What size hail damages a roof is the first question most Plano homeowners ask after a storm. The honest answer is that there is no single number. Size matters, but so do the roof’s age, its material, how many smaller storms it has already taken, and how hard the wind was blowing.
This guide sets out what federal weather scientists and roofing researchers have actually measured. It covers how hail is sized, the thresholds testing points to for asphalt shingles, how other roof types compare, and how big hail has been in the Plano area. It also explains how to judge your own roof without climbing on it.
What size hail damages a roof?
Hail of 1 inch, about the size of a quarter, is the size weather services call severe. Testing suggests most new asphalt shingles withstand the impact energy of typical 1.5-inch hail, while 2-inch hail separates stronger products from weaker ones. Older or weathered roofs can be damaged by smaller stones than new ones.
Three findings frame the answer:
- 1 inch is the severe threshold. NOAA’s National Severe Storms Laboratory (NSSL) hail guide states that hail quarter size or larger is considered severe. A quarter is 1 inch across.
- 1.5 inches is roughly what new shingles are built to survive. IBHS reported in its Front Range hail study that its testing has shown most asphalt shingle products, in their new state, should withstand the typical kinetic energies associated with 1.5-inch hail.
- 2 inches is the test that sorts products. The Insurance Institute for Business & Home Safety (IBHS) tests shingles with both 1.5-inch and 2.0-inch laboratory hailstones. Its aging research identified asphalt shingle products that perform well against 2-inch, realistic laboratory-made hailstones.
| Hail size | Common comparison (NSSL) | What it means for an asphalt shingle roof |
|---|---|---|
| Under 1 inch | Pea to nickel | Below the severe threshold, but repeated storms can wear a roof down |
| 1 inch | Quarter | Severe by the weather-service definition |
| 1.5 inches | Ping-pong ball | Most new asphalt shingles should withstand typical impacts, per IBHS |
| 1.75 inches | Golf ball | Larger than the 1.5-inch level IBHS cites for new shingles |
| 2 inches and up | Between golf ball and tennis ball | The size IBHS uses to separate stronger products from weaker ones |
How is hail measured and named?
Hail is measured across its widest point, in inches. Weather services compare stones with familiar objects so people can report size quickly, from a pea at a quarter inch to a grapefruit at four and a half inches. A ruler or tape measure gives the most reliable reading, which is why measured reports carry the most weight.
The NSSL hail guide lists the standard comparisons. A penny is 3/4 inch, a quarter 1 inch, a golf ball 1 3/4 inches, a tennis ball 2 1/2 inches, a baseball 2 3/4 inches and a softball 4 inches.
NSSL notes that comparing hail with an object of known size is good, but measuring with a ruler, calipers or tape measure is best. If you see hail at home, measuring a few of the largest stones and photographing them next to a ruler gives you a useful record. Do it only once the storm has passed and it is safe to go outside.
What size hail damages asphalt shingles?
For new asphalt shingles, damage becomes more likely above about 1.5 inches, and 2-inch hail is a test level where results differ between products. Impact-resistant shingles that rate well in IBHS testing hold up better at that size. Age and weathering lower the threshold for every product.
Asphalt is the roof most Plano homes have to worry about. IBHS’s synthetic shingle research page notes that asphalt shingles are used on about 80 percent of installed residential roofs in the United States.
IBHS assesses hail damage to shingles in its ratings programme as granule loss, dents, surface cracks, and at worst a fully compromised shingle. It buys the shingles from retail stores, because products sold as impact-resistant do not all perform the same.
Damage to a shingle also matters more than it looks. In its water leakage study, IBHS found a clear relationship between the size of a dent and the water leakage rate. Small dents let in negligible water. Large dents let in a great deal.
Can small hail under 1 inch damage a roof?
A single storm of small hail rarely breaks a sound shingle, but repeated small hail does add up. IBHS research found that frequent sub-severe hail knocks granules off asphalt shingles and speeds their aging. Roofs exposed to weathering and small-hail events became far more vulnerable to the next large storm.
