Ridge vents
A wide variety of vents that allow excess heat and moisture to escape at the most effective location - the ridge.
Attic ventilation calculator
How to use the GAF vent calculator
Step 1: Measure
Measure the length and width of the attic floor space to be ventilated.
Step 2: Calculate
Enter the length and width or the total square footage of the attic floor space to be ventilated.
Step 3: Identify
See recommended quantities below for each GAF Ventilation Product (typically rounded up).
Let’s get started
Use this calculator to help determine the proper amount of balanced attic ventilation based on minimum U.S. FHA 1/300 guidelines.*
Suggestions for 900 sq. ft. Area
Numbers shown represent the recommended total number of units required for a single product.
384 Minimum Sq. In. of Net Free Area of
exhaust needed at or near the ridge.
And
384 Minimum Sq. In. of Net Free Area
of intake needed at or near the soffit.
Please Note:
Some local building codes require the 1/150 attic
ventilation rule, which increases the minimum attic ventilation needed. Always
consult local building code requirements in your area for details.
Note: N/R = not recommended
Exhaust Ventilation
| Product | Lineal Feet Required |
|---|---|
| Cobra® RidgeRunner® | 31' |
| Cobra® Rigid Vent 3™ | 22' |
| Cobra® SnowCountry® | 22' |
| Cobra® SnowCountry® Advanced | 22' |
| Cobra® Hip Vent | 43' |
| TruSlate® Ridge Vent | 43' |
Product
Cobra® RidgeRunner®
Lineal Feet Required
31'
Product
Cobra® Rigid Vent 3™
Lineal Feet Required
22'
Product
Cobra® SnowCountry®
Lineal Feet Required
22'
Product
Cobra® SnowCountry® Advanced
Lineal Feet Required
22'
Product
Cobra® Hip Vent
Lineal Feet Required
22'
Product
TruSlate® Ridge Vent
Lineal Feet Required
22'
| Product | Lineal Feet Required |
|---|---|
| Cobra® Exhaust Vent - Hand Nailable | 31' |
| Cobra® Exhaust Vent - Nail Gunnable | 22' |
Product
Cobra® Exhaust Vent - Hand Nailable
Lineal Feet Required
31'
Product
Cobra® Exhaust Vent - Nail Gunnable
Lineal Feet Required
22'
| Product | Lineal Feet Required |
|---|---|
| AR10 | 31' |
Product
AR10
Lineal Feet Required
31'
| Product | Number Required |
|---|---|
| RT65 Plastic Square - Top | 31 |
| IR61 Plastic Slant - Back | 31 |
| R50/RV50 Metal Utility | 31 |
| IR65 Plastic Slant - Back | 31 |
| SSB960 Metal Super Slant - Back | 31 |
| HCD144 High-Capacity Dome Vent | 31 |
Product
RT65 Plastic Square - Top
Number Required
31
Product
IR61 Plastic Slant - Back
Number Required
31
Product
R50/RV50 Metal Utility
Number Required
31
Product
IR65 Plastic Slant - Back
Number Required
31
Product
SSB960 Metal Super Slant - Back
Number Required
31
Product
HCD144 High-Capacity Dome Vent
Number Required
31
Intake Ventilation
| Product | Lineal Feet Required |
|---|---|
| Cobra IntakePro® | 31' |
Product
Cobra IntakePro®
Lineal Feet Required
31'
Product
Cobra® Fascia Vent (Mesh Roll) 1"
Lineal Feet Required
22'
Product
Cobra® Fascia Vent (Mesh Roll) 1.5"
Lineal Feet Required
22'
| Product | Number Required |
|---|---|
| LSV8 Metal Continuous Soffit Vents (Lineal Feet) | 31' |
| EAP 4x12 Plastic Soffit Vents | 31 |
| EAC 16x4 Metal Soffit Vents | 31 |
| EAC 16x8 Metal Soffit Vents | 31 |
| EmberShield® Closeable Soffit Vents | 31 |
Product
LSV8 Metal Continuous Soffit Vents
Number Required
31
Product
EAP 4x12 Plastic Soffit Vents
Number Required
22
Product
EAC 16x4 Metal Soffit Vents
Number Required
22
Product
EAC 16x8 Metal Soffit Vents
Number Required
22
Product
EmberShield® Closeable Soffit Vents
Number Required
22
Intake or Exhaust Ventilation
Note: Gable louvers are typically installed in pairs
| Product | Number Required |
|---|---|
| DA 12x12 | 31 |
| DA 12x18 | 31 |
| DA 14x24 | 31 |
| DA 18x24 | 31 |
| DA 24x30 | 31 |
Product
DA 12x12
