Boost Converter Calculator — DC-DC Step-Up Design
Enter the input voltage, desired output voltage, load current and converter efficiency to instantly get the duty cycle, input current, output power and power losses for a boost (step-up) switching converter.
V
V
A
%
Fraction of each switching cycle that the transistor is ON
- 1
Voltage ratio V_in ÷ V_out
5 ÷ 12 = 0.4167 - 2
Duty cycle D = 1 − V_in ÷ V_out
1 − 0.4167 = 58.33D as a percentage: fraction of each switching cycle the transistor is ON.
How does this calculator work?
A boost converter steps up DC voltage using D = 1 − V_in/V_out. Input current I_in = P_out / (V_in × η). Enter V_in, V_out, load current and efficiency to get the duty cycle (how long the switch stays ON each cycle), input current, output power and heat dissipation.
Formula
How this is calculated
A boost converter is a switching power supply that raises a DC voltage above its input level. A transistor (switch) turns on and off at a high frequency; when on, energy is stored in an inductor, and when off, that energy is released to the output capacitor at a higher voltage. The ratio of on-time to the full switching period is called the duty cycle D. In an ideal converter, D = 1 − V_in / V_out — a higher D means a bigger voltage step-up, but also more stress on the switching components.
Real converters are not 100 % efficient: MOSFET switching losses, inductor winding resistance, diode drops and capacitor ESR all waste some power as heat. This calculator accounts for that with an efficiency parameter (η). The input power is P_out / η and the input current is P_in / V_in. Power loss is simply P_in − P_out, which tells you how much heat the circuit must dissipate.
The formulas here cover steady-state operation at a fixed load. They do not compute inductor ripple current, output voltage ripple, or component ratings — those require the switching frequency and component values. Use the results here as a starting point for selecting power ratings and efficiency targets before moving to a full simulation or datasheet calculation.
Frequently asked questions
The duty cycle D is the fraction of each switching cycle during which the transistor switch is closed (on). D = 1 − V_in / V_out in an ideal converter. For example, stepping 5 V up to 12 V requires D = 1 − 5/12 ≈ 58.3%. Higher duty cycles mean larger voltage step-ups but also more thermal and current stress on components.
Power is conserved (minus losses): P_in ≈ P_out. Since V_in < V_out, the current must be proportionally higher at the input than at the output. This is why wiring and fuses on the input side of a boost converter must handle more current than those on the output side.
Well-designed boost converters typically achieve 80–95 % efficiency, depending on the switching frequency, MOSFET and diode quality, inductor losses and load current. ICs from major manufacturers often specify peak efficiency at a particular load — check the datasheet and derate somewhat for worst-case thermal design.
TG we-Calculate Editorial Team. (2026). Boost Converter Calculator — DC-DC Step-Up Design [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/boost-converter
TG we-Calculate Editorial Team. "Boost Converter Calculator — DC-DC Step-Up Design." TG we-Calculate. 2026. https://we-calculate.com/calculator/boost-converter.
TG we-Calculate Editorial Team, "Boost Converter Calculator — DC-DC Step-Up Design," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/boost-converter
@misc{wecalculate_boost_converter, title = {Boost Converter Calculator — DC-DC Step-Up Design}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/boost-converter}}, year = {2026}, note = {TG we-Calculate} }
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