AC/DC Efficiency Calculator

What is AC to DC Conversion Efficiency?

Every power supply that converts mains AC to DC output loses some energy as heat during conversion. This efficiency is expressed as a percentage: (DC output power / AC input power) × 100%.

High efficiency matters for: lower electricity bills, less heat generation, smaller heatsinks, and meeting regulatory standards (ENERGY STAR, EU EcoDesign).

The Formula

Efficiency (%) = (P_DC_out / P_AC_in) × 100 Power Loss (W) = P_AC_in − P_DC_out

The 80 Plus Standard

The 80 Plus certification guarantees minimum efficiency at 20%, 50%, and 100% load:

| Rating | Efficiency at 50% load | |--------|------------------------| | 80 Plus | 80% | | Bronze | 85% | | Silver | 88% | | Gold | 90% | | Platinum | 92% | | Titanium | 94% |

How to Use This Calculator

Enter AC input power (measured at the wall socket) and DC output power (voltage × current of the DC output). Results show efficiency percentage, power loss, and the 80 Plus rating if applicable.

Practical Examples

Example 1: PC power supply: 600W AC input, 504W DC output. Efficiency = 504/600 = 84% → 80 Plus Bronze.

Example 2: Phone charger: 5W AC in, 4.2W DC out. Efficiency = 84% — good for a small charger.

Example 3: Industrial rectifier: 10kW AC, 9.5kW DC. Efficiency = 95% — excellent.