Radon testing is one of the cheapest and most impactful things you can do for your family's health. But walk into any hardware store or search online and you'll face an immediate question: should you grab a $15 DIY kit, or should you spend $150+ on a certified professional?
The honest answer is: it depends on your situation. Both methods detect radon. Both can give you useful information. But they differ significantly in accuracy, detail, legal standing, and convenience. This guide breaks down everything you need to know so you can make the right choice for your home, your budget, and your circumstances.
Quick Comparison: DIY vs Professional
| Feature | DIY Test Kit | Professional Test |
|---|---|---|
| Cost | $10 – $50 | $125 – $400 |
| Testing method | Passive (charcoal or alpha track) | Active (continuous radon monitor) |
| Data collected | Single average number | Hourly readings for 48+ hours |
| Accuracy | ± 25% (when done correctly) | ± 10% (calibrated equipment) |
| Time to results | 7 – 14 days (mail to lab) | Same day or next day |
| Tamper detection | None | Built-in (motion, barometric) |
| Real estate accepted | Generally no | Yes — certified report |
| Placement guidance | Included instructions | Professional selects optimal location |
| Effort required | You place kit, mail it, wait | Pro handles everything |
DIY Radon Test Kits: What You Need to Know
DIY radon test kits are passive devices that absorb radon gas over a set period, then get mailed to a certified laboratory for analysis. They're the most affordable way to test and are perfectly adequate for routine screening. There are two main types:
Charcoal Canister Kits ($10–$20)
The most common type. An activated charcoal canister is exposed to the air in your home for 2 to 7 days. Radon gas adsorbs onto the charcoal surface, and the lab measures the captured radioactivity to calculate the average radon concentration during the exposure period.
Charcoal kits are cheap and widely available, but they have limitations. They're sensitive to humidity (high moisture can reduce charcoal's ability to absorb radon), and they can't be deployed for more than 7 days because the radon that was absorbed starts to decay and escape. They give you a snapshot of a short window, not a long-term average.
Alpha Track Detectors ($15–$50)
Alpha track detectors use a small piece of plastic or film that records microscopic damage tracks when struck by alpha particles from radon decay. They can be deployed for both short-term (2–7 days) and long-term testing (90 days to 1 year), and they're less affected by temperature and humidity than charcoal kits.
For long-term testing, alpha track detectors are the gold standard among passive devices. A 90-day to 1-year alpha track test gives you the most accurate picture of your average annual radon exposure — the number that actually determines your health risk.
💡 Tips for Accurate DIY Testing
- • Place the kit in the lowest livable level of your home (basement if you use it, otherwise first floor)
- • Keep it at least 20 inches above the floor and away from exterior walls, windows, and humidity sources
- • Maintain closed-house conditions during testing: keep windows and doors closed (normal entry/exit is fine)
- • Don't place near drafts, vents, fireplaces, or high-humidity areas like bathrooms
- • Don't move the kit once placed
- • Mail it to the lab promptly after the testing period ends
- • Consider running two kits side by side — if results agree within 25%, you can be more confident in the reading
Professional Radon Testing: What You Get
Professional radon testing uses continuous radon monitors (CRMs) — sophisticated electronic devices that measure radon levels every hour and record the data digitally. A certified radon measurement professional deploys the monitor in your home, retrieves it after a minimum of 48 hours, and provides a detailed report.
What Makes Professional Testing Different
Hourly data logging
Instead of one average number, you get radon readings for every hour of the test. This reveals patterns — radon often spikes at night when the house is closed up and HVAC isn't running. Your professional can interpret these patterns and identify potential issues.
Tamper detection
CRMs include motion sensors, barometric pressure sensors, and other tamper-detection features. If someone moves the device, opens a window, or otherwise disrupts closed-house conditions, it's recorded in the data. This is critical for real estate transactions where results have legal and financial implications.
Calibrated accuracy
Professional CRMs are calibrated annually against known radon sources and typically achieve ±10% accuracy. DIY kits, even when used correctly, have a wider tolerance (±25% or more).
Certified reporting
The results come in a formal report from a certified professional, meeting the standards required by lenders, real estate agents, and home inspectors. The report includes the tester's credentials, device calibration records, and detailed methodology.
Expert interpretation
A professional doesn't just hand you a number — they explain what it means, whether it's borderline or clearly elevated, what factors might be influencing it, and what your next steps should be.
When to Choose DIY Testing
DIY kits are the right choice in several common scenarios:
- First-time screening: You've never tested your home and want to know where you stand. A $15 charcoal kit gives you a useful first data point.
- Routine re-testing: The EPA recommends testing every 2 years. If you tested professionally before and want a periodic check, a DIY kit is cost-effective.
- Post-renovation check: You remodeled your basement or added an addition and want to verify radon levels haven't changed.
- Long-term baseline: A 90-day alpha track test gives you the most accurate annual average — better than any short-term test, DIY or professional.
- Budget-conscious screening: If $125+ is a barrier, a $15 kit is infinitely better than no test at all.
When to Choose Professional Testing
Professional testing is the better (or necessary) choice in these situations:
- Buying or selling a home: Most lenders, real estate agents, and buyers require a certified professional test. DIY kits aren't accepted in real estate transactions.
- Confirming a high DIY result: If your DIY kit came back elevated (at or above 4 pCi/L), a professional test provides confirmation before you commit to mitigation ($800–$2,500).
- You need fast results: Professional tests give results in 48 hours. DIY kits take 1–2 weeks after mailing to the lab.
- You want detailed data: Hourly readings reveal patterns that a single average number can't. This helps diagnose the source of radon entry and plan mitigation.
- Legal or insurance purposes: If you need documented, defensible radon results for any legal, insurance, or dispute resolution purpose.
The Smart Two-Step Approach
Many radon professionals and the EPA itself suggest a two-step approach that uses both methods strategically:
Screen with a DIY kit first
Buy a short-term charcoal kit ($10–$20) and test your lowest livable level. If it comes back below 2 pCi/L, you're in good shape — retest in 2 years. If it's between 2–4, consider a long-term alpha track test for a more accurate reading.
Confirm with professional testing if elevated
If your DIY test comes back at 4 pCi/L or above, hire a certified professional for a 48-hour CRM test. This confirms the result with greater accuracy and gives you a detailed, certified report you can use to get mitigation quotes.
This approach costs $25–$70 total if your initial screening is low (and you're done). If it's elevated, you spend an additional $125–$275 for professional confirmation — but you're getting it only when it matters, saving money when it doesn't.
The Third Option: Personal Continuous Monitors
If you want ongoing peace of mind, consider purchasing a personal continuous radon monitor like the Airthings Wave ($150–$200) or Ecosense RadonEye ($150–$200). These devices plug in or run on batteries and continuously measure radon levels, displaying real-time data on the device or a smartphone app.
They're not as accurate as professional CRM equipment and aren't accepted for real estate transactions, but they're excellent for ongoing monitoring — especially if you have a mitigation system and want to verify it's still working. Over time, the one-time purchase cost is cheaper than repeated professional tests.
✅ Bottom Line
Any test is better than no test. If budget is a concern, grab a $15 DIY kit today. If you're buying or selling a home, hire a certified professional. If you want the most accurate long-term picture, deploy a 90-day alpha track detector. The worst choice is the one most people make: not testing at all.