Barry Allen, a forensic scientist for the Central City Police Department (C.C.P.D.) was struck by lightning and bathed in chemicals which later granted him super-speed and the power to tap into the Speed Force (essence of speed).

Flash runs at the speed of light for sure, but it never mentions in the Flash series how fast he really is. If anyone knows the answer please tell me. I'm talking about both the new CW TV show "The Flash" and the comics.

  • 2
    No, he doesn't run at speed of light...
    – user931
    Dec 8, 2015 at 2:04
  • 2
    Are you asking about the character in general, or specifically the one in The Flash the TV show on the CW?
    – KutuluMike
    Dec 8, 2015 at 2:07
  • Im talking about both The TV show and the comic book
    – Luis Fucci
    Dec 8, 2015 at 2:09
  • You should alter the question to something like Flash's normal max speed as of some point in the continuity, because the answer otherwise is infinite, but he hasn't mastered it ever. Also sometimes the Flash pushes over what he'd normally able to do, but normally he'd never reach that speed. Kinda like normal humans and strength, If you're able to lift 100lbs, you're really able to lift 200lbs, but you're body normally limits you because lifting beyond a cetain limit will injure you too much. Same thing can be said of Flash.
    – Durakken
    Oct 14, 2016 at 1:07
  • related - scifi.stackexchange.com/questions/117886/… Nov 15, 2016 at 14:04

10 Answers 10


In the comics, Barry Allen has been shown to run faster than light, as per @Keen's answer to this related question. Exactly how fast has never really been measured -- as far as I know, they've never tried to apply the Star Trek "warp" scale to Barry.

In the DC universe, there are five "speed barriers" (really, critical velocities): the sound barrier, the light barrier, the time barrier, the dimension barrier, and the Speed Force barrier. Barry is one of the very few people who can break through all five barriers, meaning he can run significantly faster than light -- fast enough to travel into the Speed Force itself.

(In general, he rarely moves faster than a few Mach levels, because it causes major problems for his surroundings.)

In the TV show, we just don't know.

In the Flash episode "Legends of Today", Harrison Wells and Caitlyn Snow actually discuss Barry's top speed so far. Caitlyn claims that Barry was travelling at something around Mach 2 when he time traveled. (We have to assume, then, that the time travel is an effect of the Speed Force itself, and not a side-effect of supra-light travel.)

Wells claims that Zoom is "at least 10 times" as fast as that, and that Barry will have to get himself up to that point to face Zoom.

I think we can expect that as the season progressed, Barry will struggle to become faster than he has been up to this point, but there's no indication where that speed increase will happen.

  • 1
    Can you link to anything about him breaking the Speed Force barrier? That sounds awesome.
    – user31178
    Dec 8, 2015 at 5:38
  • I guess, running faster than light causes issues regarding seeing where you are going. Besides that, there is the issue of reaching your destination before reaching the top speed. Which raises the question about maximum acceleration…
    – Holger
    Dec 8, 2015 at 10:55
  • 1
    @CreationEdge Barry has been shown to enter the Speed Force; in Infinite Crisis he actually comes out of the Speed Force (when everyone thought he was dead) and grabs Superboy Prime and drags him in.
    – KutuluMike
    Dec 8, 2015 at 12:34
  • @Holger at that speed, Barry is entirely protected by the Speed Force, so he has none of those problems. But very bad things happen around him (imagine how much damage a sonic boom does, then multiply by a few billion).
    – KutuluMike
    Dec 8, 2015 at 12:36
  • I could be wrong, but shortly before the whole New 52 thing, didn't it turn out that Barry was himself the ORIGIN of the Speed Force? His life force scattered across time or something like that?
    – Omegacron
    Jan 14, 2016 at 13:12

Strictly from the TV show up to the point of Legends of Today, Caitlin Snow mentions his top speed quite accurately:

What's the fastest Barry's run?
Little over Mach two, when he ran back in time.