IBHS calls hail under 1 inch “sub-severe”. Its small hail study reported three findings that matter to a homeowner:
- Cumulative damage. Repeated exposure to small hail can significantly reduce a roof’s resistance to later large hail.
- Accelerated aging. Small hail knocks away protective granules, exposing the asphalt underneath to sunlight and weathering.
- Higher vulnerability. Roofs exposed to natural weathering and two simulated small-hail events became up to ten times more susceptible to damage from later large hail than new shingles.
How do metal, tile and other roof types compare?
Each roof type is tested and judged differently. For asphalt shingles, IBHS assesses granule loss, dents, cracks and tears. For metal, dent thresholds are still being studied. Published, independent hail thresholds exist mainly for asphalt shingles, so for other materials the product’s own impact rating matters most.
IBHS advises that homeowners in areas with frequent hail can add protection through impact-resistant asphalt shingles rated Good or Excellent, or Class 4 rated metal, tile, or composite roofs. In its guide to identifying hail damage, IBHS notes that the shingles it rates have been tested to UL 2218 or FM 4473 standards for hail resistance.
Research on other materials is still developing. IBHS has tested synthetic composite shingles, which IBHS describes as potentially less prone to becoming brittle and having no granules to wear away. It has studied low-slope metal roofing, and its hail field study has been evaluating dent thresholds for stone-coated metal roofing.
| Roof type | How hail usually shows | What the public research says | What to ask for |
|---|---|---|---|
| Asphalt shingles (standard) | Granule loss, bruising, cracks, tears | Most new products withstand typical 1.5-inch impacts (IBHS) | Roof age and product name |
| Impact-resistant asphalt shingles | Same modes, at larger sizes | Performance varies by product; IBHS publishes ratings | The IBHS rating for the exact product |
| Metal | Dents | Dent thresholds for stone-coated metal under IBHS study | Class 4 rating; whether dents affect function |
| Concrete or clay tile | Not covered by the research we found | No independent public threshold found | Class 4 rating for the product |
| Synthetic composite | Not stated in the public summary | IBHS has tested three products; full results are members-only | Class 4 rating and any hail warranty terms |
We could not find a published, independent hail-size threshold for tile or metal roofs that we could link to. Treat any single “damage size” quoted for those materials with caution.
Why does the same hail damage one roof and not another?
Hail damage depends on impact energy, not just size, and on the roof that receives it. A stone’s density and fall speed, wind pushing it sideways, the roof’s age and weathering, and earlier storm damage all change the result. That is why one house can need a new roof while the house next door does not.
The factors that move the threshold:
- Roof age and weathering. IBHS found that natural short-term weathering can measurably reduce hail impact performance, and repeated hail exposure can accelerate that decline.
- Earlier small storms. As above, sub-severe hail can make a roof up to ten times more susceptible to later large hail.
- Air density. IBHS’s Front Range study gives an example: a 1-inch hailstone falling a mile above sea level has the same energy as a 1.2-inch hailstone in Dallas, because thinner air at altitude reduces drag.
- Wind. IBHS has deployed a wind-driven hail sensor to study hailstone impact angles. Wind changes which slopes take the hits.
- Where on the roof. The IBHS hail damage guide notes that ridge caps are especially vulnerable on an asphalt shingle roof.
How big has hail been in the Plano area?
Big enough to damage most roofs. Federal storm records show hail of 1 inch or larger in most reports across the Plano area over the past decade, and hail of 2 inches or more on 17 separate days. The largest reported stones were over 5 inches across. Every 2-inch day fell in spring or September.
The figures below come from the NOAA Storm Events Database, counted from the raw Storm Events data files for the Plano area from 2016 to 2025:
- 310 hail reports on 62 separate days.
- 265 of those reports were 1 inch or larger, the severe threshold.
- 63 reports of hail 2 inches or larger, on 17 days.
- The largest: 5.25 inches near Wylie on 11 April 2016, and 4.50 inches near Allen on 24 March 2019.
- Every day with hail of 2 inches or more fell between March and June, or in September.
