What Size Hail Will Crack a Windshield?

Hail starts cracking car windows at about 2 inches across, the size of a lime or a hen's egg, and at baseball size (2 3/4 inches) it can shatter a windshield or punch a crater into it. Golf ball hail (1 3/4 inches) dents the hood and roof well before it breaks a windshield, which is why both "golf balls will break it" and "it takes baseballs" get repeated after every storm. The size is only half the answer: driving into the storm, strong wind, and glass with a painted edge all move the line down.

Golf balls or baseballs: why both answers are going around

The two answers come from two kinds of damage. Body panels are thin sheet metal, and the Northern Hail Project's Simon Eng puts visible dents at walnut size, around 30 to 35 mm (1 1/4 to 1 3/8 inches). Glass needs much more. "You would need some larger hailstones, usually 50 mm in diameter or larger," Eng told The Weather Network. "That's when you start to see cracking in windows on vehicles." At about 70 mm, baseball size, "windshields can be shattered" and the hail starts to put "big holes or craters" into them.

So the driver whose car came out of a golf ball storm with a dented roof and an intact windshield is right, and so is the one whose windshield broke in the same storm. The second car was usually moving, caught wind-driven hail, or took the hit on a weak spot.

What each hail size carries when it lands

Damage follows the energy a stone delivers, and energy grows with mass and with the square of speed. The National Severe Storms Laboratory (NSSL) gives fall speeds by size: 9 to 25 mph under 1 inch, 25 to 40 mph from 1 to 1 3/4 inches, and 44 to 72 mph from 2 to 4 inches, with stones over 4 inches able to pass 100 mph. Combine those speeds with the mass of a solid ice sphere (bubble-free ice is about 0.917 g per cubic centimeter, per the Journal of Glaciology) and you get the table below. Sizes are the National Weather Service names; the severe line is NSSL's.

The step between golf ball and lime is the whole story. Going from 1 3/4 to 2 inches adds only a quarter inch, but the stone gets half again as heavy and NSSL puts it in a faster fall band, so the energy jumps from at most 6.7 joules to between 12 and 33. That step is exactly where Eng's 50 mm cracking threshold sits.

Treat the energy column as a ceiling, not a measurement. NCAR and IBHS researchers who weighed and measured 2,295 Great Plains hailstones found that real hail, being lumpy rather than round, carries on average less fall speed and energy than a sphere of the same maximum diameter, "but can be larger."

What a windshield is built to take

The federal glazing standard, FMVSS 205, adopts ANSI/SAE Z26.1-1996, and its Test 12 drops a 227 g (half pound) smooth steel ball onto laminated glass from 30 feet (9.14 m). That ball lands at about 30 mph with about 20 joules, between a 2 inch hailstone at the slow end of its fall band (12 J) and the fast end (33 J). How the rest of the standard works is in FMVSS 205 in plain English.

The test does not ask the glass to stay uncracked. It passes if "the ball does not pass through the test piece," the laminate does not "break into separate pieces," and less than 645 mm² (about one square inch) of interlayer is exposed opposite the impact. In other words, it certifies that the PVB interlayer holds the broken glass and keeps the object out. A windshield that cracks under 2 inch hail is behaving the way the standard expects.

NHTSA's February 2026 research report (DOT HS 813 753) pushed production windshields past the standard height to find where they failed that exposed-interlayer limit. The results show where a windshield is weakest:

• Center of the glass. Production windshields failed between 40 and 60 feet, roughly 27 to 41 joules.
• Edge with the black paint. The same windshields failed between 20 and 35 feet, roughly 14 to 24 joules, while the unpainted edge held to 40 to 80 feet. "Overall, the unpainted glass was stronger than the painted," the authors wrote. That painted band is the ceramic frit around the glass, and it is one more reason cracks near the edge are treated differently.
• Temperature. Cold glass "withstood higher impacts than ambient," and ambient matched or beat hot glass. But when cold glass did fail, the ball went through instead of only exposing the interlayer.

Driving, wind and angle: what moves the threshold down

The table assumes a parked car and hail falling straight down. Three things change that.

• Driving into it. At 60 mph through hail falling at 40 mph, the stones meet the car at about 72 mph, which is more than three times the energy, and they arrive more head on. A windshield leans back, so a stone falling straight down on a parked car tends to strike it at a glancing angle; forward speed turns that into a direct hit. Slowing down or stopping is the single biggest change you control.
• Wind-driven hail. NSSL notes that with strong surface winds, hail "can fall at an angle or even nearly sideways" and can "break side windows on cars." The TORRO hailstorm scale makes the same point: walnut-sized hail in calm air "would not break vertical glass," but with strong winds the same hail "may smash many windows in a house and dent the bodywork of a car."
• Existing damage. A chip or short crack is a weak point already, and hail is a sharp load added to it. If your windshield had an unrepaired chip before the storm, check it first; what makes a crack spread explains why a minor strike can run it.

