# Capacitor Series / Parallel / Reactance Calculator Combine capacitors in series/parallel, compute reactance Xc and RC time constant, with schematics and a reactance curve > Canonical page: https://elysiatools.com/en/tools/capacitor-calculator - **Category:** Math & Numbers - **Keywords:** capacitor, capacitance, series, parallel, reactance, xc, rc time constant, electronics, circuit, farad ## Overview Combine capacitors and analyze their AC behavior. Modes: - Series: 1/C = 1/C1 + 1/C2 + … → total decreases; voltage divides inversely to capacitance. - Parallel: C = C1 + C2 + … → total increases. - Reactance: Xc = 1 / (2πfC) for a single capacitor. Optional series resistor R gives the RC time constant τ = R·C (63.2% charge in one τ). Value suffixes: p, n, u/µ, m. e.g. "100n" = 100 nF. ## Inputs - **Calculation Mode** (select) - **Capacitance Values (one per line, or comma-separated)** (textarea): e.g. 100n 220n 470n (used in series/parallel mode) - **Single Capacitor Value (F)** (number): reactance mode only, e.g. 0.000001 (1 µF) — or use suffix below - **Frequency (Hz, for reactance)** (number): e.g. 1000 — needed for reactance mode, optional elsewhere - **Series Resistor R (Ω, for RC time constant)** (number): e.g. 10000 — optional, enables τ = R·C ## When to use - When designing filter circuits or power supply decoupling networks and you need to find the total equivalent capacitance of multiple capacitors. - When calculating the AC impedance (capacitive reactance) of a capacitor at a specific operating frequency. - When determining the charge/discharge timing behavior (RC time constant) of a resistor-capacitor network. ## How it works - Select the calculation mode: Series, Parallel, or Reactance. - Input the capacitance values using standard unit suffixes like p, n, u, or m (e.g., 100n for 100 nF) for series/parallel, or enter a single capacitor value and frequency for reactance. - Optionally enter a series resistor value in ohms to calculate the RC time constant (τ = R·C). - View the calculated equivalent capacitance, reactance, or time constant alongside the generated schematic and reactance curve. ## Use cases - Combining non-standard capacitor values in parallel to achieve a specific target capacitance for a prototype circuit. - Calculating the impedance of a coupling capacitor in an audio amplifier circuit at a specific frequency. - Designing a simple hardware debounce circuit for a microcontroller input pin by calculating the RC time constant. ## Frequently asked questions ### What unit suffixes does the calculator support? You can use p (picofarads), n (nanofarads), u or µ (microfarads), and m (millifarads) to quickly input values. ### How is the RC time constant calculated? It is calculated as τ = R·C, representing the time required to charge the capacitor to approximately 63.2% of its full value through the series resistor. ### What formula is used for capacitive reactance? The calculator uses Xc = 1 / (2πfC), where f is the frequency in Hertz and C is the capacitance in Farads. ### Can I mix different unit suffixes in the series/parallel input? Yes, the calculator automatically parses and normalizes mixed units like 100n, 2.2u, and 470p. ### Why does equivalent capacitance decrease in series? In series, the reciprocal of the total capacitance is the sum of the reciprocals of the individual capacitances, which divides the voltage across them. ## Related tools - [LED Series Resistor Calculator](https://elysiatools.com/en/tools/led-resistor-calculator): Compute the current-limiting resistor for LEDs in series with power, nearest standard value and wattage rating - [Resistor Series / Parallel Calculator](https://elysiatools.com/en/tools/resistor-series-parallel-calculator): Combine resistors in series, parallel, or an arbitrary +/| expression, with per-resistor voltage and power - [Voltage Divider Calculator](https://elysiatools.com/en/tools/voltage-divider-calculator): Calculate divider output voltage, solve for R1 or R2, and evaluate load effects with a circuit diagram - [Active Earth Pressure (Rankine)](https://elysiatools.com/en/tools/active-earth-pressure): Calculate the Rankine active earth pressure on a smooth vertical wall backfilled with cohesionless soil. K_a = tan²(45°−φ/2). Optional uniform surcharge q. Returns the base pressure p₀, the total force P, and the resultant height. - [RLC Admittance Calculator (Y = G + jB)](https://elysiatools.com/en/tools/admittance-calculator): Compute complex admittance Y = 1/Z = G + jB for series or parallel RLC circuits: G = R/|Z|², B = −X/|Z|². Returns conductance, susceptance, magnitude and phase angle. Supports any subset of R/L/C. - [Bearing Capacity Calculator (Terzaghi)](https://elysiatools.com/en/tools/bearing-capacity-calculator): Calculate the Terzaghi ultimate bearing capacity of a shallow foundation: q_ult = c·Nc·sc + q·Nq·sq + 0.5·γ·B·Nγ·sγ. Computes Nc/Nq/Nγ and shape factors automatically; supports strip, square, and circular footings. Result in kPa. - [Bending Stress Calculator](https://elysiatools.com/en/tools/bending-stress-calculator): Calculate the maximum bending (flexural) stress σ_max = M·c/I = M/Z at the outermost fiber of a beam section. Supports solid circle, rectangle, hollow tube, and I-beam; computes I, section modulus Z, and distance c automatically. Stress in MPa. - [Break-Even Calculator](https://elysiatools.com/en/tools/break-even-calculator): Calculate the break-even point for a product or business based on fixed costs, variable costs, and price ## Samples - [Capacitor Hybrid App Development Samples](https://elysiatools.com/en/samples/capacitor-samples): Capacitor hybrid app development examples including native device APIs, plugins, cross-platform deployment, and Progressive Web App capabilities - [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion - [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion - [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion ## Related content - [Electrical Circuit Calculation, Power, and Cable Sizing Tools](https://elysiatools.com/en/hubs/electrical-circuit-power-and-cable-sizing): Compare Ohm's law, resistor and capacitor network math, voltage divider and cable drop calculators, electricity cost tools, and power or energy converters in one focused electrical hub.