user3464: Short and simple: What is the power consumption for an ATtiny85 running at 1 MHz and 8 MHz using the internal clock? Not using any sleep modes.
I have googled a lot and can't find any info on this. I ask because I want to know if it is worth using 1 MHz to increase battery life.

user10794: The datasheet shows that current decreases at lower frequencies. Around 1 mA at 1 MHz running at 5 V. More like 5 mA at 8 MHz running at 5 V.

You can save quite a bit by using lower voltages as well, as you can see. For really big savings use a sleep mode. Read about Power saving techniques for microprocessors.

(Edited to add)
To amplify on my remarks, you should be able to get 200 nA consumption at 3.5 V in sleep mode with no watchdog timer. That will still respond to interrupts, such as closing a switch. 


If you need to do things periodically you can enable the watchdog, and then get around 5 µA consumption at 3.5 V.


This is so much less current than the 1 mA mentioned above, that it is well worth exploring running in power-down mode, where possible.

3464: <p>Short and simple: What is the power consumption for an ATtiny85 running at 1 MHz and 8 MHz using the internal clock? Not using any sleep modes.</p>

<p>I have googled a lot and can't find any info on this. I ask because I want to know if it is worth using 1 MHz to increase battery life.</p>
 10794: <p>The datasheet shows that current decreases at lower frequencies. Around <strong>1 mA</strong> at 1 MHz running at 5 V. More like 5 mA at 8 MHz running at 5 V.</p>

<p><a href="https://i.stack.imgur.com/sJkkV.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sJkkV.png" alt="Supply current vs frequency"></a></p>

<p>You can save quite a bit by using lower voltages as well, as you can see. For really big savings use a sleep mode. Read about <a href="http://www.gammon.com.au/power" rel="noreferrer">Power saving techniques for microprocessors</a>.</p>

<hr>

<p><em>(Edited to add)</em></p>

<p>To amplify on my remarks, you should be able to get <strong>200 nA</strong> consumption at 3.5 V in sleep mode with no watchdog timer. That will still respond to interrupts, such as closing a switch. </p>

<p><a href="https://i.stack.imgur.com/oagxo.png" rel="noreferrer"><img src="https://i.stack.imgur.com/oagxo.png" alt="Supply current with watchdog disabled"></a></p>

<hr>

<p>If you need to do things periodically you can enable the watchdog, and then get around <strong>5 µA</strong> consumption at 3.5 V.</p>

<p><a href="https://i.stack.imgur.com/ZPVOo.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ZPVOo.png" alt="Supply current with watchdog enabled"></a></p>

<hr>

<p>This is so much less current than the 1 mA mentioned above, that it is well worth exploring running in power-down mode, where possible.</p>