Taking Googles conversion that's just over 2469.6km/h or 1534.54mp/h

Mach 2 = 2469.6km/h and Mach 2.5 = 3087km/h. I'd say this is our top speed range, I'd assume over 2.5 would be more than a little over Mach 2.

  • 1
    Then there's scifi.stackexchange.com/questions/106289/… !
    – user31178
    Dec 8, 2015 at 5:38
  • Still, we have to be careful, since, like many writers, the The Flash writers seem to have a bit of trouble with basic math which led to this old question of mine (shameless self-promotion).
    – BMWurm
    Dec 8, 2015 at 11:08
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    @BMWurm I would say it depends on the character delivering the line, in your instance it seems more like a boast. Whereas in my quote it's a scientist talking about his top recorded speed. I understand where you're coming from though and as with CreationEdge above there are sometimes continuity errors. Dec 8, 2015 at 11:24
  • @CandiedMango I agree with you, that Barry was boasting there, although he is supposedly a scientist, too, being inaccurate should pain him as much as it should have pained Harry when he said "degrees Kelvin" [shudder] in 2x05 (but maybe they do that on Earth-2, so he might be excused).
    – BMWurm
    Dec 8, 2015 at 11:35
  • 1
    @MasonWheeler Yeah, probably the old foundry in Starling wasn't rusty enough ;)
    – BMWurm
    Dec 8, 2015 at 19:27

Well it really depends on the writer. In some i rember one time vs anti moinitor (not sure if that was spelled correctly) he had run 10 times the speed of light straining every muscle he had. In the CW tv series he tops off around mach 2. And the trillion times the speed of light the writer also said it was a hair under the speed of light. The writer got the math wrong. Anyways the point is Barry is faster than light in most situations but how much faster varies on the writers and in the tv show he tops off around mach 2 and even in the show he has feats which show him going much faster. For example when he saved Harrison Wells from a bolt of lightning. He was running 3-4 times the speed of the lightning. Lightning travels on average 220,000 mph. Much slower than light but much faster than mach 2 which is around 1500 mph


I just researched this. While I don't know if its true, I have found references that claim that in the comics he ran 13 trillion times the speed of light.

For reference, the speed of light converts to 186,282 miles per second.

In the TV show, he runs a little over mach 2 which is 0.426261 miles per second (according to google).

  • 2
    This is a pretty good attempt at the answer! I think you're mainly getting downvoted for a lack of references: how do you know that it's "13 trillion times the speed of light"? Or that it's over Mach 2? I really like your conversions!
    – Gaurav
    Dec 8, 2015 at 8:37
  • "13 trillion times the speed of light" is discussed in this forum: Flash max speed? Dec 16, 2015 at 6:21

In the CW show, Barry Allen has gotten exponentially faster. in the start of the show, when he ran down a tornado, he was probably running around 300 mph, because the fastest tornado on record was 318 mph, and a young weather wizard couldn't have matched that.

Later, in episode 6, he performs a supersonic punch, traveling at a bit over 800 mph. The speed of sound is 761 mph, and he was likely running a little faster to pull it off.

Closer to the end of season 1, he accidentally time travels while building a wind wall while fighting the other weather wizard. Barry claims on a treadmill he was replicating that speed, with the treadmill monitor reading at around 900 mph.

To artificially travel to the night his mom died, He was traveling over Mach 2, or 1500 mph.

In the middle of season 2, he managed to leap across a bridge, which was calculated at Mach 3.3.

When he acquired the tachyon splicer, he traveled "four times faster then ever before", which would calculate to around Mach 13.2.

Keep in mind that his top speed so far is only 0.0015% lightspeed, so he still has a long way to run. But after the events of "The Runaway Dinosaur", who knows what he is capable of now? Perhaps he is capable of running faster than even Zoom!

Zoom originally traveled at around the speed Barry could achieve through the Tachyon device. Now that his powers have doubled, Barry would have to run at 0.003% lightspeed, around Mach 27, to beat Zoom. This would be like trying to outrun a space shuttle taking off. Interestingly enough, if Barry takes all of Zoom's Speed (I think he might at the end of the season), then he could become faster than Voyager 1, the Fastest man-made object ever, currently traveling at Mach 50. Interesting!


