Buck Converter Inductor Calculator

Calculate buck converter inductor value, ripple current, peak switch current, duty cycle, output capacitor ripple and minimum capacitor value for DC-DC step-down converters.

⚡ Maker Rule: The inductor value decides current ripple. Too small can cause high ripple, heat and saturation; too large can make response slow. Use this with the MOSFET Power Loss Calculator, MOSFET Gate Resistor Calculator, Regulator Heat Sink Calculator and PCB Trace Width Calculator.

🌀 Buck Converter — Vin to Vout Through Inductor

Input Voltage Vin

Output Voltage Vout

Output Current

Switching Frequency

Target Ripple Current

Estimated Efficiency

Converter Mode

Typical inductor ripple target is 20–40% of output current. Lower ripple needs a larger inductor.

Presets:12V→5V24V→12V5V→3.3V

Input Voltage Vin

Output Voltage Vout

Inductor Value

Switching Frequency

Output Current

Use this to check ripple current and peak current for an inductor you already selected.

Inductor Ripple Current ΔIL

Switching Frequency

Target Output Ripple

Capacitor ESR Optional

Output ripple has capacitive ripple plus ESR ripple. Low-ESR capacitors are important in switching converters.

📐 Formula Reference

Buck Duty Cycle

D ≈ Vout ÷ Vin

Inductor Value

L = (Vin − Vout) × D ÷ (ΔIL × f)

Peak Inductor Current

Ipeak = Iout + ΔIL ÷ 2

Output Cap Ripple

C ≥ ΔIL ÷ (8 × f × ΔV)

📋 Quick Reference

Ripple Target

Low ripple20%

Typical design30%

Small inductor40%

Inductor Checks

Saturation currentabove peak

RMS currentabove load

DCRlower heat

Design Tips

Higher frequencysmaller L

Lower ripplelarger L

Low ESR capless ripple

📚 Engineering Notes

Inductor saturation is criticalChoose an inductor with saturation current higher than peak inductor current, not only average output current.

Ripple current affects output rippleHigher inductor ripple increases output capacitor ripple current and output voltage ripple.

MOSFET losses matterUse the MOSFET Power Loss Calculator to estimate switching and conduction heat.

Layout is importantKeep high-current switching loops short. Check PCB current paths with the PCB Trace Width Calculator.

What is a Buck Converter Inductor Calculator?

A buck converter inductor calculator helps choose the inductor value for a step-down DC-DC converter. It estimates duty cycle, ripple current, peak inductor current and output capacitor requirements.

How buck converter inductor value is calculated

The calculator uses input voltage, output voltage, switching frequency and target ripple current. A common design target is 20–40% ripple current compared with output current.

Choosing a buck converter inductor

After calculating inductance, choose a real inductor with suitable saturation current, RMS current rating, low DCR, acceptable size, frequency rating and temperature rise.

Important limitation

This calculator gives first-order continuous-conduction buck converter estimates. Real designs should follow the controller IC datasheet and check compensation, transient response, diode/MOSFET losses, layout, EMI, capacitor ESR and thermal performance.

❓ Frequently Asked Questions

A common starting point is 20–40% of output current. 30% is often used for practical first estimates.

Ripple current increases, peak current rises, output ripple can increase and the inductor may saturate or run hot.

The saturation current should be above the peak inductor current, and RMS current rating should be above the expected load current with margin.