SEER Calculator

SEER Rating Chart

Understanding SEER ratings helps you choose the right AC unit for your needs and budget. The ENERGY STAR program and the U.S. Department of Energy both provide guidance on selecting efficient cooling equipment. For a complete breakdown, see our detailed SEER rating chart guide.

Note: As of January 2023, the minimum SEER rating for new AC units is 14 SEER in the northern US and 15 SEER in the southern US. Not sure what SEER rating you need? Our guide breaks down the best choice for each climate zone.

How SEER Rating Works

SEER (Seasonal Energy Efficiency Ratio) measures how efficiently an air conditioner converts electricity into cooling over a typical cooling season.

A higher SEER means more cooling per unit of electricity. For example, a 20 SEER unit uses about 30% less energy than a 14 SEER unit to provide the same cooling. You can look up certified equipment ratings in the AHRI Directory to verify manufacturer efficiency claims.

The testing methodology behind SEER ratings is defined by ASHRAE Standard 210/240 (also known as AHRI Standard 210/240), which specifies the conditions, procedures, and calculations used to determine seasonal efficiency. This standardized approach ensures that SEER ratings from different manufacturers are directly comparable.

SEER vs SEER2

In 2023, the industry introduced SEER2, which uses updated testing procedures. SEER2 ratings are typically about 4.5% lower than equivalent SEER ratings. A 14 SEER unit is roughly equivalent to 13.4 SEER2. Learn more about the differences in our guide: SEER vs SEER2 Explained.

Quick Reference Tables

Use these tables to quickly look up values for your calculations and understand typical ranges for different climates, unit sizes, and efficiency levels.

Climate Zone Cooling Hours

Annual cooling hours vary dramatically by region. This table shows the values used in our calculator:

AC Unit Size Reference

AC capacity is measured in tons, where 1 ton = 12,000 BTU/hour of cooling capacity:

Note: Actual sizing depends on many factors including insulation, windows, ceiling height, and local climate. Always have an HVAC professional perform a Manual J load calculation for accurate sizing.

Annual Operating Cost by SEER Rating

This table shows estimated annual cooling costs for a 3-ton unit at $0.15/kWh (US average):

Calculated using: Annual Cost = (36,000 BTU × hours × $0.15) ÷ (SEER × 1,000)

EER to SEER Conversion Table

Quick reference for converting between EER and SEER ratings (using SEER ≈ EER × 1.12):

SEER to SEER2 Conversion Table

As of 2023, SEER2 replaced SEER as the official efficiency metric. Use this table to convert between the two ratings (SEER2 ≈ SEER × 0.955):

Formula Reference

Our calculator uses industry-standard formulas based on the SEER efficiency metric. Here's exactly how each calculation works:

Core Energy Formula

Worked Example

Calculate annual energy use for a 3-ton, 16 SEER AC in a warm climate (1,800 hours):

Annual Cost Formula

Continuing the example above with $0.15/kWh:

Savings Formula

Payback Period Formula

EER to SEER Conversion

This is a simplified approximation. SEER is typically 10-15% higher than EER because SEER accounts for efficiency across a range of temperatures (65-104°F), while EER measures only at peak conditions (95°F outdoor, 80°F indoor, 50% humidity).

Percent Energy Reduction

For a quick estimate: going from 10 SEER to 20 SEER reduces energy by 50%. Going from 14 SEER to 21 SEER reduces energy by 33%.

These formulas align with the methodology described by the U.S. Department of Energy. SEER testing procedures are governed by AHRI Standard 210/240, which establishes uniform methods for rating the seasonal efficiency of air conditioners and heat pumps to ensure consistent, comparable ratings across all manufacturers.

Understanding Your Results

After running a calculation, here's how to interpret the numbers and what actions to consider:

Energy Savings Percentage

This shows how much less energy the higher-SEER unit uses compared to the lower-SEER unit:

Payback Period Guidelines

The payback period tells you how long it takes for energy savings to cover the upgrade cost:

Important: AC units typically last 15-20 years. A payback period longer than the expected lifespan means you won't recover the extra cost through energy savings alone.

Annual Savings Context

What different annual savings amounts mean in practice:

• Under $50/year: Minimal difference. Choose based on other factors like warranty, noise levels, or features.
• $50-150/year: Noticeable savings. Consider the upgrade if the payback period is reasonable.
• $150-300/year: Significant savings. Usually worth the higher-efficiency option in hot climates.
• Over $300/year: Substantial savings. The high-efficiency unit is likely the right choice.

