555 Timer Calculator
Calculate classic 555 astable frequency, high/low times and duty cycle, or a monostable pulse width, with selectable component units.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use the classic bipolar 555 datasheet approximations. Astable mode separates capacitor charge and discharge intervals; monostable mode uses one RC pulse constant.
Astable: tH≈0.693(R1+R2)C, tL≈0.693R2C, f=1/(tH+tL); monostable: t≈1.1RC
Worked example
With R1=10 kΩ, R2=47 kΩ and C=10 µF, the astable period is about 0.7207 s and frequency about 1.3875 Hz.
Assumptions and input details
Nominal first-order formulas for the classic 555 topology. Actual thresholds, leakage, minimum resistance, maximum frequency, supply voltage, output loading and component tolerances depend on the device and circuit. A standard two-resistor astable has a high-duty fraction above 50%. Check the exact device datasheet before construction.
References: Texas Instruments NE555 datasheet
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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