DIY test kit
$15-$40
Low-cost screening for homeowners.
California Radon Testing Cost
Testing costs are usually consistent across states. Your final price depends more on test type, timeline, and whether you use a pro.
Testing cost ranges
Short-term professional test
$150-$250
Useful for fast decisions.
Long-term professional test
$200-$400
Best for understanding seasonal average exposure.
Continuous radon monitor
$300-$800
Tracks trends over time with repeat readings.
When to test
- Test every home at least once, even if neighbors had low results.
- Retest after major renovations, HVAC changes, or adding living space below grade.
- Use colder-season testing windows when possible for more conservative readings.
- Test again after any mitigation installation to confirm performance.
Types of radon tests
- DIY short-term kits: Good for quick screening and budgeting decisions.
- Professional short-term tests: Better when you need documentation for real-estate timelines.
- Long-term tests: Better picture of year-round average radon levels.
- Continuous monitors: Helpful for tracking trends and post-mitigation confidence.
What results mean
EPA recommends taking action when results are at or above 4.0 pCi/L. Homes below that number should still be retested over time, because radon levels can change by season and weather.
FAQ
How much does radon testing cost in California?
DIY kits usually run $15-$40, professional short-term tests are often $150-$250, and long-term professional testing is commonly $200-$400.
When should I test my home for radon?
Test during colder months when windows stay closed, then retest after major renovations or after installing mitigation.
Should I choose DIY or professional testing?
DIY is affordable for screening, while professional testing is better when you need documentation for a sale or negotiation.
What do radon test results mean?
EPA recommends action at 4.0 pCi/L or higher. Results below that still benefit from periodic retesting over time.