Sunroofs, rear and side glass are a different case

Most side, rear and roof glass is tempered glass (some cars use laminated side windows), and tempered glass does not crack and hold. Once it breaks, the whole pane goes. Z26.1 Test 6 for tempered glass uses the same 227 g ball from only 10 feet, about 7 joules, which is about what golf ball hail falling at 40 mph carries. In NHTSA's 2026 tests, rear quarter and sunroof glass struck at the edge of the painted area "broke while all unpainted tests did not result in fracture." The authors note the trend toward larger panoramic roofs means more painted area.

A glass roof also faces falling hail head on, where a raked windshield takes it at an angle. So on a car with a panoramic roof, the roof glass can be the first pane lost in a golf ball storm while the windshield survives. If it breaks, cover the opening before the next rain (see covering a broken car window), then read sunroof glass replacement and what roof glass costs.

After the storm: checking the glass and deciding repair or replace

Hail damage on a windshield is often a scatter of small bullseyes and star breaks rather than one obvious crack, and an adjuster counting dents can miss them. Check in this order:

1. Look from inside at a low angle. Sit in the driver's seat with the sun or a flashlight low across the glass. Fresh impacts catch the light as bright rings or short legs. Bullseye or star matters for repair.
2. Run a fingernail over each mark from outside. A mark you can catch is a break in the glass. A smooth spot that wipes away is not damage.
3. Measure each break and its distance to the edge. Use how a technician measures a chip or crack. Note anything near the black border, where the 2026 NHTSA tests found the glass weakest.
4. Count them. Several small chips are often still repairable, within limits covered in how many chips one windshield can take. A crack running from any impact, or breaks in the driver's line of sight, usually means replacement. Whether your windshield can be repaired has the full rules, and the repair or replace checker applies them to your break.
5. Check the roof, rear window and mirrors. Photograph everything with a coin for scale.

Hail is a comprehensive loss. Whether to put the windshield on the same claim as the dents, or file it on its own, depends on how your policy treats glass, and hail damage and glass claims walks through that choice. Some states require glass to be covered with no deductible, listed in zero deductible glass by state. Paying cash means roughly $300 to $500 for a replacement without a camera and $450 to $900 with one before calibration (see replacement cost line by line), and a camera car needs calibration after the new glass goes in.

Where these numbers stop applying

The thresholds are typical, not guarantees. Eng's 50 mm and 70 mm figures are field observations, not a lab rating for any windshield. The energy column assumes solid ice spheres, and real stones vary in shape, density and strength: in one season IBHS field teams weighed and crushed nearly 10,000 hailstones to map how size and strength vary across a storm. NHTSA's break heights come from one windshield type, a steel ball, and a failure defined by exposed interlayer, not by the first crack. Nothing here rates a particular windshield model.

What to do next

If hail of an inch or more is forecast, get the car under a roof: a garage or parking structure, and if you are caught driving in it, slow down. After the storm, inspect the glass from inside before you call anyone, and photograph every mark. Then start with how to file a glass claim, or go straight to the damage section to identify each break.

Frequently asked questions

Can golf ball size hail break a windshield?

It can, but usually it does not on a parked car. Golf ball hail is 1 3/4 inches, and researchers with the Northern Hail Project put the start of vehicle window cracking at about 2 inches. What makes golf balls break windshields is extra speed: driving into the storm, strong wind pushing the hail sideways, or a stone landing on an existing chip or on the painted edge of the glass, which NHTSA testing found to be the weakest area.

How fast does hail fall?

According to the National Severe Storms Laboratory, hail under 1 inch falls at about 9 to 25 mph, hail of 1 to 1 3/4 inches at 25 to 40 mph, and 2 to 4 inch hail at 44 to 72 mph. Stones over 4 inches can pass 100 mph. Real hailstones are lumpy and fall somewhat slower than perfect ice spheres, and wind can add a sideways component that matters a lot for side windows.

Is it safer to keep driving or stop in a hailstorm?

For the glass, slowing down helps most, because your forward speed adds to the speed of the hail and turns glancing blows on a raked windshield into direct hits. At 60 mph into hail falling at 40 mph, the stones strike at about 72 mph with more than three times the energy. Pull off where it is legal and safe, ideally under a roof, rather than stopping in a traffic lane.

Will insurance pay for a windshield broken by hail?

Yes, if you carry comprehensive coverage, which is the part of an auto policy that covers hail, falling objects and road debris. Liability only policies do not pay for your own glass. Your deductible applies unless your state or a glass endorsement waives it, and if the same storm dented the car you will usually want one claim covering both, which carries one deductible.

Can hail chips on a windshield be repaired?

Often, yes. Hail usually leaves small bullseye or star breaks, and each one is judged like any rock chip: its size, its distance from the edge, whether it sits in the driver's line of sight, and how many there are in total. Several small chips can usually be filled in one visit. Any break that has already grown a crack, or damage spread across the driver's view, normally means a new windshield.