Boost Converter Calculator
Calculate boost converter duty cycle, inductor value, capacitor value, ripple current and current stress for DC-DC step-up power supply circuits.
β‘ Design Rule: A boost converter can step voltage up, but output current is always limited by input power, efficiency, inductor current and switch/diode ratings. Use this with the Buck Converter Inductor Calculator, MOSFET Power Loss Calculator, MOSFET Gate Resistor Calculator and Voltage Regulator Heat Sink Calculator.
π Boost Converter: Vin β Inductor + Switch β Diode + Capacitor β Higher Vout
Input Voltage Vin
Output Voltage Vout
Output Current
Efficiency
Switching Frequency
Inductor Ripple
Output Ripple
Diode Drop Optional
This tab gives a practical boost converter starting point: duty cycle, input current, inductor, capacitor and current/voltage stress.
Presets:
Vin
Vout
Load Current
Switching Frequency
Inductor Ripple Current
Output Ripple Voltage
Use this tab when you already know the allowed inductor ripple current and output voltage ripple.
Ripple presets:
Input Voltage Vin
Duty Cycle
Output Current
Efficiency
Switching Frequency
Inductor Value Optional
This tab estimates output voltage from duty cycle. Real voltage will be lower due to losses and may be limited by controller maximum duty cycle.
Duty presets:
π Formula Reference
Ideal Duty Cycle
D = 1 - Vin / Vout
Ideal Boost Output
Vout = Vin / (1 - D)
Inductor Estimate
L = Vin Γ D / (ΞIL Γ fs)
Output Capacitor
C = Iout Γ D / (fs Γ ΞVout)
π Quick Reference
Typical Duty Range
Low boost10β35%
Medium boost35β65%
High stress>75%
Ripple Choice
Low ripple20%
Typical30β40%
Compact40β60%
Component Stress
MOSFET Vds> Vout
Diode reverse> Vout
Inductor currentIavg + ripple
π Design Notes
Input current is higher than output currentA boost converter raises voltage by drawing more current from the input. Always check input supply, inductor saturation current and switch peak current.
High duty cycle is stressfulAbove about 75β80% duty cycle, current stress, diode loss, MOSFET loss and control limits become more serious.
Inductor saturation mattersChoose an inductor with saturation current above calculated peak current, not just above average current.
Use real IC datasheetsThis calculator is a design starting point. Final values should be checked with the converter IC datasheet, layout guide and thermal testing.
What is a Boost Converter Calculator?
A boost converter calculator helps design a DC-DC step-up converter. It estimates duty cycle, output voltage, input current, inductor value, capacitor value, ripple current and component stress from the selected voltage, current and frequency.
How to calculate boost converter duty cycle
For an ideal boost converter, duty cycle is calculated as D = 1 - Vin / Vout. Real designs need extra margin because diode drop, MOSFET resistance, inductor resistance, switching loss and controller limits reduce actual performance.
How to calculate boost converter inductor value
The common continuous-conduction-mode estimate is L = Vin Γ D / (ΞIL Γ fs). Ripple current is often selected as a percentage of average inductor/input current.
Why does a boost converter output voltage drop under load?
Output voltage can drop because the input supply cannot provide enough current, the inductor saturates, the switch current limit is reached, diode/MOSFET losses are high, PCB layout is poor, or the selected duty cycle is too close to the controller limit.
β Frequently Asked Questions
Use D = 1 - Vin / Vout for an ideal boost converter. Example: 5V to 12V gives D = 1 - 5/12 = 58.3%. Real designs need loss margin.
Use L = Vin Γ D / (ΞIL Γ fs). Choose ΞIL based on allowed ripple current. Many practical designs start around 20β40% of average inductor current.
A basic estimate is C = Iout Γ D / (fs Γ ΞVout). Also check capacitor ESR, ripple current rating, voltage rating and transient response.
No. It increases voltage by drawing higher input current. Output power is always lower than input power because efficiency is less than 100%.
No. A basic boost converter only steps voltage up. Use a buck converter for step-down or a buck-boost converter when the input can be above or below the output.
High duty cycle increases inductor current, switch stress, diode stress and losses. Many controllers also have maximum duty limits, so the converter may fail to regulate.
The MOSFET drain-source voltage should be rated above the output voltage plus spikes. Use a safe margin and consider snubber/clamp design for switching transients.
The diode reverse voltage should be higher than the output voltage, and current rating should handle output and ripple current. Schottky diodes are common at lower voltages, while synchronous rectification is used for higher efficiency.