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Rojony Khatun Author
Rojony Khatun
CalculatorToolsProjectExpert
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Małgorzata Koperska, MD Steven Wooding
Last updated: October 1, 2025

AC to DC Voltage Calculator | RMS to DC, Rectifier & Ripple

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AC to DC Voltage Calculator

Easily convert AC RMS to DC voltage. Includes half-wave, full-wave, diode drop, and ripple capacitor formulas for accurate rectifier design.

reservoir capacitor ripple calculator

To rectify an AC input To rectify an AC input, use first half-wave average = -2V = full-wave average =2V. Include drops of diodes (single diode ≈V bridge ≈2V with a reservoir capacitor and load I, filtered DC ≈ − V 2FC)-ripple(ripple) =f half-wave, 2f full-wave.

Formula & Table Summary:

  • Half-wave: ΔVpp ≈ I / (f · C)
  • Full-wave: ΔVpp ≈ I / (2 · f · C)
  • DC power & RMS relations: use P = Vdc × Iload (approx for filtered supplies).
  • Converter table — Input → Output

    Input availableUse / FormulaOutput
    Vrms & rectifier typeVp=Vrms√2 → Vdc,avg=Vp/π (half) or 2Vp/π (full)Unfiltered DC average (V)
    Vrms, diode dropsSubtract Vdrops from Vp for practical DCVpeak avail=Vp−Vdrops
    Vrms, I, C, f, rectifier typeΔVpp=I/(fripple·C) → VDCfiltered≈Vp−Vdrops−ΔVpp/2Filtered DC (approx) and ripple
    Desired VDC, I, f, VdChoose C ≈ I / (fripple · ΔVpp,allowed)Required C for target ripple

    rectifier smoothing capacitor calc

    The AC voltage to DC Voltage Calculator is used to transform the voltage between DC and AC circuits (RMS) in rectifier circuits that are filtered or not. It includes peak conversion (Vpeak = Vrms642), average DC of rectified waveforms (half-wave/full-wave), corrections in forward-drop of a single diode (or diode bridge) and single diode (or bridge) smoothed DC using a reservoir capacitor (formulas of approximate ripple). With this tool, design and troubleshooting of power supplies and battery charging circuits are estimated by comparing the unloaded DC (no filter), filtered DC under load, and peak/peak-to-peak ripple.

    rectifier voltage calculator

    ScenarioInputsCalculationResult
    Unfiltered full-wave (ideal)Vrms = 12 V, full-waveVp = 12√2 = 16.971 V; Vdc = 2Vp/π = 2×16.971/πVdc ≈ 10.80 V
    Bridge + smoothing (small ripple)Vrms = 12 V, full-wave bridge (2×Vd), I=0.5 A, f=50 Hz, C=2200 µF, Vd≈0.7 V Vp=16.971 V; Vp_avail=Vp − 2Vd = 16.971 − 1.4 = 15.571 V;
    ΔVpp ≈ I/(2fC) = 0.5/(2×50×2200e-6)=0.5/(0.22)=2.273 V;
    Vdc≈Vp_avail − ΔVpp/2
    Vdc ≈ 15.571 − 1.137 = 14.43 V; ΔVpp ≈ 2.27 V
    Half-wave unfilteredVrms = 9 V, half-waveVp = 9√2 = 12.728 V; Vdc = Vp/π = 12.728/πVdc ≈ 4.05 V
    Required C for small rippleTarget ΔVpp ≤ 0.5 V, I = 1 A, full-wave, f=50 HzC ≥ I / (2f·ΔVpp) = 1 / (2×50×0.5) = 1 / 50 = 0.02 F = 20,000 µFC ≈ 20,000 µF

    Frequently Asked Questions - AC to DC Voltage Calculator:

    How do I convert AC RMS to peak voltage?

    Vpeak = Vrms × √2.

    What is the DC output of a full-wave rectifier (no filter)?

    Vdc_avg = 2×Vpeak / π (use Vpeak = Vrms√2).

    How much voltage drop do diodes cause?

    Silicon diodes ≈0.6–0.8 V each. A bridge uses two drops (≈1.2–1.6 V total).

    How to estimate filtered DC with a reservoir capacitor?

    Approx Vdc ≈ Vpeak − Vdrops − ΔVpp/2 with ΔVpp ≈ I/(f_ripple·C) and f_ripple=2f for full-wave.

    Which ripple formula is correct for full-wave?

    ΔVpp ≈ I / (2·f · C) (ripple frequency is 2f for full-wave rectification).

    How to choose C for allowable ripple?

    C ≥ I / (f_ripple · ΔVpp_allowed). For full-wave, use f_ripple = 2f.

    What is Vdc for half-wave rectifier without filter?

    Vdc_avg = Vpeak / π.

    Can I ignore diode drop for rough estimates?

    Only for very rough estimates at high voltages; for accuracy subtract diode drops from Vpeak.

    How does load current affect DC level?

    Higher load current increases ripple and reduces average DC when filtering is used; it doesn’t change Vpeak but increases ΔVpp.

    Does transformer secondary RMS equal DC after rectification?

    No — RMS is AC measure; DC after rectification depends on peak and rectifier type and filtering.

    Rojony Khatun

    Rojony Khatun

    CalculatorToolsProject

    Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.