that the DEF tank filling time is the same as before 2020.

For the 2021 RAM 2500, there are some models available. In these models, the Rebel has the largest DEF tank among all DEF tanks. Not only from 2021’s models but also from before 2020’s models like the 2018 RAM 2500 DEF tank.

Now that you know when you need to fill the DEF tank we will try to make you understand when you should stop.

When Should You Stop Filling DEF?

If you fail to identify when you should stop filling DEF into the DEF tank, there will arise various problems. The problems include overheating, overflow, engine failure, sticky-ness, etc.

So here we come with some signs that will ensure you that you do not need to fill more DEF into your DEF tank.

  1. DEF squirts out of the filler neck.
  2. The DEF pump nozzle shut off automatically.
  3. DEF stops flowing into the DEF tank.
  4. Increase the weight more than the tank can hold.

Frequently Asked Questions (FAQs)

How much DEF fluid does a RAM 2500 use?

A RAM 2500 uses approximately 1 gallon of DEF fluid per 1000 miles. That means you can run 1000 miles with 1 gallon of DEF fluid.

How many gallons does my DEF tank hold?

For the RAM 2500, your DEF tank can hold around 3 to 5 gallons. And for RAM 3500, your DEF tank can hold about 8 gallons.

Does “Towing” use more DEF?

Yes, towing uses more DEF. The reason is towing adds more weight, more weight needs more fuel to burn. So the requirement for DEF also will increase. For towing the DEF increased by about 1.5 to 2%.


The DEF tank sizes are quite similar for all RAM 2500. We try to give you a proper guideline about the RAM 2500 DEF tank size

We hope the table of different sizes of different years’ RAM 2500 can be extremely beneficial for you to easily and rapidly understand the DEF tank sizes.

Moreover, the tips for when you should stop filling the DEF will help you to ensure your DEF tank size.

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