Quick Answer: Can MERV, EN779, and ISO 16890 Be Converted Directly?
Not exactly.
A filter conversion table is useful for communication and quotation, but MERV, EN779, and ISO 16890 are not perfectly interchangeable.
Why the Conversion Is Only Approximate
MERV is based on ASHRAE 52.2 and uses a numbered rating system.
EN779 used older European classes such as G4, M5, F7, F8, and F9.
ISO 16890 classifies filters by efficiency against particulate matter groups such as ePM1, ePM2.5, ePM10, and ISO Coarse.
The test method, particle size range, discharge process, and reporting format are different.
Pressure drop and rated airflow still need to be confirmed separately.
Key takeaway: use the chart for initial selection, then confirm the actual filter test report before ordering.
MERV to ISO 16890 Chart for HVAC Air Filters
The table below is a practical MERV to ISO 16890 chart for general ventilation filters. It is intended for procurement communication, not as an official one-to-one certification table.
Important: HEPA and ULPA filters should normally be specified under EN 1822 or ISO 29463, not only by MERV, EN779, or ISO 16890. For example, H13 and H14 filters are not simply "higher MERV filters."
EN779 vs MERV: Why Old G4 and F7 Names Still Appear
Many existing HVAC drawings still use EN779 classes because the systems were designed years ago.
Common old names include:
G3
G4
M5
M6
F7
F8
F9
These terms are short and familiar. Maintenance teams still use them because they appear on old filter labels, spare parts lists, and AHU manuals.
But for new international projects, ISO 16890 is usually a clearer way to specify general ventilation filters.
The Main Difference
EN779 classified general ventilation filters using older coarse, medium, and fine filter classes. ISO 16890 describes filter performance using particulate matter groups:
•ISO Coarse
•ISO ePM10
•ISO ePM2.5
•ISO ePM1
This is more useful when buyers are trying to connect air filtration to fine dust control, indoor air quality, and PM-related project requirements.
Why We Should Stop Using Only "G4" or "F7"
Old EN779 names are not wrong as historical references. The problem is using them as the only specification.
For example:
"G4 filter" does not tell the supplier the exact ISO Coarse value.
"F7 bag filter" does not confirm whether the filter meets a specific ePM1 percentage.
"MERV 13 replacement for F7" may be close in many cases, but it still needs a datasheet check.
Different filter structures can reach a similar class with different pressure drop and service life.
Our engineers often see this problem in retrofit projects. A customer sends an old label saying "F7," but the consultant's new document asks for ISO ePM1 60%. If the supplier only copies the old F7 label, the submitted filter may not match the updated project requirement.
A better specification would be:
Synthetic bag filter, ISO ePM1 60%, 592 × 592 × 600 mm, rated airflow 3400 m³/h, initial resistance ≤120 Pa, galvanized frame, downstream gasket.
That is much clearer than simply writing:
How ISO 16890 Names Work
ISO 16890 looks more complicated at first, but it gives more useful information for modern HVAC projects.
ISO Coarse
ISO Coarse filters are used for larger dust particles and basic equipment protection.
Typical use:
•AHU pre-filter section
•FCU intake filter
•Washable metal mesh filter
•Nylon mesh filter
•G3/G4 replacement discussions
ISO ePM10
ISO ePM10 filters target particles in the PM10 range. They are often used in commercial ventilation systems where moderate dust control is required.
Typical use:
•Commercial HVAC systems
•Schools
•Shopping malls
•Hotels
•General AHU filtration
ISO ePM2.5
ISO ePM2.5 filters provide better fine particle control than coarse filters. They are often selected for urban building ventilation and better indoor air quality.
Typical use:
•Office buildings
•Public facilities
•Commercial AHU second-stage filtration
•Medium filter sections
ISO ePM1
ISO ePM1 filters are used where finer particle control is required. This category is often discussed when replacing old F7, F8, or F9 filters.
Typical use:
•Better indoor air quality projects
•Airports
•Healthcare support areas
•High-grade commercial buildings
•Pre-HEPA filtration
Practical EN779 to ISO 16890 Reference
For old European specifications, the table below can help buyers update EN779 classes into ISO 16890 language.
| Old EN779 Class | Practical ISO 16890 Reference | Typical Use |
| G3 | ISO Coarse 45–60% | Basic pre-filtration |
| G4 | ISO Coarse 60–85% | Common pre-filter replacement |
| M5 | ePM10 40–60% | Low-to-medium HVAC filtration |
| M6 | ePM2.5 50–65% or ePM10 60–80% | Medium HVAC filtration |
| F7 | ePM1 50–65% | Better fine particle control |
| F8 | ePM1 65–80% | High IAQ HVAC applications |
| F9 | ePM1 80–90% | High-performance fine filtration |
This table should be treated as a selection guide. The final filter should still be confirmed by the manufacturer's datasheet and test report.
