Linear Regulator Efficiency Calculator Formula
Understand the math behind the linear regulator efficiency calculator. Each variable explained with a worked example.
Formulas Used
Efficiency
efficiency_pct = (v_out / v_in) * 100Power Wasted
power_wasted_w = (v_in - v_out) * load_current_aPower Delivered
power_delivered_w = v_out * load_current_aVariables
| Variable | Description | Default |
|---|---|---|
v_in | Input Voltage(V) | 12 |
v_out | Output Voltage(V) | 5 |
load_current_a | Load Current(A) | 1 |
How It Works
Linear Regulator Efficiency
Formula
Efficiency = V_out / V_in x 100%
Linear regulators are simple and low-noise but waste power as heat. Efficiency depends only on the voltage ratio, not on current. A 12V-to-5V linear regulator is only 42% efficient.
Worked Example
12 V input, 5 V output, 1 A load.
- 01Efficiency = 5 / 12 x 100 = 41.7%
- 02Power delivered = 5 x 1 = 5 W
- 03Power wasted = (12 - 5) x 1 = 7 W
Frequently Asked Questions
When is a linear regulator appropriate?
When input-output voltage difference is small, load current is low, or noise requirements are strict (audio, precision ADCs).
What is dropout voltage?
The minimum V_in - V_out for regulation. Standard regulators need 2V; LDOs need as little as 0.1-0.3V.
LDO vs standard linear regulator?
LDO (Low Dropout) regulators work with smaller input-output differentials, improving efficiency when voltages are close.
Ready to run the numbers?
Open Linear Regulator Efficiency Calculator