100A service is the minimum for a modern home and can be adequate for smaller homes without electric heat or EV charging. 200A is the practical standard for most homes today, especially with central air, electric appliances, or a planned EV charger. Larger homes or homes with multiple major electric loads may need more than 200A.
What the amp rating actually means
The amp rating of your electrical panel is the total amount of electrical current your home's service can safely deliver at once. It's not about any single device — it's the ceiling on everything running simultaneously across the whole house. A 100A panel has less than half the capacity of a 200A panel.
When 100A is genuinely enough
A smaller home without electric heat, without a large HVAC system, and without plans for an EV charger or major electric appliances can sometimes run comfortably on 100A service, especially older homes with gas heat and gas water heating that were never asked to carry much electric load. The key question isn't the panel's age — it's whether the home's actual current and near-future electric demand fits within it.
Why 200A has become the practical default
Central air conditioning, electric ranges, electric dryers, larger kitchens with more built-in appliances, and increasingly, EV charging, all add up faster than older 100A-era homes were designed for. 200A gives most homes comfortable headroom for these loads plus some room to add more later without another upgrade.
When to consider more than 200A
Larger homes, homes with multiple HVAC zones, a pool or hot tub, a workshop, or plans for multiple EV chargers may need 300A or 400A service. This is a smaller share of homes, but it's not just an estate-home consideration — a large addition or a home with several major electric systems can push past what 200A comfortably supports.
The real answer comes from a load calculation, not a rule of thumb
None of the above replaces an actual load calculation based on your specific home, current appliances, and any planned additions like an EV charger. Two homes of similar size can have very different real answers depending on how they're actually used. That calculation — not the panel's current age or a general rule — is what should drive the sizing decision.
Not sure if this applies to your home? We're happy to take a look.
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