So the question we're trying to answer here is how fast the Flash's top speed is right? If that's the case then there's actually a lot of ways to answer this question. In Flash: The Human Race, the Flash was able to beat instantaneous teleportation by absorbing the kinetic energy of everyone on Earth. By going this fast, the Flash ran faster than a planck instant therefore breaking what we call "speed" and "time". A planck instant (called planck time in real life) is the smallest unit by which we measure time and speed. So when the Flash ran this fast, he was everywhere and nowhere at the same time.

So to beat instantaneous teleportation, the Flash had to go faster than a planck instant which leads me to say that instantaneous teleportation has to be a little slower than the speed of light.

Before I get into more, I want to say that teleportation does not equal moving at high speeds, it's the transfer of information from point A to point B. This transfer, although seen as instantaneous, will still take time.

Moving back to what I was saying before, teleportation is not faster than light. Einstein says that no information can travel faster than the speed of light. It's just not possible.

But we go back to the Flash, he runs faster than a planck instant which is way faster than light. This is possible for two reasons: 1. It's a comic 2. He is not actually transferring info. He's just running faster than light by tapping into the Speed Force and absorbing the kinetic energy of all the people on Earth

So there's my opinion on the Flash's top speed. However, we can also argue that the Flash doesn't really have a speed cap because there will always be the Speed Force. It literally says that since Barry Allen created the Speed Force and generates it with every step he takes, he can "reach any speed he imagines". If he wants to go faster than he just needs to generate more speed (sounds dumb and obvious, I know). The Flash's speed cap is therefore, unknown. We do know that he doesn't like to run faster than Mach 10 (7672.69 m/h according to google conversions) in Earth's environment because the results will be catastrophic.

Just to let ya'all know, it was Wally West that ran faster than a planck instant not Barry Allen.

Also here's a list of some conversions:

Mach 2- 1534.54 m/h

Mach 10- 7672.69 m/h

SoS- 767.269 m/h (343 metres per second)

SoL- 671 million m/h (exact value is 299,792,458 metres per second)

Planck Instant- Undetermined. This is unable to be measured by the current technology that we have today. "As of May 2010, the smallest time interval that was directly measured was on the order of 12 attoseconds (12 × 10−18 seconds), about 10 24<---this is suppose to be an exponent) times larger than the Planck time."- Wikipedia


That's not really his speed in one the comics it was stated he wasn't running because he reached Trans time speed which means he can reach anywhere anytime.

  • 2
    Welcome to the Science Fiction and Fantasy Stack Exchange. We appreciate you taking the time to attempt to answer a question. However, you answer feels a little vague and could do with a bit of differentiation between the comic Flash and the recent television Flash. This might help the Original Poster (OP) to better use your answer. Include any references or screenshots you think might help your case. Welcome Aboard. Mar 19, 2016 at 3:35

I think flash will just keep getting infinitely faster. When he travels back in time as a lightning bolt and strikes himself in the comics, he will eventually get faster than he was then. The process starts itself over.


Barry Allen in the comics can go as fast as he wants to, he is the source of the speed force and generates it with every step he takes making him the fastest speedster

  • 1
    Welcome to Science Fiction and Fantasy, and thanks for your first post. Do you have a source for this answer? Answers benefit greatly from sources: comic pictures, descriptions, even wiki quotes. This will help people not familiar with the material assess the validity of the answer’s arguments.
    – Adamant
    Oct 4, 2016 at 0:59

wall west isn't faster then Barry Allen here is why i say this in the comics Barry Allen was able to outrun Death multiple times while the cannon Kid Flash (wally west) died in a way like he did in Young Justice he was going too fast for his body to handle and disintegrated. and in TJL (The Justice League) he was able to run around the world in less then 10 seconds and literally beat brainiac off of Lex Luthor.

  • 1
    This is not an answer to the question. It appears to be a comment on the answer by Met Rodgers.
    – Blackwood
    Oct 14, 2016 at 1:27

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