How Hard Does the Average 13-Year-Old Throw?

About 65 mph, and that is a real jump from age 12. The leap is mostly growth, and it brings a temptation worth resisting.

4 min read·1 cited sources·Last reviewed June 17, 2026

NC By Nathan Critchett, Founder of CritchPitch

The quick take

The average 13-year-old pitcher throws roughly 65 mph, a notable jump from 12U.
Most of that jump is puberty and growth, not training.
The danger at 13 is chasing the velocity surge with more throwing, showcases, and breaking balls.
This is a prime age to protect the arm, because workload is climbing right as the body changes.

The short answer

~65 mph

The average fastball for a 13-year-old (13U) pitcher, a meaningful step up from the roughly 55 mph average at 12.¹

Thirteen is often where the radar gun jumps, and it can feel like the training is finally paying off. Some of it is. But most of the leap from 12 to 13 is simply growth, as kids hit puberty, add size, and get stronger almost for free. That is worth knowing, because it shapes how you should respond to it.

Why 13 is a turning point

The velocity surge at 13 tends to bring three temptations at once: throw more, start hitting showcases, and add a breaking ball. Each one feels like the natural next step. Together they are exactly the recipe that the research links to arm injury in young pitchers, because workload climbs right as the body is changing fastest.

Watch for

The mistake at 13 is treating a growth-driven jump in velocity as a green light to add volume. The arm did not get more durable just because it got faster. If anything, a bigger, stronger kid throwing harder needs the workload guardrails more, not less.

The curveball question at 13

Thirteen is the age the breaking-ball debate gets real. The honest answer is that overuse matters more than pitch type, but a young pitcher who has not mastered the fastball and changeup, and who lacks the control and maturity to throw a breaking ball well, is the one to worry about. We break down the evidence in [curveballs, velocity, and weighted balls](/library/curveballs-velocity-weighted-balls).

What matters more than the number

At 13, ride the natural velocity gains and protect the arm that is producing them. Stay inside [age-based pitch counts](/library/youth-pitch-counts-by-age), watch for [arm fatigue](/library/pitching-tired-arm-fatigue), and build velocity through the body rather than through max-effort shortcuts. The kids who stay healthy through this stretch are the ones still throwing hard at 17.

Education, not a medical diagnosis or treatment plan. If your pitcher has pain, consult a qualified sports-medicine professional.