Diamond Bar, CA vs San Mateo, CA: Crime Rate Comparison (2025)
A side-by-side look at reported crime in Diamond Bar and San Mateo, on the FBI-based Crime Index (0–100, higher = safer) for 2025.
San Mateo is the safer city
San Mateo scores 81/100 (grade B) versus 80/100 (grade B) for Diamond Bar — a 1-point gap. Diamond Bar's violent-crime rate is -26% vs San Mateo. Across the 8 offense categories, San Mateo has the lower rate in 2.
Diamond Bar, CA
Crime Index
- Population
- 51,635
- Violent / 100k
- 124
- Property / 100k
- 1,635
- In California
- #40 of 175
San Mateo, CA
SaferCrime Index
- Population
- 102,362
- Violent / 100k
- 167
- Property / 100k
- 1,501
- In California
- #39 of 175
Crime rates head-to-head
| Metric | Diamond Bar | San Mateo | US average |
|---|---|---|---|
| Crime Index (higher = safer) | 80B | 81B | 73C |
| Violent crime /100k | 124 | 167 | 315 |
| Property crime /100k | 1,635 | 1,501 | 1,487 |
| Homicide /100k | 0 | 0 | 4.1 |
| Total reported /100k | 1,759 | 1,668 | 1,802 |
Grade shown per index band (88–100 = A … 0–29 = F). Rates are reported offenses per 100,000 residents.
By offense
Rate per 100,000 residents — the lower (safer) city is highlighted.
| Offense | Diamond Bar | San Mateo |
|---|---|---|
| Homicide | 0 | 0 |
| Rape | 13.6 | 31.3 |
| Robbery | 40.7 | 38.1 |
| Aggravated assault | 69.7 | 97.7 |
| Burglary | 598 | 79.1 |
| Larceny-theft | 928 | 1,294 |
| Motor vehicle theft | 108 | 119 |
| Arson | 0 | 7.8 |
Crime trends
Diamond Bar
San Mateo
Frequently asked questions
Is Diamond Bar or San Mateo safer?
Which has more violent crime, Diamond Bar or San Mateo?
What are the odds of violent crime in Diamond Bar vs San Mateo?
No area has zero risk
A high Crime Index score means lower reported crime relative to other US cities — it is not a guarantee of safety. Reported crime is not the same as actual crime. Research on the gap between crime that occurs and crime that gets reported to police — often called the "dark figure" of crime — estimates that roughly 40% of violent crime and about a third of property crime go unreported each year. Every index built on official statistics, including this one, necessarily undercounts real crime. That gap is exactly why homicide — the offense with the smallest dark figure — anchors the calculation instead of a more commonly reported but less reliable category like theft.
Scores on this page reflect FBI-reported data for 2025. See the full methodology →
Protecting yourself in Diamond Bar & San Mateo
Worried about the numbers above? Compare local providers, estimate costs, and explore the right kind of coverage.