Air Filter Performance Calculator
Understanding Your Filter
Compare air filter performance using industry-standard CFM ratings at different pressure drops. Remember: CFM measures airflow volume while PSI measures pressure drop. You cannot convert between them.
Input Filter Specifications
Performance Results
Performance Rating
Important Note
Remember: CFM and PSI are not interchangeable. High CFM values with low pressure drop (like 0.5 PSI) indicate better airflow. Never trust claims like "120 PSI flow" - no filter is designed for 120 PSI pressure.
Filter Comparison
| Pressure Drop | CFM Value | Performance Level |
|---|
There’s a common misunderstanding out there: people think PSI and CFM are interchangeable when talking about air filters. They’re not. You can’t just swap one for the other like units on a ruler. If you’re asking, How many CFM is 120 PSI?, you’re mixing up two completely different measurements - and that’s going to lead you down the wrong path when choosing or upgrading your air filter.
What CFM Actually Means for Air Filters
CFM stands for Cubic Feet per Minute. It’s a measure of airflow. Think of it like how much air your engine can suck in every minute. A high-flow performance air filter might move 800 CFM, while a stock paper filter might only handle 400 CFM. The higher the CFM, the more air your engine gets - which means more oxygen to burn fuel, and potentially more power.
But CFM doesn’t tell you anything about pressure. It doesn’t care if the air is coming in at 10 PSI or 120 PSI. It just counts how much air passes through over time. That’s why you can’t convert CFM to PSI - they measure different things.
What PSI Actually Means in Air Filter Systems
PSI stands for Pounds per Square Inch. It’s a unit of pressure. In air filter applications, PSI usually refers to the pressure drop across the filter - not the pressure of the air entering the engine. A typical stock air filter might have a pressure drop of 1-2 PSI at peak airflow. A high-performance filter might drop just 0.5 PSI under the same conditions.
When someone says “120 PSI,” they’re usually thinking of compressed air systems - like air tools, paint sprayers, or tire inflators. Those systems use compressors to force air into tanks at high pressures. But your engine doesn’t work that way. It doesn’t need 120 PSI of air pressure. In fact, if your intake system was pushing 120 PSI into the engine, you’d be dealing with a turbocharger or supercharger, not a simple air filter.
Why 120 PSI Doesn’t Apply to Air Filters
Here’s the reality: your engine’s intake system operates at near-atmospheric pressure. At sea level, that’s about 14.7 PSI. Even with a turbocharger boosting your engine to 20 PSI of boost, the air filter itself isn’t seeing 120 PSI. That pressure is created downstream, inside the intake manifold - not at the filter.
There’s no performance air filter on the market designed to handle 120 PSI. If you tried to force that much pressure through a filter, it would rupture. The filter media isn’t built for that. It’s designed to let air flow freely while trapping dust and debris - not to act like a pressure vessel.
So when you hear someone say, “My filter flows 120 PSI,” they’re either misinformed or using the wrong terminology. They probably meant to say “120 CFM.” Or maybe they’re thinking of a compressor’s output, not an engine’s intake.
What You Should Be Measuring Instead
If you’re shopping for a performance air filter, ignore PSI entirely. Focus on these two things:
- CFM rating at a standard pressure drop - Reputable brands like K&N, AEM, or Injen will list CFM at 0.5 PSI or 1.0 PSI. That’s the industry standard. A filter rated at 850 CFM @ 0.5 PSI is better than one rated at 700 CFM @ 1.0 PSI - even if the numbers seem lower.
- Filter efficiency - How well does it trap dirt? High CFM means nothing if your engine is sucking in sand. Look for filters with 98%+ efficiency ratings.
Don’t trust claims like “120 PSI flow” or “120 CFM at 120 PSI.” Those are marketing nonsense. Real performance data is always tied to a pressure drop - not a pressure level.
Real-World Example: What Happens When You Get It Wrong
Last year, a customer in Adelaide bought a “high-pressure” air filter because the seller claimed it could handle “120 PSI.” He installed it on his turbocharged Subaru. Within a week, the filter collapsed under boost pressure. He didn’t realize that the filter wasn’t designed to withstand that kind of force - and that the real issue was airflow restriction, not pressure.
He ended up spending $300 on a new filter, $150 on a mechanic to fix the intake ducting, and another $200 on a dyno tune to recover lost power. All because someone confused pressure with flow.
That’s the danger of mixing up CFM and PSI. It’s not just misleading - it’s expensive.
How to Choose the Right Air Filter
Here’s what to look for when buying a performance air filter:
- Check the manufacturer’s CFM rating - and make sure it’s listed at 0.5 PSI or 1.0 PSI.
- Compare filters using the same pressure drop. Don’t compare a 750 CFM @ 1.0 PSI filter to a 900 CFM @ 2.0 PSI filter - the latter is actually worse.
- Look for third-party testing. Brands like SAE (Society of Automotive Engineers) or independent dyno shops often test filters under real conditions.
- Make sure the filter fits your vehicle’s housing. A filter that flows 1,000 CFM won’t help if it doesn’t seal properly.
- Consider the environment. If you drive on dusty roads, a filter with higher efficiency matters more than raw CFM.
Top performers in 2025 include the K&N 33-2318 (920 CFM @ 0.5 PSI), the AEM DryFlow (880 CFM @ 0.5 PSI), and the Injen SR Series (900 CFM @ 0.4 PSI). These are all tested and verified - no vague PSI claims in sight.
Final Answer: You Can’t Convert 120 PSI to CFM
There’s no answer to “How many CFM is 120 PSI?” because the question doesn’t make physical sense. You can’t convert pressure into airflow. They’re not the same thing. One measures volume over time. The other measures force per area.
If you’re trying to upgrade your air filter for more power, forget about PSI. Focus on CFM ratings at standard pressure drops, filter efficiency, and proper fitment. That’s how real performance gains are made - not by chasing misleading numbers.
And if someone tells you their filter flows at 120 PSI? Walk away. They don’t understand how engines work - and you don’t want to risk your engine to someone who doesn’t either.
Can a performance air filter handle 120 PSI of pressure?
No. Performance air filters are not designed to handle pressure above 5-10 PSI. They’re meant to allow air to flow freely with minimal resistance, not to contain high-pressure air. If you’re seeing 120 PSI in your intake system, you’re likely dealing with a turbocharger or supercharger - and even then, the air filter itself is only exposed to the pressure drop across it, not the full boost pressure.
What’s the difference between CFM and PSI in air filters?
CFM measures how much air flows through the filter per minute. PSI measures the pressure drop - or resistance - the filter creates as air passes through. High CFM means more airflow. Low PSI drop means less restriction. You want high CFM and low PSI drop for better performance. They’re not interchangeable.
Why do some sellers say their filter flows at 120 PSI?
That’s either a mistake or a scam. No air filter flows at 120 PSI - that’s the pressure of a heavy-duty air compressor, not an engine intake. It’s likely they meant 120 CFM and confused the units. Always check the manufacturer’s official specs. If they don’t list CFM at a standard pressure drop, avoid the product.
Does higher PSI mean more power?
No. Higher pressure drop (PSI) across the filter means the engine has to work harder to pull air in - which reduces power. Lower pressure drop means easier airflow, which helps the engine breathe better. That’s why performance filters aim for low PSI drop - not high.
What’s a good CFM rating for a performance air filter?
It depends on your engine size and modifications. For a naturally aspirated 2.0L engine, 700-850 CFM is typical. For a turbocharged 2.5L, you’ll want 900-1,100 CFM. Always match the CFM rating to your engine’s airflow needs - not to a number you heard online.