Hail about 1 inch in diameter (quarter size) is the point where most asphalt shingle roofs start to take functional damage. That 1 inch mark is also the National Weather Service threshold for a “severe” thunderstorm. Softer or aging materials can bruise at 0.75 to 1 inch, while metal panels dent cosmetically at even smaller sizes. What size hail can damage a roof depends on the material, its age, wind speed, and roof slope, so the honest answer is a range, not a single number.
What size hail damages a roof: the short answer
For a standard asphalt shingle roof, the practical damage threshold is roughly 1 inch to 1.25 inches in diameter, the size of a quarter to a half dollar. Below 1 inch, most shingles shrug off the impact unless they are old, brittle, or hit repeatedly with wind driving the stones sideways. At 1.5 inches (ping pong ball) and up, widespread bruising and granule loss become common across the whole slope.
The 1 inch figure lines up with weather science. The National Weather Service classifies any thunderstorm producing hail 1 inch or larger as severe, because that is the size where damage to property becomes likely. Roofing material thresholds and the storm-warning threshold converge at almost the same number, which is why 1 inch is the number adjusters and inspectors reach for first.
Hail size chart: NOAA object comparisons and diameters
Field spotters and insurers describe hail by comparing it to everyday objects, using the official Storm Prediction Center (SPC) conversion. Knowing the diameter behind each object tells you whether a storm crossed your roof’s damage threshold. Use this chart to translate what you saw, or what a report listed, into a real measurement.
| Diameter | Common object (NOAA/SPC) | Roof risk |
|---|---|---|
| 0.50 in | Marble, mothball | Rarely damages shingles; can mark aging or soft metal |
| 0.75 in | Penny | Low risk; brittle or old roofs may bruise |
| 0.88 in | Nickel | Borderline; wind-driven stones can start granule loss |
| 1.00 in | Quarter | Severe threshold. Asphalt damage becomes likely |
| 1.25 in | Half dollar | Functional bruising common on most shingles |
| 1.50 in | Walnut, ping pong ball | Widespread damage; wood shakes and tile at risk |
| 1.75 in | Golf ball | Heavy bruising, cracked tiles, dented metal |
| 2.00 in | Hen egg | Severe roof and exterior damage almost certain |
| 2.50 in + | Tennis ball and up | Punctures, splits, and structural risk |
Diameters come from the SPC hail size conversion table. A “quarter” is not a loose guess; it means a stone at or above 1.00 inch, which is why spotters and storm reports use these object names.
Hail damage threshold by roofing material
Different materials fail at different hail sizes because impact resistance varies by thickness, flexibility, and age. The table below gives the approximate diameter at which each common roofing material begins to sustain damage. Softer and older products sit at the low end; thick, impact-rated products sit higher.
| Roofing material | Damage begins around | What the damage looks like |
|---|---|---|
| Aging or brittle 3-tab asphalt | 0.75 to 1.0 in | Granule loss, soft bruises, exposed mat |
| Standard 3-tab / architectural asphalt | 1.0 to 1.25 in | Round bruises, cracked mat, granule loss |
| Fiber cement and flat concrete tile | ~1.25 in | Surface chips, hairline cracks |
| Wood shakes and thick fiberglass shingles | ~1.5 in | Splits along the grain, deep dents |
| Clay and heavy concrete tile | 1.5 to 1.75 in | Cracks, spalling, shattered tiles |
| Metal panels (steel, aluminum) | 0.75 to 1.0 in (cosmetic) | Dents; often cosmetic before functional |
| Impact-rated (Class 4) shingles | 1.75 in and up | Designed to resist a 2 in steel ball in UL 2218 testing |
Two points get lost in most guides. First, metal dents at smaller sizes than asphalt functionally fails, but a dent may be cosmetic rather than a leak risk, which changes how a claim is handled. Second, Class 4 impact-rated shingles pass the UL 2218 test by surviving a 2 inch steel ball dropped from about 20 feet, so they buy real headroom in hail country. For how a bruised shingle actually presents on the roof, see our guide on hail damage to roof shingles.
Why 1 inch hail can damage a roof
A 1 inch hailstone damages a roof because of the energy it carries at impact, not just its width. Terminal velocity rises with size, so bigger stones hit harder even before wind is factored in. A quarter-size stone falling at 25 to 40 mph delivers enough force to fracture the asphalt mat under the granules, which is the bruise an inspector presses for.
