How Fast Is The Flash?

For now, the Flash's top speed is 13 trillion times the speed of light.

By Jonathan Klotz | Updated

grant gustin the flash

The Flash is the fastest hero in the DCU, which is a well-understood fact, even if different villains appear with more speed; eventually, Barry Allen is able to surpass them. For all of his strength, Superman can’t beat Allen in a race, which has happened multiple times in the comics. To figure out exactly how fast the Flash can run, we have to look at the Arrowverse version, starring Grant Gustin, and pull out some higher-level math, but it’s safe to say he’s capable of exceeding the speed of light.

Over each season, The Flash’s top speed has expanded, as now the old benchmark established in Season 2, Episode 18, “Versus Zoom” of Mach 13 has been exceeded. Converted to miles per hour, Mach 13 is 9,974.5 miles, which is hypersonic speed and sounds impressive, but that’s still under the current mark of the fastest humans have traveled. The crew of the Apollo 10 achieved a record of 24,816 mph when re-entering Earth’s orbit on May 26, 1969 (via Guinness World Records), so if Barry Allen keeps getting faster, can he beat the real-life record?

The Flash, Season 2, Episode 18 “Versus Zoom”

The answer is both yes and no. Using his superhuman powers, The Flash has a set limit to how fast he can run. Still, unlike how Superman and Wonder Woman generate their speed, Barry Allen has a separate source of power, The Speed Force. Tapping into The Speed Force allows Allen to go beyond his limits, and as his connection to the extra-dimensional source gets stronger, he gets faster, eventually reaching the point that he can breach universes.

By the time Season 4, Episode 12 rolls around, The Flash’s top speed allows him to take an inmate from Iron Heights to Jiaju, China, without appearing to move according to the fixed security camera. In order to cover the 7,480 miles between Central City (assuming it’s the DC version of Kansas City) and Jiaju, Barry had to run at Mach 155,096, or 119 million mph. That’s 4,795.29 times faster than the Apollo 10’s re-entry, and yet, still not his top speed.

The Flash, Season 6, Episode 1, “Into the Void”

After continuing to bond with The Speed Force, The Flash achieved a speed so great he was able to run into a black hole. Barry Allen achieved this latest feat in the first episode of Season 6, “Into the Void,” approaching the speed of light for the first time in his career. That means sustaining a speed of at least 670.6 million mph (or Mach 874,031) for over 30 seconds in order to prevent the immense gravity well from crushing him instantly.

The speed of light is 186 million miles per second in the cold vacuum of space, and it’s considered to be a universal speed limit; nothing can go faster, according to Einstein, and no one has been able to prove his calculations wrong. Well, that’s true in the Arrowverse, as The Flash’s currently calculated top speed is still well below the speed of light, as even going into the timeline or other dimensions required a speed far below 186 million miles per second. 670.6 million mph is the top speed of Grant Gustin’s version of Barry Allen in The Flash, but what about Ezra Miller’s version in the DCU?

For now, there’s less evidence to draw from, so we’re forced to rely on Justice League, which shows Henry Cavill‘s Superman can achieve Mach 27.5 (21,099.9 mph), and Ezra Miller‘s Flash is going slightly faster, achieving a likely top speed of Mach 28 (21483.5 mph). When The Flash premieres next month, the speed on display will likely go well beyond that benchmark, but for now, it puts the DCU Flash as the slowest version of the character. After all, the live-action versions of the character are derived from comics, and it’s within the pages of DC Comics that Barry Allen is at his fastest.

The Flash: Rebirth #4

Barry Allen as The Flash in DC Comics created The Speed Force, which gave all of the other speedsters their powers, from Jay Garrick to Wally West. The comic version of The Flash is so fast that his top speed generates a multiversal constant power, existing in every time and dimension. In practical terms, even in the comics, Allen is restricted by the speed of light, only achieving 186,000 miles per second as his top speed.

JLA (1997) #89

However, Barry Allen is not the only Flash, and in the pages of DC Comics, it’s Wally West that reigns supreme with the highest possible top speed. In JLA (1997) #89, Wally West saves the entire population of a city from a nuclear explosion and in doing so, achieves a higher top speed than any other Flash. Crunching the numbers to carry 250,000 people to a safe radius means that Wally West was running at 13 trillion times the speed of light.

Wally West as The Flash can run 2.5 quintillion miles per second as his top speed. That is significantly faster than Grant Gustin’s Barry Allen in the Arrowverse and even the DC Comics version of Allen. It remains to be seen what Ezra Miller will accomplish in his upcoming film, but for now, the fastest Flash can outrun the speed of light by 13 trillion times.