City comparison
San Diego, CA is about 425 miles (700 km) from Union City, CA in a straight line. By road, the drive is roughly 550 miles, or about 9 h behind the wheel at highway speeds.
Driving distance is a rough estimate (great-circle × 1.25); driving time assumes a 60 mph blended average. Real trips run 10–20% longer with stops.
A direct flight from San Diego, CA to Union City, CA takes about 52 min, covering roughly 425 miles in a straight line. Connecting itineraries with a layover typically add 1–3 hours.
Block-to-block estimate at ~500 mph cruise, including taxi, climb, and descent — what an airline would publish, not pure airborne time.
San Diego has a population of 1,383,987, vs 69,502 in Union City — about 19.9× larger by population. By land area, San Diego covers about 325 sq mi vs 19 sq mi for Union City.
Population from US Census ACS. Land area from the Census Gazetteer (city proper, excluding inland water).
Cost indices by category, with the US city average (100) marked.
Index: 100 = US city average. Lower is more affordable.
Side-by-side costs, salaries, and sub-category indices.
| Metric | San Diego | Union City | Difference |
|---|---|---|---|
| Median rent | $2,080/mo | $2,593/mo | 24.7% higher in Union City |
| Median home value | $783,300 | $1,006,600 | 28.5% higher in Union City |
| Median household income | $98,657 | $138,013 | 39.9% higher in Union City |
| Groceries index | 107.6 | 108.1 | ≈ equal (Union City slightly higher) |
| Utilities index | 169.8 | 168.3 | 0.9% higher in San Diego |
| Transportation index | 100.0 | 106.1 | 6.0% higher in Union City |
| Healthcare index | 100.0 | 106.0 | 6.0% higher in Union City |
How much you'd need to earn in the other city to keep the same standard of living.
If you earn $100,000 in San Diego, you'd need $106,662 in Union City to maintain your standard of living.
Climate, safety, and demographics side by side.
San Diego, CA is about 6.2% cheaper overall than Union City, CA, based on our cost-of-living index. Housing costs are roughly 10% higher in Union City than in San Diego. If you earn $80,000 in San Diego, you'd need about $85,330 in Union City to keep the same standard of living.