<p>I did a little bit of digging. Block <strong>1597133</strong>, created on <strong>2020/07/28 20:20:16</strong> was the first block to use 1 second per slot.</p>
<div class="s-table-container">
<table class="s-table">
<thead>
<tr>
<th style="text-align: right;">Epoch</th>
<th style="text-align: right;">Slot</th>
<th style="text-align: right;">Block</th>
<th style="text-align: right;">Created</th>
<th style="text-align: right;">Delta Next Slot</th>
<th style="text-align: right;">Delta Next Created</th>
<th style="text-align: right;">Time Per Slot</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: right;">73</td>
<td style="text-align: right;">1598398</td>
<td style="text-align: right;">1597131</td>
<td style="text-align: right;">2020/07/28 20:19:36</td>
<td style="text-align: right;">1</td>
<td style="text-align: right;">00:00:20</td>
<td style="text-align: right;">00:00:20</td>
</tr>
<tr>
<td style="text-align: right;">73</td>
<td style="text-align: right;">1598399</td>
<td style="text-align: right;">1597132</td>
<td style="text-align: right;">2020/07/28 20:19:56</td>
<td style="text-align: right;">1</td>
<td style="text-align: right;">00:00:20</td>
<td style="text-align: right;">00:00:20</td>
</tr>
<tr>
<td style="text-align: right;">74</td>
<td style="text-align: right;">1598400</td>
<td style="text-align: right;"><strong>1597133</strong></td>
<td style="text-align: right;">2020/07/28 20:20:16</td>
<td style="text-align: right;">20</td>
<td style="text-align: right;">00:00:20</td>
<td style="text-align: right;"><strong>00:00:01</strong></td>
</tr>
<tr>
<td style="text-align: right;">74</td>
<td style="text-align: right;">1598420</td>
<td style="text-align: right;">1597134</td>
<td style="text-align: right;">2020/07/28 20:20:36</td>
<td style="text-align: right;">20</td>
<td style="text-align: right;">00:00:20</td>
<td style="text-align: right;">00:00:01</td>
</tr>
<tr>
<td style="text-align: right;">74</td>
<td style="text-align: right;">1598440</td>
<td style="text-align: right;">1597135</td>
<td style="text-align: right;">2020/07/28 20:20:56</td>
<td style="text-align: right;"></td>
<td style="text-align: right;"></td>
<td style="text-align: right;"></td>
</tr>
</tbody>
</table>
</div>
<ul>
<li><strong>Delta Previous Slot</strong> is the difference between the block's slot and the one before it</li>
<li><strong>Delta Previous Created</strong> is the difference between the blocks creation date and the one before it</li>
<li><strong>Time Per Slot</strong> is <strong>Delta Previous Created</strong> divided by <strong>Delta Previous Slot</strong></li>
</ul>
<p><a href="https://explorer.cardano-testnet.iohkdev.io/en/browse-blocks.html?page=79857&amp;perPage=20" rel="nofollow noreferrer">Page on Cardano Testnet Blockchain Explorer with these blocks</a></p>

CC BY-SA 4.0
2022-02-01T19:24:35.203Z
great! Thanks a lot!
kindofdev
CC BY-SA 4.0
2022-02-03T00:00:19.450Z
From the info in the table I'd say that the first block with 1 sec would be 1597133 because the difference in slots with the next one (1597134) is 20 slots.
kindofdev
CC BY-SA 4.0
2022-02-04T03:57:00.800Z
You're right. I've updated my answer
Travis
CC BY-SA 4.0
2022-02-01T18:08:55.910Z
2022-02-04T03:56:39.657Z
2022-02-04T03:56:39.657Z
Travis
<p>I'd like to know the exact date when the slot duration was set to 1 sec on Cardano Testnet.</p>
<p>Thanks in advance!</p>

<cardano-node><testnet><slottime>
When was the slot duration set to 1 sec on Cardano Testnet?
# When was the slot duration set to 1 sec on Cardano Testnet?

(Asked by: username_0 on 2022-01-30)

I'd like to know the exact date when the slot duration was set to 1 sec on Cardano Testnet.

Thanks in advance!

**Tags:** cardano-node, testnet, slottime

---

## 1 answers

### Answer by username_1 on 2022-02-01. Score: 4 | Accepted answer

I did a little bit of digging. Block **1597133**, created on **2020/07/28 20:20:16** was the first block to use 1 second per slot.

| Epoch | Slot | Block | Created | Delta Next Slot | Delta Next Created | Time Per Slot |
| --- | --- | --- | --- | --- | --- | --- |
| 73 | 1598398 | 1597131 | 2020/07/28 20:19:36 | 1 | 00:00:20 | 00:00:20 |
| 73 | 1598399 | 1597132 | 2020/07/28 20:19:56 | 1 | 00:00:20 | 00:00:20 |
| 74 | 1598400 | **1597133** | 2020/07/28 20:20:16 | 20 | 00:00:20 | **00:00:01** |
| 74 | 1598420 | 1597134 | 2020/07/28 20:20:36 | 20 | 00:00:20 | 00:00:01 |
| 74 | 1598440 | 1597135 | 2020/07/28 20:20:56 |  |  |  |

* **Delta Previous Slot** is the difference between the block's slot and the one before it
* **Delta Previous Created** is the difference between the blocks creation date and the one before it
* **Time Per Slot** is **Delta Previous Created** divided by **Delta Previous Slot**

[Page on Cardano Testnet Blockchain Explorer with these blocks](https://explorer.cardano-testnet.iohkdev.io/en/browse-blocks.html?page=79857&perPage=20)

> **Comments:**
> **username_0**: great! Thanks a lot!  
> **username_0**: From the info in the table I'd say that the first block with 1 sec would be 1597133 because the difference in slots with the next one (1597134) is 20 slots.  
> **username_1**: You're right. I've updated my answer  

---

