Efficiency Calculator

Efficiency as a formal engineering metric entered widespread use with James Watt's steam-engine patents of the 1770s. Watt's refinement of the separate condenser took steam-engine efficiency from ~0.5% (Newcomen atmospheric engines) to ~3% — a sixfold improvement that single-handedly launched the Industrial Revolution. Electric motors introduced by Tesla and Westinghouse in the 1880s broke the 90% barrier, establishing electric drive as the efficiency benchmark for mechanical work.

The 80 Plus certification program, launched in 2004 by Ecos Consulting, reshaped PC power-supply design. Pre-2004 ATX supplies commonly operated at 60-70% efficiency at typical loads; today an 80 Plus Titanium PSU hits 94% at 50% load and 90% at 10% load. The tiered system (Bronze/Silver/Gold/Platinum/Titanium) proved that clear marketing labels could move industry behavior faster than regulation — a pattern later copied by Energy Star, DOE minimum efficiencies for lighting and appliances, and EU Ecodesign regulations.

The last 1-2% of efficiency is always disproportionately expensive: moving from 90% to 95% means halving losses, requiring synchronous rectification instead of Schottky diodes, GaN/SiC switches instead of silicon MOSFETs, and planar magnetics instead of wound transformers. That's why efficiency roadmaps typically advance in 1-2% per-decade steps rather than step changes.

Enter input power (Pin) and output power (Pout) in watts. The tool returns efficiency η = Pout/Pin as a percentage, loss power (Pin − Pout) which equals the heat that must be dissipated, and loss percentage. The in-dB readout (10·log₁₀η) is rarely used for power efficiency but appears sometimes in link-budget calculations.

Typical efficiency figures: linear regulator 30-70% (Pout/Pin = Vout/Vin), buck converter 85-97%, LLC resonant converter up to 98%, Class-AB audio amp 40-70%, Class-D amp 85-95%, tube audio amp 20-30%. For cascaded stages, multiply: η_total = η₁·η₂·η₃. Everything runs client-side; no values leave your browser.