Transformers and Power Supplies
Transformer Efficiency Calculator
This calculator evaluates transformer efficiency for a single transformers and power supplies scenario. It uses output power and input power and shows the equation behind the displayed value.
Enter values for Transformer efficiency
Do not mix values recorded under different conditions.
Before entering values
Identify RMS, average, peak, and rectified quantities explicitly. Do not combine a worst-case value with unrelated nominal data.
A denominator entry cannot be zero. A prefix error can move the result by several orders of magnitude. The broader analysis may also use Battery Round-Trip Efficiency Calculator.
- Output power
- Default example: 920 W. Enter output power in W.
- Input power
- Default example: 1000 W. Enter input power in W.
Transformer efficiency: calculation method
Here, Transformer efficiency is obtained from efficiency = output ÷ input × 100. Only Output power and Input power enter the numerical result.
The defaults produce 92.00%. Replace them with measurements from one operating state.
Calculate transformer efficiency from output power and input power. For the companion power-supply efficiency calculation, open Power Supply Efficiency Calculator.
Transferring the result
Archive output power and input power with transformer efficiency. Identify the instrument, rating, or assumption behind each entry.
Pass transformer efficiency at its stored precision for dependent calculations. Keep a separate displayed value if reporting precision differs.
What the number means
Interpret Transformer efficiency on the same basis used for the source values. Compare it with voltage stress, current stress, ripple, loss, regulation, and temperature.
Save the raw entries before testing another scenario.
Common entry mistakes
Values recorded at different operating points should not share one case.
Compare the magnitude with a quick independent estimate.
What the formula leaves out
Measure under the intended load and temperature.
Depending on the application, account for diode loss, ESR, regulation, ripple current, and thermal resistance. Use measurements, manufacturer data, or another calculation for effects that can change the decision.
Identify RMS, average, peak, and rectified quantities explicitly.
Trace the result back to its source
Review input power and the remaining entries as one case. If one value belongs to another temperature, load, or time period, separate the scenarios.
Use transformer efficiency alongside a no-load, nominal-load, and limiting-load case. Preserve the unrounded number until all dependent calculations and comparisons are complete.
Keep a baseline and vary the least certain measurement first. A separate analysis may be needed for diode loss, ESR, regulation, ripple current, and thermal resistance.
Before relying on the answer
What explains a gap between calculated and observed transformer efficiency?
Recheck units and operating state before investigating isolation, creepage, waveform shape, and manufacturer operating limits.
How should I compare two Transformer Efficiency cases?
Change one uncertain entry at a time and preserve the baseline. Record waveform, frequency, load level, and winding or device temperature.