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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Bit time</span></span>
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</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="Slot_time" title="Slot time">Slot time</a></div>
<p>
<b>Bit time</b> is a concept in <a href="Computer_network" title="Computer network">computer networking</a>.<sup id="cite_ref-x113_1-0" class="reference"><a href="#cite_note-x113-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> It is defined as the time it takes for one bit to be ejected from a <a href="Network_interface_controller" title="Network interface controller">network interface controller</a> (NIC) operating at some predefined standard speed, such as 10 Mbit/s.<sup id="cite_ref-h822_2-0" class="reference"><a href="#cite_note-h822-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The time is measured between the time the <a href="Logical_link_control" title="Logical link control">logical link control</a> sublayer receives the instruction from the <a href="Operating_system" title="Operating system">operating system</a> until the bit actually leaves the NIC. The bit time has nothing to do with the time it takes for a bit to travel on the network medium but has to do with the internals of the NIC. Typically this refers to the smallest usable reference time, often also referred to as the 'minimum time quantum'.<sup id="cite_ref-y207_3-0" class="reference"><a href="#cite_note-y207-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-m371_4-0" class="reference"><a href="#cite_note-m371-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>
</p><p>To calculate the bit time at which a NIC ejects bits, use the following:
</p>
<pre> bit time = 1 / NIC speed
</pre>
<p>To calculate the bit time for a 10 Mbit/s NIC, use the formula as follows:
</p>
<pre> bit time = 1 / (10 * 10^6)
= 10^-7
= 100 * 10^-9
= 100 nanoseconds
</pre>
<p>The bit time for a 10 Mbit/s NIC is 100 nanoseconds. That is, a 10 Mbit/s NIC can eject 1 bit every 0.1 microsecond (100 nanoseconds = 0.1 microseconds).
</p><p>Bit time is distinctively different from <a href="Slot_time" title="Slot time">slot time</a>, which is the time taken for a pulse to travel through the longest permitted length of network medium.
</p>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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<li id="cite_note-x113-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-x113_1-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
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</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.pcmag.com/encyclopedia/term/bit-time">"Definition of bit time"</a>. <i>PCMAG</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2025-06-23</span></span>.</cite></span>
</li>
<li id="cite_note-h822-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-h822_2-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFDyeMcDonaldRufi2007" class="citation book cs1">Dye, Mark; McDonald, Richard; Rufi, Antoon (2007-10-29). <i>Network Fundamentals, CCNA Exploration Companion Guide</i>. Cisco Press. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-13-287743-5</bdi>.</cite></span>
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<li id="cite_note-y207-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-y207_3-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFParet2007" class="citation book cs1">Paret, Dominique (2007-06-13). <i>Multiplexed Networks for Embedded Systems</i>. John Wiley & Sons. p. 90. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-470-51170-1</bdi>.</cite></span>
</li>
<li id="cite_note-m371-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-m371_4-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFNataleZengGiustoGhosal2012" class="citation book cs1">Natale, Marco Di; Zeng, Haibo; Giusto, Paolo; Ghosal, Arkadeb (2012-01-19). <i>Understanding and Using the Controller Area Network Communication Protocol</i>. Springer Science & Business Media. p. 5. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-4614-0314-2</bdi>.</cite></span>
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