When to Consider Professional Help

While this calculator provides useful estimates, consult an HVAC professional when:

• Your calculated savings seem unusually high or low for your situation
• You're unsure about your current unit's SEER rating or size
• Your home has unusual characteristics (very high ceilings, poor insulation, large windows)
• You want a proper Manual J load calculation to ensure correct sizing
• You're considering a heat pump instead of traditional AC
• You need help understanding rebates or tax credits available in your area

When Higher SEER Pays Off: Comparison Chart

This table shows the annual savings when upgrading from 14 SEER to various higher efficiencies, for a 3-ton unit at $0.15/kWh:

Key insight: In a hot climate, upgrading from 14 to 20 SEER saves $289/year. If the price difference between the units is $2,000, the payback is about 7 years - a good investment. In a mild climate, the same upgrade saves only $69/year, making the payback nearly 29 years - not economically justified.

How to Use This Calculator

Our SEER calculator includes four specialized tools, each designed to answer different questions about air conditioning efficiency and costs. Here's a step-by-step guide to getting the most accurate results from each one.

Savings Calculator Tab

Use this tab to estimate how much money you'll save by upgrading from your current AC unit to a more efficient one.

1. Select your current SEER rating - Choose the efficiency of your existing AC unit. If you don't know it, units from before 2006 are typically 10 SEER or less. Check the yellow EnergyGuide label on your outdoor unit.
2. Select your new SEER rating - Choose the efficiency of the unit you're considering. As of 2023, the minimum is 14 SEER in northern states and 15 SEER in southern states.
3. Enter your AC unit size - Measured in tons. A typical home uses a 2.5-3.5 ton unit. One ton equals 12,000 BTU of cooling capacity.
4. Select your climate zone - This automatically fills in typical annual cooling hours based on your region. You can also manually adjust the hours if you know your specific usage.
5. Enter your electricity rate - Find this on your utility bill. The US average is about $0.15/kWh, but rates vary from $0.08 (Louisiana) to $0.35+ (Hawaii, California).
6. Enter upgrade cost (optional) - If you want to calculate your payback period, enter the total cost of the new system including installation.

Tip: For the most accurate results, use your actual cooling hours from last year if you know them. Smart thermostats often track this data.

Compare SEER Tab

Use this tab when shopping for a new AC and you want to see the cost difference between two models side by side.

1. Enter SEER rating for Option A - Typically the lower-efficiency (and lower-cost) unit you're considering.
2. Enter SEER rating for Option B - The higher-efficiency (and higher-cost) unit you're considering.
3. Select unit size - Must be the same for both units to make a fair comparison.
4. Enter annual cooling hours - How many hours your AC runs per year. 1,500 is typical for moderate climates.
5. Enter electricity rate - Your cost per kilowatt-hour from your utility bill.

Tip: The annual difference multiplied by 10-15 years (typical AC lifespan) shows you the lifetime cost difference between the two units.

EER to SEER Converter Tab

Use this tab when you only have an EER rating and need to estimate the SEER, or vice versa.

1. Select conversion direction - Choose whether you're converting from EER to SEER or SEER to EER.
2. Enter the value - Type in the rating you want to convert.
3. Click Convert - The calculator uses the industry-standard approximation: SEER ≈ EER × 1.12.

When to use this: Window AC units and older central AC systems often show EER rather than SEER. SEER measures efficiency across a range of temperatures (65-104°F), while EER measures only at 95°F.

Cost Calculator Tab

Use this tab to estimate your annual cooling costs based on your specific usage pattern.

1. Enter your SEER rating - Your current or planned AC unit's efficiency rating.
2. Select unit size - Your AC capacity in tons.
3. Enter hours AC runs per day - Average hours during cooling season. 8 hours is typical; heavy usage might be 12-16 hours.
4. Enter months of cooling season - How many months you use air conditioning. Ranges from 3-4 months in northern states to 8-10 months in southern states.
5. Enter electricity rate - Your cost per kWh.

Tip: The "vs 14 SEER" result shows whether you're spending more or less than someone with a minimum-efficiency system.

Common Mistakes to Avoid

• Using default cooling hours for the wrong climate - A homeowner in Phoenix runs AC far more than someone in Seattle. Always adjust for your actual usage.
• Forgetting to update your electricity rate - The default is $0.15/kWh, but rates vary significantly. Check your most recent bill.
• Comparing different unit sizes - When comparing SEER ratings, make sure both calculations use the same tonnage.
• Not accounting for partial-year usage - The cost calculator lets you specify cooling months, which is more accurate than assuming year-round operation.