Common Mistakes in Air Filter Efficiency Conversion
Mistake 1: Treating the Conversion Chart as an Exact Standard
A MERV to ISO 16890 chart is useful, but it is not a substitute for laboratory data.
Two filters may fall into the same general conversion range but have different:
•Initial resistance
•Final resistance
•Rated airflow
•Dust holding capacity
•Frame design
•Media structure
•Gasket position
•Service life
Mistake 2: Ignoring Pressure Drop
A higher efficiency filter usually creates more resistance, although the exact value depends on media and structure.
If the filter pressure drop is too high, the AHU may lose airflow. That can affect room pressure, cooling capacity, ventilation rate, and energy consumption.
Always check:
•Rated airflow
•Initial resistance
•Recommended final resistance
•Fan capacity
•Filter depth
•Available installation space
Efficiency and pressure drop must be reviewed together.
Mistake 3: Replacing a Deep Bag Filter with a Thin Panel Filter
A 46 mm pleated filter and a 600 mm bag filter may sometimes be discussed in a similar efficiency range, but they do not behave the same in operation.
Filter depth affects:
•Dust holding capacity
•Service life
•Pressure drop curve
•Maintenance frequency
•Airflow stability
•For commercial AHUs, structure matters as much as class.
Mistake 4: Confusing MERV 13 with H13
•MERV 13 and H13 are not the same thing.
•MERV 13 is a general HVAC filter rating under ASHRAE 52.2.
•H13 is a HEPA filter class under EN 1822 or ISO 29463.
•This is a serious procurement mistake. A MERV 13 filter is not a HEPA filter.
Mistake 5: Forgetting the Pre-Filter Stage
•A high-efficiency final filter without a proper pre-filter may load too quickly.
•For many AHUs, a staged system works better:
•ISO Coarse pre-filter
•ePM2.5 or ePM1 medium filter
•HEPA filter only where required
This reduces maintenance cost and helps protect the final filter.
How International Buyers Should Convert Filter Specifications
Use a structured process instead of guessing from one rating system to another.
Step 1: Identify the Current Standard
Check whether the existing requirement is written as:
•MERV 8, MERV 13, MERV 14
•G4, M5, F7, F8, F9
•ISO Coarse, ePM10, ePM2.5, ePM1
•H13 or H14
Do not mix HEPA and general HVAC filter classes.
Step 2: Confirm the Application
Ask where the filter will be used:
•AHU pre-filter section
•Medium filter section
•Final HVAC filter
•Cleanroom make-up air unit
•Food processing air supply
•Healthcare support ventilation
•Industrial ventilation system
•Pre-HEPA stage
The same efficiency class may require a different structure depending on the application.
Step 3: Use the Conversion Table as a Starting Point
For example:
•MERV 8 may point to ISO Coarse or ePM10 range.
•MERV 13 may point to ISO ePM1 50–65%.
•F7 may point to ISO ePM1 50–65%.
•F8 may point to ISO ePM1 65–80%.
Then ask for the actual datasheet.
Step 4: Confirm Airflow and Pressure Drop
This is where many quotation mistakes happen.
Before ordering, confirm:
•Rated airflow per filter
•Initial resistance
•Recommended final resistance
•Filter face velocity
•AHU fan capacity
•Operating pressure limit
•Expected maintenance interval
A filter with the right class but wrong pressure drop is still the wrong filter.
Step 5: Confirm Size and Construction
Check:
•Length × width × depth
•Frame material
•Header frame or box frame
•Gasket position
•Pocket depth
•Media type
•Filter orientation
•Clips or holding frame compatibility
•Packaging requirement
For project orders, photos and drawings are very helpful.
Recommended Specification Format for International Orders
To avoid confusion, write filter requirements in this format:
Filter type + size + standard + efficiency class + airflow + initial resistance + frame material + gasket position + quantity
•Example 1: Pre-Filter
Pleated pre-filter, 592 × 592 × 46 mm, ISO Coarse 70%, rated airflow 3400 m³/h, initial resistance ≤50 Pa, galvanized frame, no gasket, 200 pcs.
•Example 2: Medium Bag Filter
Synthetic bag filter, 592 × 592 × 600 mm, ISO ePM1 60%, rated airflow 3400 m³/h, initial resistance ≤120 Pa, galvanized header frame, downstream gasket, 100 pcs.
•Example 3: Compact Filter
V-bank compact filter, 592 × 592 × 292 mm, ISO ePM1 80%, rated airflow 3400 m³/h, initial resistance ≤140 Pa, plastic frame, optional gasket, 50 pcs.
This format gives the supplier enough information to quote accurately and avoid wrong substitutions.