Boost Converter Calculator
A boost converter is a switching power supply that produces an output voltage higher than its input, used in battery-powered devices, LED drivers, and photovoltaic systems. Its behaviour in continuous conduction mode is governed by a single duty cycle that sets the step-up ratio. Enter the input voltage, the desired output voltage, the output current, and the converter efficiency; this calculator returns the required duty cycle, the output power, the ideal and real input current, and the input power drawn from the source.
Boost converter formula
Duty cycle = 1 - Vin / Vout
Output power = Vout * Iout
Input power = output power / efficiency
Input current = input power / Vin
Efficiency is entered as a percentage and divided by 100 in the calculation. The duty cycle is valid for continuous conduction mode where the output exceeds the input.
Switching converter context
- A boost converter always steps voltage up; the output voltage exceeds the input voltage.
- The duty cycle is the fraction of each switching period the main switch is on.
- Higher step-up ratios need duty cycles close to one, which increases stress and lowers efficiency.
- Input current exceeds output current because power is conserved while voltage is raised.
- Real efficiency depends on the switch, diode, inductor, and capacitor losses at your operating point.
Boost converter: frequently asked questions
How do I find a boost converter's duty cycle?
For an ideal continuous-conduction boost converter the duty cycle D satisfies Vout = Vin / (1 - D), so D = 1 - Vin / Vout. The output voltage is always higher than the input, which is why it is called a step-up converter.
Why is the input current higher than the output current?
A boost converter raises voltage, so to conserve power it must draw more current at the input than it delivers at the output. Ignoring losses, input power equals output power, so the input current is the output power divided by the input voltage.
How does efficiency affect the calculation?
Real converters lose some power in the switch, diode, inductor, and capacitor. Input power equals output power divided by efficiency. This calculator uses your entered efficiency to compute the real input current, which is higher than the ideal value.
What is continuous conduction mode?
Continuous conduction mode means the inductor current never falls to zero during a switching cycle. The simple duty-cycle relationship D = 1 - Vin / Vout assumes this mode. At light loads a converter may enter discontinuous mode, where the relationship changes.
Can a boost converter step voltage down?
No. A boost converter only steps voltage up; its output is always greater than its input. To step voltage down you use a buck converter, and to do either you use a buck-boost or other topology.
Official sources
- NIST: SI electrical units, the volt, ampere and watt (SP 811).
- U.S. Department of Energy: Federal Energy Management Program (power conversion efficiency).
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.