Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Electronics & Hardware Engineering
RC Time Constant Calculator — Capacitor Charging Time
τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
Compute RC time constant and capacitor charge times. Planning estimates only — verify with production tools and vendor pricing where applicable.
Inputs
110000000
0.00110000
Smart analysis
Recommendations
Tailored to your live inputs and result—guidance only, not professional advice.
- Interpret
Treat this as a planning estimate
Primary result: Time constant τ = 1.00 sec. Re-run with optimistic and pessimistic inputs to understand the range—not just a single point.
Scenario studio
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Scenario A
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Scenario B
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Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Resistance (Ω)
The “Resistance (Ω)” value used in this tool’s formula. Adjust it to see results update live.
Capacitance (µF)
The “Capacitance (µF)” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Compute RC time constant and capacitor charge times. Planning estimates only — verify with production tools and vendor pricing where applicable. τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ. Example: 10 kΩ × 100 µF → τ = 1 s; 95% charge in ~3 seconds.
τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
Example: 10 kΩ × 100 µF → τ = 1 s; 95% charge in ~3 seconds.
When to use this Capacitor RC Time Constant
Common use cases
- Compute RC time constant and capacitor charge times.
- Sanity-check with this case: 10 kΩ × 100 µF → τ = 1 s; 95% charge in ~3 seconds.
- The relationship is: τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
Localized examples
- Electronics & Hardware Engineering: the example on this page uses the same formula as the widget.
What you get
- Fields: Resistance (Ω), Capacitance (µF)
- τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
- Example on the page: 10 kΩ × 100 µF → τ = 1 s; 95% charge in ~3 seconds.
How to Calculate Capacitor RC Time Constant Step-by-Step
- 1Enter Resistance (Ω), Capacitance (µF). Use the values you have, not a catalog average, unless that is all you know.
- 2τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
- 3Worked case: 10 kΩ × 100 µF → τ = 1 s; 95% charge in ~3 seconds.
- 4Compare the result to last month’s invoice or a vendor calculator before you commit capacity.
Governing formula
τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
10 kΩ × 100 µF → τ = 1 s; 95% charge in ~3 seconds.
Example: set Resistance (Ω) = 10,000, Capacitance (µF) = 100, then read the result.
Variable definitions
- resistance
Resistance (Ω)
The “Resistance (Ω)” field. Default 10000; typical range 1–10000000.
- capacitanceUf
Capacitance (µF)
The “Capacitance (µF)” field. Default 100; typical range 0.001–10000.
- Closed-form math (τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.) misses idle time, egress, packet loss, and reserved capacity on the real bill.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
τ = R × C; 63% charge = τ; 95% ≈ 3τ; 99% ≈ 5τ.
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Community
Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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