How to Determine Your Electrical Service Amps

Knowing the amperage of your electrical service is important for ensuring your home’s electrical system can safely handle the power needs of your home’s appliances and equipment. Determining your service amps can prevent you from overloading your electrical system and help you plan for any service upgrades you may need in the future. Here is a comprehensive guide on how to determine the amperage of your home’s electrical service.

Understanding Electrical Service and Amperage

Your home’s electrical service refers to the incoming power supply from your electric utility company. This incoming power comes into your home through service conductors that connect to your home’s main service panel, also known as your breaker box or load center.

The service panel contains circuit breakers that distribute power to the various branch circuits throughout your home. The size of the electrical service conductors, service panel, and main circuit breaker determines the amperage available to your home.

Amperage (amps) is a measurement of the amount of electric current flowing through a wire or electrical system. The higher the amps, the more power that is available to operate lights, appliances, and equipment in your home. Many factors determine how many amps your electrical service needs to provide, which we’ll cover below.

Checking Your Main Circuit Breaker

The easiest way to determine your service amperage is to check the rating on your main circuit breaker located in your main service panel. This main breaker controls all the power entering your home and acts as the master shutoff switch for your electrical system.

The main breaker is usually the largest breaker in your panel and is commonly rated at 100, 150, 200, or 400 amps for residential services. Find the number printed on the face of the main circuit breaker and that is the amperage capacity for your electrical service.

Main circuit breaker

The main circuit breaker rating indicates your service amps.

If you don’t have a main breaker, your amperage may be shown on a label inside the service panel. If not labeled, you’ll need to use one of the following methods to determine your service size.

Checking Your Electric Meter

Another way to identify your service amps is to check the rating printed on your home’s electric meter and meter base where the service cables connect. This rating indicates the capacity of the service conductors that feed power into your main panel.

Most standard residential meters are rated up to 200, 320, 400 amps. This rating on your meter or service entry cables gives you the overall amp capacity coming into your home, even if your main breaker is lower.

Electric meter amperage

The amperage rating on your electric meter shows your service capacity.

If you have an older knob and tube meter without a rating, you’d need to count the number of service wires feeding the meter. Four or more service wires typically indicates at least a 60 amp service.

Calculating your Electrical Load

You can also determine your service amps by calculating the estimated electric load in your home based on the size and number of appliances and equipment.

Add up the nameplate amp ratings for all large appliances and equipment such as electric range, oven, washer/dryer, HVAC system, hot water heater, pool equipment, etc. Then count general circuits for lights and outlets estimating 4-8 amps per circuit. That gives you a general total electric load which you can compare to typical service sizes:

  • 60 amps for a small home with basic appliances and gas heat
  • 100 amps for an average 1500 sq ft home with electric range and AC
  • 150 – 200 amps for a larger home with central AC, electric appliances, and expanded needs
  • 320 – 400 amps for larger luxury homes, additions, or home services with heavy electric loads.

Consult an electrician if you are unsure of your home’s electric load requirements. They can conduct a detailed load calculation to recommend the proper service size to handle your home’s electrical needs.

Hiring an Electrician

If you are unable to determine your service amperage using the methods above, the best option is to hire a licensed electrician to evaluate your home’s electrical system.

Electricians have the tools, expertise, and experience necessary to properly identify your existing service capacity. They will check your panel, meter, number of service wires, and electric load to determine your amperage.

Hiring an electrician is especially important if you have an older home or suspect your current service may be insufficient for your household needs. The electrician can assess if your system needs upgrades, repairs, or rewiring.

When hiring an electrician:

  • Look for licensed professionals experienced in residential electrical work.
  • Ask for references from past work and check reviews online.
  • Get quotes from at least 3 electricians before choosing one.
  • Confirm they are bonded and insured for safety.
  • Ask about charges for full evaluation and getting a service amperage report.

Getting professional input provides you peace of mind your electrical system is sized properly and safely for your home’s electricity requirements.

