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Boost Converter Duty Cycle Calculator

Work out boost converter duty cycle instantly with clear inputs, formula shown and shareable results.

About Boost Converter Duty Cycle Calculator

A boost converter has duty cycle D = 1 - Vin/Vout, so the higher the step-up ratio the closer duty approaches one. Input current is output power divided by input voltage and efficiency, which is why a low-voltage boost draws far more current than its output rating suggests.

Formula

Boost converter

D = 1 - Vin/Vout; Iin = Vout x Iout / (Vin x efficiency)

Worked example

With the default values below, Boost Converter Duty Cycle Calculator returns Duty cycle of 69.167%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Input voltage
3.7 V
Output voltage
12 V
Output current
0.5 A
Efficiency
88 %

Results

Duty cycle
69.167% %
Average input current
1.8428 A
Voltage conversion ratio
3.24 x
Peak switch current estimate
2.3956 A

Step by step

  1. 1Values used
  2. 2Boost converter
  3. 3Duty cycle= 69.167 %
  4. 4Average input current= 1.8428 A
  5. 5Voltage conversion ratio= 3.24 x
  6. 6Peak switch current estimate= 2.3956 A

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Why do very high step-up ratios fail?

Duty cycle approaches 100%, leaving no time to transfer energy, while conduction losses rise sharply. Beyond about 5:1 a transformer-based topology is better.

Why does the input current matter so much?

Stepping 3.7 V up to 12 V at 0.5 A needs over 1.8 A in, so the battery, inductor and switch must all be rated for the input current, not the output.

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