Per NWS figures, hail in the 1 to 1.75 inch range typically falls between 25 and 40 mph. A golf ball-size stone (1.75 in) reaches roughly 70 mph, and a baseball-size stone (2.75 in) approaches 90 mph. Doubling the diameter far more than doubles the impact energy, which is why the jump from 1 inch to 1.75 inch turns scattered bruises into a full replacement conversation.
What else decides whether hail damages your roof
Size sets the baseline, but four other factors move the threshold up or down on a given storm. A 1 inch storm can total an old roof and barely mark a new one next door. These are the variables an inspector weighs alongside stone size.
- Roof age and material condition. Weathered shingles that have already shed granules bruise at smaller sizes because the mat is closer to the surface.
- Wind speed and direction. Wind drives stones at an angle, raising impact force and concentrating hits on windward slopes.
- Roof slope. Steeper pitches deflect glancing blows; low-slope and flat sections take more direct hits.
- Storm duration and density. A short burst of 1 inch hail does less than a sustained fall that strikes the same shingle repeatedly.
Because these variables stack, two roofs on the same street can end up with different verdicts. That is why the number of impacts per test square, not just the reported hail size, drives the replace-or-repair call. Our breakdown of how much hail damage it takes to replace a roof walks through the adjuster standards.
Hail size and metal versus asphalt roofs
Metal roofs dent at smaller hail sizes than asphalt roofs functionally fail, but denting and failure are not the same thing. A steel or aluminum panel can show cosmetic dents from sub-1 inch hail while still shedding water perfectly. Asphalt, by contrast, reaches functional damage where metal reaches cosmetic damage, at close but different points on the size scale.
This distinction matters for claims. Some insurers treat metal denting as cosmetic and may exclude it, while others cover it. For the specifics on denting, coverage, and the cosmetic-versus-functional line, see metal roof hail damage. To understand how any hail claim is filed and paid, our guide to the hail damage roof insurance claim process covers the timeline and documentation.
Verify the hail size that hit your address
You do not have to guess what size hail fell on your roof. Ground reports, radar-derived hail size, and insurer storm data can confirm the diameter for a specific date and location. Matching that measurement against the material thresholds above tells you whether an inspection is worth booking.
Our 2026 roofing hail and storm loss database compiles state-by-state hail and storm loss history so you can check how often damaging hail hits your region. For the wider learning path on materials, inspections, and claims, start at the Learn About Roofing hub. If your storm cleared the 1 inch mark, a professional inspection is the next step, since surface bruising is not always visible from the ground.
Frequently asked questions
What is the smallest hail that can damage a roof?
Hail as small as 0.75 to 1 inch (penny to quarter size) can damage a roof, but usually only when shingles are old, brittle, or already worn. Metal panels can dent cosmetically below 1 inch. On a newer asphalt roof, meaningful functional damage typically starts around the 1 inch mark, which is also the National Weather Service severe-storm threshold.
Can 1 inch hail damage a roof?
Yes, 1 inch hail (quarter size) can damage most asphalt shingle roofs. One inch is the National Weather Service threshold for a severe thunderstorm precisely because damage becomes likely at that size. Whether your specific roof is affected also depends on shingle age, wind speed, roof slope, and how long the hail fell.
How big does hail need to be to damage shingles?
Standard asphalt shingles generally begin taking functional damage at about 1 to 1.25 inches in diameter, roughly quarter to half dollar size. Aging or brittle shingles can bruise closer to 0.75 inch, while impact-rated Class 4 shingles are built to resist a 2 inch steel ball in UL 2218 testing and often survive larger hail.
Does hail size damage metal roofs differently than asphalt?
Yes. Metal roofs tend to dent cosmetically at smaller hail sizes than asphalt roofs reach functional failure, but a dent may not create a leak. Asphalt fails when the mat fractures under the granules. Because metal denting can be cosmetic, insurers vary in whether they cover it, which affects how a claim is handled.
Is 2 inch hail enough to replace a roof?
Two inch hail (hen egg size) almost always causes severe roof damage and frequently leads to full replacement. At that diameter, stones fall fast enough to fracture mats, crack tiles, and dent metal across the whole slope. The final replace-or-repair decision still depends on impact density per test square, which an adjuster measures during inspection.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.