<p>Usually they can get is <strong>Almost twice</strong>.  Here's the evidence:<br>
 It is difficult for them to become even bigger than that as once they reach 15 Jupiter masses or so there is enough pressure in the core to ignite deuterium fusion, so those are considered “brown dwarfs” rather than planets.<br>
An example is TrES-4, which is located 1,400 light years away in the constellation Hercules. The planet has been measured to be 1.4 times the size of Jupiter, but it only has 0.84 times Jupiter’s mass. With such a low density, it is dubbed <strong>the puffy planet</strong>.<br>
It was discovered in 2006 orbiting a brightish star 1500 light years from Earth. Its diameter of about 1.8 times Jupiter’s makes it the largest accurately measured planet. Strangely, though, TrES-4 is very light for its size. It has only 88 per cent of Jupiter’s mass, giving it a density of roughly 0.2 grams per cubic centimetre, less than that of cork. Just how a planet can be as fluffy as TrES-4 remains a mystery.</p>

CC BY-SA 3.0
2017-05-16T02:30:25.230Z
The largest planet is not Tres-4b. WASP-17b and Kepler-435b are both claimed to be larger.
ProfRob
CC BY-SA 3.0
2017-05-16T06:16:30.250Z
Well u pointed out. I had old source saying Tres-4 is biggest. i shall update soon.
pooja somani
CC BY-SA 3.0
2017-05-15T18:14:24.010Z
2017-05-16T06:26:51.383Z
2017-05-16T06:26:51.383Z
pooja somani
<p>What is the maximum size for a gas giant? </p>

CC BY-SA 3.0
2017-05-15T17:34:42.540Z
Also highly related, [Are gas giants supported by thermal pressure?](https://astronomy.stackexchange.com/questions/17866/are-gas-giants-supported-by-thermal-pressure)
David Hammen
<jupiter><gas-giants><size>
Why could a gas planet not get much larger than Jupiter?
Rayn
# Why could a gas planet not get much larger than Jupiter?

(Asked by: username_0 on 2017-05-15)

What is the maximum size for a gas giant?

**Tags:** jupiter, gas-giants, size

> **Comments:**
> **username_1**: Also highly related, [Are gas giants supported by thermal pressure?](https://astronomy.stackexchange.com/questions/17866/are-gas-giants-supported-by-thermal-pressure)  

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## 1 answers

### Answer by username_2 on 2017-05-15. Score: -1

Usually they can get is **Almost twice**. Here's the evidence:  
It is difficult for them to become even bigger than that as once they reach 15 Jupiter masses or so there is enough pressure in the core to ignite deuterium fusion, so those are considered “brown dwarfs” rather than planets.  
An example is TrES-4, which is located 1,400 light years away in the constellation Hercules. The planet has been measured to be 1.4 times the size of Jupiter, but it only has 0.84 times Jupiter’s mass. With such a low density, it is dubbed **the puffy planet**.  
It was discovered in 2006 orbiting a brightish star 1500 light years from Earth. Its diameter of about 1.8 times Jupiter’s makes it the largest accurately measured planet. Strangely, though, TrES-4 is very light for its size. It has only 88 per cent of Jupiter’s mass, giving it a density of roughly 0.2 grams per cubic centimetre, less than that of cork. Just how a planet can be as fluffy as TrES-4 remains a mystery.

> **Comments:**
> **username_3**: The largest planet is not Tres-4b. WASP-17b and Kepler-435b are both claimed to be larger.  
> **username_2**: Well u pointed out. I had old source saying Tres-4 is biggest. i shall update soon.  

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