Panel Capacity Calculator.
Determine remaining electrical panel capacity with our panel capacity calculator.
Utilization: 60% Safe Limit: 80%
Total Capacity
200 A
Used
120 A
Remaining
80 A
Safe Remaining
40 A
Frequently asked questions.
How much load can my panel handle?
Capacity depends on service size. NEC recommends keeping continuous loads below 80% of rating. Use the calculator to see your total and safe remaining capacity.
Is my panel overloaded?
If utilization exceeds 80% or breakers frequently trip, your panel may be overloaded. The calculator shows your exact utilization percentage.
How do I calculate panel capacity?
Remaining = Service Size - Existing Load. Safe remaining = (Service Size × 0.8) - Existing Load. The calculator computes both automatically.
Can I add an EV charger to my panel?
Check safe remaining capacity. If it exceeds the charger's amperage (typically 32-48A), you can likely add it without an upgrade.
What is the difference between 100A and 200A service?
200A provides double the capacity of 100A — essential for modern homes with EV chargers, central AC, and multiple large appliances.
When do I need a panel upgrade?
When utilization > 80%, adding major loads, panel is 30+ years old, or experiencing electrical issues. Use our Service Upgrade Calculator.
How much spare capacity should a panel have?
At least 20% of rated capacity for safety margin. The calculator shows your safe remaining capacity based on the 80% rule.
What is panel utilization?
Utilization = Existing Load ÷ Service Size × 100. The calculator shows this with a visual gauge — green is safe, red means an upgrade may be needed.
Can I exceed panel capacity?
No — exceeding capacity is dangerous and violates NEC. It can cause breaker trips, overheating, and fire risk. Upgrade if needed.
How is electrical panel load calculated?
Load is calculated per NEC Article 220. Use our Electrical Load Calculator for appliance-level estimates, or this panel calculator for capacity checks.
How we calculate this.
Methodology
Remaining capacity is computed as Panel Size − Existing Load. Safe remaining applies the NEC 80% rule: (Panel × 0.8) − Existing Load.
Assumptions
- Standard residential 240V single-phase service
- NEC 80% rule for continuous loads
- Existing load entered in aggregate amps
- Panel rating is the main breaker rating
Reviewed by ChargerLoad Editorial Team