Hail around 1 to 1.5 inches across is where roof damage commonly starts. Below 1 inch, standard shingles usually shrug it off; from about 1.75 inches, golf ball size, most roofing materials are at risk. The chart below gives every size in inches with the object it is compared to.
What are the standard hail sizes?
Hail is measured across its widest point and reported with an everyday comparison, the scale weather spotters use when they send reports to the National Weather Service. RoofQuery storm reports print the same names next to every size.
| Diameter | Compared to | What it means for a roof |
|---|---|---|
| 0.75" | Penny | Below damage size for most roofing; a storm report's first listed size |
| 0.88" | Nickel | Rarely damages shingles |
| 1.00" | Quarter | Severe by NWS definition; can damage three-tab shingles |
| 1.25" | Half dollar | Can damage laminated shingles |
| 1.50" | Ping-pong ball | Commonly damages asphalt shingles |
| 1.75" | Golf ball | NWS "considerable" damage threat |
| 2.00" | Hen egg | Damages most roofing materials |
| 2.50" | Tennis ball | Widespread roof damage likely |
| 2.75" | Baseball | NWS "destructive" damage threat |
| 3.00" | Tea cup | Penetrates many roof coverings |
| 4.00" to 4.50" | Grapefruit, softball | Extreme; structural damage possible |
What size hail is called severe?
One inch. The National Weather Service treats a thunderstorm as severe when it produces hail of 1 inch or larger, winds of 58 mph or more, or a tornado. Its warnings also carry damage threat tags: "considerable" from 1.75-inch hail and "destructive" from 2.75-inch hail. A RoofQuery storm report lists the warnings that covered the property and the hail size each one called for.
What size hail damages shingles?
About 1 inch for standard three-tab asphalt shingles and 1.25 inches for heavier laminated shingles. Those are the thresholds found in impact tests presented to the American Meteorological Society, which fired ice spheres of increasing size at common roofing products until most impacts caused damage: a puncture, a tear or a bruise in the shingle mat. Stiffer and thicker materials such as tile, slate and metal need larger stones before they fail, and the threshold falls as a roof ages.
Why doesn't hail size alone prove damage?
Because the outcome depends on more than diameter. Wind drives stones in at an angle and harder; dense hail does more than slushy hail; an older, brittle roof fails sooner; and a roof facing the storm takes more hits than the far side. Hail also falls unevenly, so the largest stone in a neighbourhood may not have reached a given house. That is why a storm report gives the size at the property and within 1, 3 and 5 miles separately, and why its damage chance rating is a likelihood, not a finding. An inspection confirms damage.
How do storm reports use these sizes?
The hail table lists dates with 0.75-inch hail at or within 1 mile of the property, or 1-inch hail within 3 miles, with each size colour-coded and named. The damage chance rating is high when 1.5-inch hail reached the property or within a mile, and medium from 1 inch nearby or 1.5 inches within 3 miles. What's in a storm report covers the rest, and how radar hail estimates work explains where the sizes come from.
Frequently asked questions
What size hail damages a roof?
Damage commonly starts around 1 inch for standard three-tab shingles and 1.25 inches for laminated shingles, and becomes likely for most roofing from about 1.75 inches, golf ball size.
Is quarter-size hail severe?
Yes. The National Weather Service defines severe hail as 1 inch or larger, which is quarter size.
Can pea-size hail damage a roof?
Rarely on its own. Hail under 0.75 inches seldom damages roofing, though wind-driven hail can strip granules from old or worn shingles.