Number Required
31
Product
DA 12x18
Number Required
31
Product
DA 14x24
Number Required
31
Product
DA 18x24
Number Required
32
Product
DA 24x30
Number Required
33
| Product | Number Required |
|---|---|
| SL 8x8 | 31 |
| SL 12x12 | 31 |
| SL 12x18 | 31 |
| SL 18x24 | 31 |
Product
SL 8x8
Number Required
34
Product
SL 12x12
Number Required
35
Product
SL 12x18
Number Required
36
Product
SL 14x24
Number Required
37
Product
SL 18x24
Number Required
38
| Product | Number Required |
|---|---|
| RLSC 2" | 31 |
| RLSC 3" | 31 |
| RLSC 4" | 31 |
Product
RLSC 2"
Number Required
39
Product
RLSC 3"
Number Required
40
Product
RLSC 4"
Number Required
41
Exhaust Ventilation
| Product | Number Required |
|---|---|
| ERV4 | 31 |
| ERV5 & Wi-Fi ERV5QCT | 22 |
| ERV6 | 22 |
| EZ Cool™ EZCR1 | 22 |
Product
ERV4
Number Required
31
Product
ERV5 & Wi-Fi ERV5QCT
Number Required
22
Product
ERV6
Number Required
31
Product
EZ Cool™ EZCR1
Number Required
31
| Product | Number Required |
|---|---|
| EGV5 & Wi-Fi EGV5QCT | 31 |
| EGV6 | 22 |
| EZ Cool™ EZCG1 | 22 |
Product
EGV5 & Wi-Fi EGV5QCT
Number Required
31
Product
EGV6
Number Required
31
Product
EZ Cool™ EZCG1
Number Required
31
| Product | Number Required |
|---|---|
| Solar & Dual-Powered Roof (ERVSOLAR / ERVHYBRID) | 31 |
| Solar-Powered Gable (PGSOLAR) | 22 |
| High-Power Solar & Dual-Powered Roof (PRSOLAR2 / PRHYBRID2) | 22 |
Product
Solar & Dual-Powered Roof (ERVSOLAR / ERVHYBRID)
Number Required
31
Product
Solar-Powered Gable (PGSOLAR)
Number Required
31
Product
High-Power Solar & Dual-Powered Roof (PRSOLAR2 / PRHYBRID2)
Number Required
31
| Product | Number Required |
|---|---|
| 12" | 31 |
| 14" | 22 |
Product
12"
Number Required
31
Product
14"
Number Required
31
Intake Ventilation
| Product | Lineal Feet Required |
|---|---|
| with ERV4 | 31' |
| with ERV5 & Wi-Fi ERV5QCT | 22' |
| with ERV6 | 31' |
| with EZ Cool™ EZCR1 | 31' |
| with EGV5 & Wi-Fi EGV5QCT | 22' |
| with EGV6 | 31' |
| with EZ Cool™ EZCG1 | 31' |
| with Solar & Dual-Powered Roof | 22' |
| with Solar-Powered Gable | 22' |
| with High-Power Solar & Dual-Powered Roof | 22' |
| with 12" Wind Turbine | 22' |
| with 14" Wind Turbine | 22' |
Product
with ERV4
Lineal Feet Required
31'
Product
with ERV5 & Wi-Fi ERV5QCT
Lineal Feet Required
31'
Product
with ERV6
Lineal Feet Required
31'
Product
with EZ Cool™ EZCR1
Lineal Feet Required
31'
Product
with EGV5 & Wi-Fi EGV5QCT
Lineal Feet Required
31'
Product
with EGV6
Lineal Feet Required
31'
Product
with EZ Cool™ EZCG1
Lineal Feet Required
31'
Product
with Solar & Dual-Powered Roof
Lineal Feet Required
31'
Product
with Solar-Powered Gable
Lineal Feet Required
31'
Product
with High-Power Solar & Dual-Powered Roof
Lineal Feet Required
31'
Product
with 12" Wind Turbine
Lineal Feet Required
31'
Product
with 14" Wind Turbine
Lineal Feet Required
31'
| Product | Lineal Feet Required |
|---|---|
| with ERV4 | 31' |
| with ERV5 & Wi-Fi ERV5QCT | 22' |
| with ERV6 | 31' |
| with EZ Cool™ EZCR1 | 31' |
| with EGV5 & Wi-Fi EGV5QCT | 22' |
| with EGV6 | 31' |
| with EZ Cool™ EZCG1 | 31' |
| with Solar & Dual-Powered Roof | 22' |
| with Solar-Powered Gable | 22' |
| with High-Power Solar & Dual-Powered Roof | 22' |
| with 12" Wind Turbine | 22' |
| with 14" Wind Turbine | 22' |
Product
with ERV4
Lineal Feet Required
31'
Product
with ERV5 & Wi-Fi ERV5QCT
Lineal Feet Required
31'
Product
with ERV6
Lineal Feet Required
31'
Product
with EZ Cool™ EZCR1
Lineal Feet Required
31'
Product
with EGV5 & Wi-Fi EGV5QCT
Lineal Feet Required
31'
Product
with EGV6
Lineal Feet Required
31'
Product
with EZ Cool™ EZCG1
Lineal Feet Required
31'
Product
with Solar & Dual-Powered Roof
Lineal Feet Required
31'
Product
with Solar-Powered Gable
Lineal Feet Required
40'
Product
