Boost Converter Calculator

What Is a Boost Converter?

A boost converter is a DC-to-DC switched-mode power supply that steps up input voltage to a higher output voltage. It uses an inductor, switch, diode, and output capacitor to store energy during the on-time and release it during the off-time.

Boost Converter Formulas

$$V_{out} = \frac{V_{in}}{1 - D}$$

$D$ is the duty cycle (fraction of the switching period the switch is on). Equivalently:

$$D = 1 - \frac{V_{in}}{V_{out}}$$

Example: stepping 5.5 V up to 12 V gives $D = 1 - 5.5/12 = 54.17\%$. Average inductor current equals input current: $I_{L,avg} = P / V_{in}$ when load power is known.

Inductor Average Current

For an ideal converter, input power equals output power. With load power $P$ and output voltage $V_{out}$:

$$I_{out} = \frac{P}{V_{out}}, \quad I_{L,avg} = \frac{P}{V_{in}} = I_{out} \cdot \frac{V_{out}}{V_{in}}$$

If you know load current instead, multiply by the voltage ratio to get inductor average current.

Frequently Asked Questions

When do I use a boost converter?

Use a boost converter when the output voltage must be higher than the input, such as stepping a single Li-ion cell (3.7 V) up to 5 V or 12 V for LEDs and sensors.

What duty cycle should I target?

Moderate duty cycles (roughly 40–70%) balance efficiency and boost ratio. Very high duty cycles increase conduction and inductor losses.

How is boost different from buck?

A buck converter steps voltage down ($V_{out} < V_{in}$). A boost converter steps voltage up ($V_{out} > V_{in}$).

Why does inductor current matter?

The inductor must carry the average input current without saturating. Size the inductor and switch for $I_{L,avg}$ plus ripple current.

Can output voltage be less than input?

No. A standard boost topology only produces $V_{out} > V_{in}$. Use a buck or buck-boost topology to step down.

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Boost Converter Calculator

What Is a Boost Converter?

Boost Converter Formulas

Inductor Average Current

Frequently Asked Questions

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