Reports placed at Plano itself include hail of 1.75 inches on 23 March 2016; 1.75, 2.00 and 2.50 inches on 11 April 2016; 2.00 inches on 6 April 2018; and 3.00 inches on 20 April 2023. “Plano” in these records is a reference point used by the National Weather Service, not a test of city limits.
These are reports, not a full count of every hailstorm. Reports cluster where people live and can see the hail, and several reports can describe one storm. They still show that hail well above the 1.5-inch level reaches the area often.
How can you tell if hail was big enough to damage your roof?
Start with the evidence at ground level. Measured hail sizes, dents in gutters, downspouts, air-conditioning units and patio furniture, and granules or shingle pieces on the ground all suggest hail hit hard enough to matter. Confirming damage to the shingles themselves needs an inspection on the roof by a professional.
IBHS’s hail damage guide recommends checking collateral evidence first: spatter marks or impact dents on air-conditioning units, gutters, metal flashing, downspouts or patio furniture. Collateral damage confirms a hail event occurred.
The same guide lists look-alikes that are not hail damage:
- granule loss along the edges of shingles, which is normal weathering;
- uniform wear or discoloration;
- manufacturer defects;
- marks from installation, tools or foot traffic;
- granules knocked off by heavy rain.
Real hail damage on shingles shows a random pattern of impact marks, bruising that feels soft when pressed, and cracks or breaks where stones struck. Those checks happen on the roof, so leave them to someone with fall protection. Our guide to hail damage vs blistering vs normal wear explains the differences in more detail, with what to expect an inspector to show you.
What should you do after a storm with large hail?
Make sure everyone is safe, stay away from downed power lines and report them to the utility, and stay off the roof. Then document what you can see from the ground, read your insurance policy, and arrange a professional inspection with photographs and a written report of every finding.
A professional inspection should cover each roof slope, the ridge, flashing and vents, gutters and soft metal. It should end with a written report that separates hail damage from wear. Our guide to what a roof inspection after a hail storm should include lists what to expect and what to ask for.
Insurance is a separate question. Your policy and your insurer decide what is covered, and terms vary between insurers. IBHS’s guide suggests calling your insurance agent first to report suspected hail damage. Confirm deadlines and deductibles with your insurer before relying on any general advice.
If you want a professional to check your roof after a hailstorm, Roofing Repair Plano’s storm and hail damage roof repair service starts with an inspection and photographs, and a written explanation of what we find.
For the wider picture of repair against replacement, our complete roof damage repair-or-replace guide works through roof age, extent of damage and decking condition in order.
Frequently asked questions
Can quarter-size hail damage a roof?
It can, especially on an older or weathered roof. Quarter-size hail, 1 inch across, is the level weather services call severe. IBHS testing suggests most new asphalt shingles withstand typical 1.5-inch impacts, but aging and earlier small storms can lower the size that causes damage. An inspection settles it.
What size hail damages asphalt shingles?
There is no fixed number. IBHS reports that most new asphalt shingles should withstand typical impacts from 1.5-inch hail, and it tests products at 1.5 and 2 inches. Above about 1.5 inches damage becomes more likely, and weathered shingles can be damaged by smaller stones than new ones.
Does small hail damage a roof over time?
Yes. IBHS research found that repeated small hail, under 1 inch, knocks granules off asphalt shingles and speeds aging. Roofs exposed to weathering and two simulated small-hail events became up to ten times more susceptible to damage from later large hail than new shingles.
How big has hail been in the Plano area?
NOAA Storm Events records for the Plano area list 310 hail reports on 62 days from 2016 to 2025. Hail of 2 inches or larger was reported on 17 days, and the largest was 5.25 inches near Wylie on 11 April 2016. These are reports, not a count of every storm.
How do I know if hail damaged my roof?
Look for dents in gutters, downspouts, air-conditioning units and patio furniture, and granules or shingle pieces at downspout outlets. Those signs confirm hail fell hard enough to matter. Damage to the shingles themselves needs a professional inspection on the roof. Do not climb onto the roof yourself.