Real-World Examples

These scenarios show how different homeowners might use this calculator. All numbers are calculated using our actual formulas to help you see what results to expect for situations similar to yours.

Example 1: Phoenix Homeowner Planning an Upgrade

Maria owns a home in Phoenix, Arizona, with an aging 10 SEER air conditioner. She's considering upgrading to a 20 SEER unit. Her home has a 3-ton AC system, and she pays $0.13/kWh for electricity.

Her inputs:

• Current SEER: 10
• New SEER: 20
• Unit size: 3 tons (36,000 BTU/hr)
• Climate zone: Hot (2,500 cooling hours/year)
• Electricity rate: $0.13/kWh

Calculator results:

• Current annual energy: 9,000 kWh (36,000 × 2,500 ÷ 10,000)
• New annual energy: 4,500 kWh (36,000 × 2,500 ÷ 20,000)
• Annual savings: $585 (4,500 kWh × $0.13)
• Energy reduction: 50%
• 10-year savings: $5,850

What this means: In a hot climate with significant AC usage, doubling the SEER rating cuts energy use in half. With a $7,000 upgrade cost, Maria's payback period would be about 12 years - close to the unit's expected lifespan, making it a borderline decision. However, she may also qualify for utility rebates that could shorten this payback period.

Example 2: Georgia Family Comparing New Units

The Johnson family in Atlanta is building a new home and needs to choose between a 14 SEER unit ($4,500 installed) and an 18 SEER unit ($6,200 installed). They're getting a 2.5-ton system.

Their inputs (Compare tab):

• Option A: 14 SEER
• Option B: 18 SEER
• Unit size: 2.5 tons (30,000 BTU/hr)
• Annual cooling hours: 1,800 (warm climate)
• Electricity rate: $0.12/kWh

Calculator results:

• 14 SEER annual cost: $463 (3,857 kWh)
• 18 SEER annual cost: $360 (3,000 kWh)
• Annual difference: $103

What this means: The 18 SEER unit costs $1,700 more upfront but saves $103/year. The payback period is 16.5 years. Since AC units typically last 15-20 years, this upgrade is marginal from a pure cost perspective. However, the higher-efficiency unit also provides better humidity control, quieter operation, and higher resale value.

Example 3: Ohio Homeowner Calculating Summer Costs

David in Columbus, Ohio wants to estimate his summer cooling costs. He has a 16 SEER system, runs AC about 6 hours per day during summer, and his cooling season is 4 months.

His inputs (Cost tab):

• SEER rating: 16
• Unit size: 3 tons
• Hours per day: 6
• Cooling months: 4
• Electricity rate: $0.14/kWh

Calculator results:

• Annual cooling cost: $227
• Monthly cost (during summer): $57
• Cost per hour: $0.32
• vs 14 SEER: $32 less

What this means: David's 16 SEER unit saves him about $32/year compared to the minimum-efficiency 14 SEER option. His moderate climate and limited usage mean AC costs are a relatively small part of his energy bill.

Example 4: Florida Retirees with High Usage

Robert and Linda recently retired to Sarasota, Florida. Their 15-year-old AC (10 SEER) struggles to keep up with the heat. They're considering a 21 SEER high-efficiency unit for their 4-ton system.

Their inputs:

• Current SEER: 10
• New SEER: 21
• Unit size: 4 tons (48,000 BTU/hr)
• Climate: Hot (2,500 hours)
• Electricity rate: $0.14/kWh
• Upgrade cost: $9,500

Calculator results:

• Current annual energy: 12,000 kWh
• New annual energy: 5,714 kWh
• Annual savings: $880
• Payback period: 10.8 years
• 10-year savings: $8,800

What this means: With a large home in a hot climate, the savings are substantial. The payback period of about 11 years is within the unit's lifespan. Plus, they'll enjoy more consistent cooling, lower humidity, and potentially reduced maintenance costs with a new system.

Example 5: California Coast - When Higher SEER Isn't Worth It

Jennifer lives in San Diego where the mild coastal climate means she only runs AC about 600 hours per year. She's wondering whether to upgrade from 14 SEER to a 20 SEER unit.

Her inputs:

• Current SEER: 14
• New SEER: 20
• Unit size: 2 tons (24,000 BTU/hr)
• Climate: Mild (600 hours)
• Electricity rate: $0.25/kWh (California rates)
• Upgrade cost: $5,500

Calculator results:

• Current annual cost: $257 (1,029 kWh)
• New annual cost: $180 (720 kWh)
• Annual savings: $77
• Payback period: 71 years

What this means: Despite California's high electricity rates, Jennifer's limited AC usage makes a high-efficiency upgrade economically impractical. The 71-year payback far exceeds any AC unit's lifespan. She'd be better served by sticking with a 14-15 SEER unit and investing the savings elsewhere.