with High-Power Solar & Dual-Powered Roof
Lineal Feet Required
31'
Product
with 12" Wind Turbine
Lineal Feet Required
31'
Product
with 14" Wind Turbine
Lineal Feet Required
31'
| Product | Number Required |
|---|---|
| with ERV4 | 31 |
| with ERV5 & Wi-Fi ERV5QCT | 22 |
| with ERV6 | 31 |
| with EZ Cool™ EZCR1 | 31 |
| with EGV5 & Wi-Fi EGV5QCT | 22 |
| with EGV6 | 31 |
| with EZ Cool™ EZCG1 | 31 |
| with Solar & Dual-Powered Roof | 22 |
| with Solar-Powered Gable | 22 |
| with High-Power Solar & Dual-Powered Roof | 22 |
| with 12" Wind Turbine | 22 |
| with 14" Wind Turbine | 22 |
Product
with ERV4
Number Required
31
Product
with ERV5 & Wi-Fi ERV5QCT
Number Required
31
Product
with ERV6
Number Required
31
Product
with EZ Cool™ EZCR1
Number Required
31
Product
with EGV5 & Wi-Fi EGV5QCT
Number Required
31
Product
with EGV6
Number Required
31
Product
with EZ Cool™ EZCG1
Number Required
31
Product
with Solar & Dual-Powered Roof
Number Required
31
Product
with Solar-Powered Gable
Number Required
49
Product
with High-Power Solar & Dual-Powered Roof
Number Required
31
Product
with 12" Wind Turbine
Number Required
31
Product
with 14" Wind Turbine
Number Required
31
| Product | Number Required |
|---|---|
| with ERV4 | 31 |
| with ERV5 & Wi-Fi ERV5QCT | 22 |
| with ERV6 | 31 |
| with EZ Cool™ EZCR1 | 31 |
| with EGV5 & Wi-Fi EGV5QCT | 22 |
| with EGV6 | 31 |
| with EZ Cool™ EZCG1 | 31 |
| with Solar & Dual-Powered Roof | 22 |
| with Solar-Powered Gable | 22 |
| with High-Power Solar & Dual-Powered Roof | 22 |
| with 12" Wind Turbine | 22 |
| with 14" Wind Turbine | 22 |
Product
with ERV4
Number Required
31
Product
with ERV5 & Wi-Fi ERV5QCT
Number Required
31
Product
with ERV6
Number Required
31
Product
with EZ Cool™ EZCR1
Number Required
31
Product
with EGV5 & Wi-Fi EGV5QCT
Number Required
31
Product
with EGV6
Number Required
31
Product
with EZ Cool™ EZCG1
Number Required
31
Product
with Solar & Dual-Powered Roof
Number Required
31
Product
with Solar-Powered Gable
Number Required
58
Product
with High-Power Solar & Dual-Powered Roof
Number Required
31
Product
with 12" Wind Turbine
Number Required
31
Product
with 14" Wind Turbine
Number Required
31
| Product | Number Required |
|---|---|
| with ERV4 | 31 |
| with ERV5 & Wi-Fi ERV5QCT | 22 |
| with ERV6 | 31 |
| with EZ Cool™ EZCR1 | 31 |
| with EGV5 & Wi-Fi EGV5QCT | 22 |
| with EGV6 | 31 |
| with EZ Cool™ EZCG1 | 31 |
| with Solar & Dual-Powered Roof | 22 |
| with Solar-Powered Gable | 22 |
| with High-Power Solar & Dual-Powered Roof | 22 |
| with 12" Wind Turbine | 22 |
| with 14" Wind Turbine | 22 |
Product
with ERV4
Number Required
31
Product
with ERV5 & Wi-Fi ERV5QCT
Number Required
31
with ERV6
Number Required
31
with EZ Cool™ EZCR1
Number Required
31
with EGV5 & Wi-Fi EGV5QCT
Number Required
31
with EZ Cool™ EZCG1
Number Required
31
with Solar & Dual-Powered Roof
Number Required
31
with Solar-Powered Gable
Number Required
67
with High-Power Solar & Dual-Powered Roof
Number Required
31
with 12" Wind Turbine
Number Required
31
with 14" Wind Turbine
Number Required
31
| Product | Number Required |
|---|---|
| with ERV4 | 31 |
| with ERV5 & Wi-Fi ERV5QCT | 22 |
| with ERV6 | 31 |
| with EZ Cool™ EZCR1 | 31 |
| with EGV5 & Wi-Fi EGV5QCT | 22 |
| with EGV6 | 31 |
| with EZ Cool™ EZCG1 | 31 |
| with Solar & Dual-Powered Roof | 22 |
| with Solar-Powered Gable | 22 |
| with High-Power Solar & Dual-Powered Roof | 22 |
| with 12" Wind Turbine | 22 |
| with 14" Wind Turbine | 22 |
Product
with ERV4
Number Required
31
Product
with ERV5 & Wi-Fi ERV5QCT
Number Required
31
Product
with ERV6
Number Required
31
Product
with EZ Cool™ EZCR1
Number Required
31
Product
with EGV5 & Wi-Fi EGV5QCT
Number Required
31
Product
with EGV6
Number Required
31
Product
with EZ Cool™ EZCG1