Typical Electrical Service Sizes

To give you a better understanding of service capacities, here are some typical amperage sizes:

  • 60 Amps – Typical for smaller, older homes with basic appliances and lighting. Not suitable for larger homes with modern electric loads.
  • 100 Amps – Common in average 1500 sq ft homes built from 1950s-1980s. Allows for adequate power for lighting, outlets, electric stove, heat pump or AC, appliances and some large power tools.
  • 150 Amps – Found in mid-sized homes built after 1960. Safely handles higher electric loads from larger appliances, central AC, electric oven, washer/dryer, and other equipment.
  • 200 Amps – Standard for new home construction and renovations today. Provides capacity for high demand from multiple ACs, home electronics, appliances, expanded lighting, outbuildings and EV chargers. Future-proofs your home for expansion.
  • 320-400 Amps – Seen in larger luxury homes over 4000 sq ft. Allows for very large electric loads from multiple AC units, pool and spa equipment, workshop tools, home theater systems, wine coolers, etc.

While 200 amps is common in modern homes, an experienced electrician can determine the right service size specific to your home’s electrical system needs and future growth.

Upgrading Electrical Service Amps

If your existing service amperage seems lower than recommended for your home’s size and electricity usage, you may benefit from a service panel upgrade.

Signs you may need a service upgrade include:

  • Frequent tripping of the main breaker or overload of individual circuits
  • Dimming or flickering lights when large appliances run
  • Needing heavy duty extension cords to run equipment in outbuildings
  • Old 60-100 amp service in a large modern home
  • Planning major home additions or renovations.

Upgrading gives you increased capacity by replacing the service wires, meter, panel and main breaker with new larger components.

Common service upgrades:

  • 100 amps upgraded to 150-200 amps
  • 150 amps upgraded to 200 amps
  • 60 amp fuse box upgraded to 100-150 amp breaker panel

The cost of an electrical service upgrade ranges from $1500 – $8000 depending on the amperage increase and complexity of the project. Upgrading provides future-proof capacity for larger homes and modern household electricity demands.

How to Determine Your Electrical Service Amps: Key Takeaways

  • Check your main circuit breaker rating in your electrical service panel. This shows your current service amps.
  • Look for the amperage printed on your electric meter or service entry cables. This is your overall service capacity.
  • Calculate your home’s estimated electrical load by adding nameplate amp ratings for all appliances and equipment. Compare total to typical service sizes.
  • Hire a licensed electrician to evaluate your existing system and determine your service amperage if you are unable to identify it yourself.
  • Standard residential service sizes are 60 amps, 100 amps, 150 amps, 200 amps for most homes. New large luxury homes may have 320-400 amps.
  • If your current service seems undersized, consider upgrades to prevent overloading and provide capacity for future electrical needs.

Frequently Asked Questions

Below are some common questions homeowners have about determining their electrical service amps:

How do I know if my home has 100 amp, 150 amp, or 200 amp service?

The main circuit breaker or electric meter will be labeled with the service amperage. If not labeled, you’ll need to count your service wires or have an electrician evaluate your full electrical system to determine your amps.

What size service do I need for a 2500 square foot home?

A 2500 square foot home will typically need 150-200 amp electrical service. 200 amps provides capacity for higher demand from larger appliances, home electronics, central AC, pool equipment, etc.

Can I increase my 100 amp service to 200 amps?

Yes, homes with 60-100 amp panels can upgrade to 200 amp service. This requires replacing the service wires, meter, panel and breaker. Cost is $2000-$4000 but provides significantly more power capacity.

How many amps are in a 100 amp service?

A 100 amp service refers to the capacity of the main service wires and panel. At 120 volts standard voltage, a 100 amp service can provide 12,000 to 20,000 total watts of power depending on demand.

Is 200 amps enough for a house?

For most homes under 3000 square feet, a 200 amp service is adequate and provides capacity for typical modern electrical loads and appliances. Larger homes may need 320-400 amp service for very high power demand.

Is 400 amp service overkill?

For very large luxury homes over 4000+ square feet with high electric loads, 400 amp service may be justified. But it is overkill for average sized homes. Adequate capacity is usually achieved with 150-200 amp service in most modern houses.


Determining your existing electrical service amps is an important first step in ensuring your home’s electrical system can handle your household needs. Check your main breaker, meter and wire count, perform load calculations, and hire an electrician if necessary.

Standard services range from 60 amps to 400 amps, with 100-200 amps meeting most homes’ electricity demand. If your current service seems insufficient, consider upgrade options for providing expanded capacity now and future growth.

With this guide, homeowners can accurately identify their electrical service specs to maintain a safe, high performing electrical system.