Example 6: Converting Window Unit EER to SEER

Tom has a window AC unit rated at 11 EER and wants to know what that means in SEER terms for comparison with central AC systems.

His input (Convert tab):

• Convert from: EER to SEER
• Value: 11

Calculator result:

• SEER equivalent: 12.3

What this means: Tom's window unit with 11 EER is roughly equivalent to a 12.3 SEER central AC system. Since modern central AC minimum is 14 SEER, his window unit is less efficient than even the most basic new central system - but window units are often adequate for single-room cooling.

Example 7: New Homeowner Planning for Replacement

Alex just bought a home in Nashville with a 12 SEER AC system that's 8 years old. He wants to know how much he'll save when he eventually replaces it with an 18 SEER unit.

His inputs:

• Current SEER: 12
• New SEER: 18
• Unit size: 3 tons
• Climate: Warm (1,800 hours)
• Electricity rate: $0.11/kWh

Calculator results:

• Annual savings: $119
• Energy reduction: 33%

What this means: Alex can expect to save about $119/year when he upgrades. With Tennessee's relatively low electricity rates, the annual savings are modest. He should plan for the upgrade when his current unit fails rather than replacing it early.

When to Use This Calculator

This SEER calculator helps with several important decisions about air conditioning. Here are the most common scenarios where it provides valuable insights:

Deciding Whether to Repair or Replace Your AC

If your current AC needs expensive repairs, use the Savings calculator to see how much you'd save with a new, more efficient unit. If annual savings multiplied by 10-15 years (plus repair costs avoided) exceed the price of a new system, replacement often makes sense.

Choosing Between AC Models While Shopping

When comparing units at different price points, use the Compare tab to see the annual operating cost difference. A more expensive high-SEER unit might pay for itself over time - or it might not, depending on your climate and usage.

Budgeting for Summer Energy Bills

Use the Cost calculator to estimate how much your AC will cost to operate this summer. This helps with budgeting and identifying whether efficiency upgrades are worth considering.

Evaluating a Home Before Purchase

When buying a home, check the AC's SEER rating and use this calculator to estimate operating costs. An older, inefficient unit might mean higher utility bills or a near-term replacement expense to factor into your offer.

Comparing Window Units to Central AC

Use the EER to SEER converter to compare window AC efficiency ratings (usually shown as EER) with central AC systems (shown as SEER). This helps when deciding between window units and central air.

Calculating Return on Investment for Upgrades

Enter your upgrade cost in the Savings calculator to see your payback period. If the payback is less than 10-12 years (the lower end of AC lifespan), the upgrade is typically a good investment. If it's longer, you might want to consider a mid-range SEER instead of the highest efficiency.

Verifying Contractor Estimates

HVAC contractors often quote energy savings when selling higher-SEER systems. Use this calculator to verify their estimates independently. If their numbers seem too good to be true, they might be using unrealistic assumptions.

Who Benefits Most From This Tool

• Homeowners in hot climates - With 2,000+ cooling hours per year, SEER rating differences translate to significant dollar amounts.
• Those with high electricity rates - In states like California, Hawaii, or Connecticut, efficiency improvements have bigger payoffs.
• People planning major home improvements - If you're already doing HVAC work, understanding efficiency trade-offs helps you make informed decisions.
• First-time homebuyers - Understanding operating costs helps you evaluate properties more completely.
• Landlords and property managers - Calculating operating costs helps with rental pricing and capital improvement decisions.

Trusted Resources

For further research and to verify efficiency ratings, rebates, and industry standards, consult these authoritative sources:

• U.S. Department of Energy - Energy Saver – Official federal resource for home energy efficiency guidance and tips.
• ENERGY STAR – EPA/DOE program for certified energy-efficient products and rebate information.
• AHRI Directory – Look up certified efficiency ratings for specific HVAC equipment models.
• DSIRE - Database of State Incentives for Renewables & Efficiency – Comprehensive database of energy efficiency incentives and policies by state.
• ACCA - Air Conditioning Contractors of America – Industry association with resources for finding qualified HVAC contractors.
• EIA - U.S. Energy Information Administration Electricity Data – Current electricity rates and energy statistics by state.

Related Guides

Dive deeper into SEER ratings, energy efficiency, and AC selection with our comprehensive guides:

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Frequently Asked Questions