Need to know how long one cycle of a 60 Hz signal lasts, or what frequency a 100 ms pulse represents? The relationship is simple but easy to fumble under time pressure: frequency and period are reciprocals. This page gives you an instant converter, the exact formula, a lookup table, and worked examples — so you can move between Hz, kHz, MHz, ms, µs, and ns without second-guessing.
Frequency → Period converter
Formula: period (ms) = 1000 ÷ frequency (Hz). Also shown in µs and seconds.
What Is the Hz to ms Formula?
Hertz (Hz) counts how many cycles happen per second. A period is the time one cycle takes. They are inverses of each other:
- Period in seconds = 1 ÷ frequency (Hz)
- Period in milliseconds (ms) = 1000 ÷ frequency (Hz)
- Frequency (Hz) = 1000 ÷ period (ms)
So 1 Hz is a 1-second period (1000 ms), and 1 ms corresponds to 1000 Hz. If your number is in kHz, MHz, or GHz, convert it to Hz first (multiply by 1,000 / 1,000,000 / 1,000,000,000).
Hz to ms Conversion Table
A quick reference for the frequencies people ask about most:
| Frequency | Period (ms) | Period (µs) | Common context |
|---|---|---|---|
| 1 Hz | 1000 ms | 1,000,000 µs | 1 cycle per second |
| 10 Hz | 100 ms | 100,000 µs | Slow blink / refresh floor |
| 50 Hz | 20 ms | 20,000 µs | Mains power (Europe/Asia) |
| 60 Hz | 16.667 ms | 16,667 µs | Mains power (US) / display refresh |
| 100 Hz | 10 ms | 10,000 µs | Smooth display baseline |
| 120 Hz | 8.333 ms | 8,333 µs | Gaming display refresh |
| 440 Hz | 2.273 ms | 2,273 µs | Concert-pitch A |
| 639 Hz | 1.565 ms | 1,565 µs | Solfeggio tone |
| 1 kHz | 1 ms | 1000 µs | Audio sampling reference |
| 1 MHz | 0.001 ms | 1 µs | Radio / clock lines |
Worked Examples
What is 60 Hz in ms?
1000 ÷ 60 = 16.667 ms. That is why US mains power and 60 Hz displays update one frame every ~16.7 ms — a useful number when reasoning about frame timing and flicker.
What is 100 ns in frequency?
First convert time to seconds: 100 ns = 100 × 10⁻⁹ s = 1 × 10⁻⁷ s. Frequency = 1 ÷ (1 × 10⁻⁷) = 10,000,000 Hz = 10 MHz. This is the conversion to reach for in electronics debugging, where ns- and µs-scale timings are common.
How many Hz is 1 ms?
Using frequency = 1000 ÷ period(ms), 1 ms gives 1000 Hz (1 kHz).
ms to Hz: The Reverse Conversion
Working the other way is the same math rearranged. If you know the period in milliseconds and want the frequency: frequency (Hz) = 1000 ÷ period (ms). For nanoseconds or microseconds, divide by the matching power of ten first (µs → ms: ÷1000; ns → ms: ÷1,000,000) or convert straight to seconds and use 1 ÷ period(s).
Common Mistakes When Converting Hz and ms
- Mixing units. The single biggest error is dividing 1 by a value that is in kHz or ms without converting to base units first. Always convert to Hz and seconds before applying the formula.
- Rounding too early. 60 Hz is 16.6667 ms, not 16.7 ms if you are summing many cycles — the error accumulates. Keep more decimals than you think you need.
- Confusing period with duty cycle. A PWM signal at 1 kHz has a 1 ms period, but the "on" time is the period multiplied by the duty cycle — do not use the period as the pulse width.
- Forgetting that Hz is cycles per second, not per millisecond. If you compute 1/60 expecting milliseconds, you get 0.0167 — which is seconds, or 16.7 ms.
FAQ
How do I convert Hz to ms?
Divide 1000 by the frequency in Hz. Example: 60 Hz → 1000 / 60 = 16.667 ms. Remember that period(ms) = 1000 / frequency(Hz).
What is 1 Hz in ms?
1 Hz = one cycle per second = 1000 ms per cycle.
What is 100 Hz in ms?
1000 ÷ 100 = 10 ms per cycle.
What is 1 ms in Hz?
A 1 ms period equals 1000 Hz (1 kHz).
What is 100 ns in frequency?
100 ns = 1×10⁻⁷ s, so the frequency is 10 MHz.
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