Number Required
31
Product
with Solar & Dual-Powered Roof
Number Required
31
Product
with Solar-Powered Gable
Number Required
75
Product
with High-Power Solar & Dual-Powered Roof
Number Required
31
Product
with 12" Wind Turbine
Number Required
31
Product
with 14" Wind Turbine
Number Required
31
Understanding your vent calculation results
Properly measuring the attic floor space is an important first step to help achieve a balanced and effective attic ventilation system. Effective ventilation can help reduce excessive attic heat and moisture, avoid premature roof system degradation, and limit the growth of harmful mold and mildew. Learn more about how calculations work and what products to use.
Watch to learn: the 1:300 attic ventilation rule*
The U.S. Federal Housing authority recommends a minimum of 1 square foot of ventilation for every 300 square feet of attic space, split evenly between intake and exhaust. Watch this video to learn more.
*This calculator is provided for general educational purposes and does not constitute professional engineering or architectural advice. The 1/300 rule may not be suitable for every architectural design or climate zone. Always review local building codes for specific requirements in your area and consult with a licensed design professional for attic ventilation questions.
Watch to learn: choosing roof vent products
Watch this video to learn about choosing the right attic ventilation components for you. Also see our vent solutions guide.
GAF vent products
Power attic vents
Serious off-ridge ventilation power with advanced technology.
Intake vents
A broad line of rooftop intake vent products for your residential roof system.
Soffit vents
Products that help allow critical intake ventilation to enter the attic.
GAF Master Flow™ Off-Ridge Exhaust vents
Whatever style of roof you’re working with, GAF has the right off-ridge ventilation product for the job.
Learn more about roof ventilation on our blog
Most common roof vent types
How roof vents work and what benefits they can bring your house.
Vent types
Five common ventilation mistakes
Common ventilation installation mistakes and how to avoid them.
What to avoid
What is a ridge vent, and when is one used?
A system with vents at the peak and intakes at the soffit.
About ridge vents
FAQs about calculating attic ventilation
Balanced attic ventilation means an equal amount of air entering and exiting. It helps reduce damaging heat and moisture in the attic, it helps avoid premature roof system deterioration, and helps limit the growth of harmful mold and mildew.
While some products may be more common in certain geographic areas, roof design typically drives the type of vent product used. For roof designs with ample ridge area, ridge vents are most commonly used. For hip roofs or more "cut-up" roofs, off-ridge vents, either static or powered, are typically the most popular choices.
This particular calculator is designed to take the length and width of your attic floor space and convert it to the recommended amounts of GAF vent products based on the minimum 1:300 balanced ventilation rule.
Simply measure the length and width of the attic floor space to be vented and multiply the two together for the square footage. This will help determine the minimum amount of ventilation for the attic space.
Balanced attic ventilation means an equal amount of air entering and exiting. It helps reduce damaging heat and moisture in the attic, it helps avoid premature roof system deterioration, and helps limit the growth of harmful mold and mildew.
GAF offers a comprehensive portfolio of ridge and off-ridge ventilation products. GAF has the ventilation solution for virtually any type of structure and climate in North America.