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Buck Converter Calculator — Duty Cycle, Input Current & Ideal Power
Estimate ideal buck-converter duty cycle, output power, input current and conversion loss from input/output voltage, output current and efficiency.
Last updated: September 16, 2026
Results
Ideal duty cycle 41.66667%
Output power 10 W
Estimated input current 0.9259259 A
Estimated loss 1.111111 W
Formula, example and assumptions
D≈Vout/Vin; Pout=Vout·Iout; Pin≈Pout/η; Iin≈Pin/Vin.
12 V to 5 V gives an ideal duty cycle of about 41.7%.
- Continuous-conduction ideal duty-cycle model.
- Switch loss, diode drop, ripple, minimum on-time and control topology require datasheet checks.
Frequently asked questions
Why is duty cycle Vout divided by Vin?
For an ideal continuous-conduction buck, the inductor volt-seconds balance to Vout≈D·Vin.
Can duty cycle exceed 100%?
No. A buck cannot ideally produce output above input; use a boost or buck-boost topology.