mAs to mAh conversion
May I know how to convert mAs to mAh?
I have a chip operating at 3.3 V.
Its standby current is 0.00085 mA.
In one day, the chip is active for only 4.24 s.
To calculate the standby energy consumption, my calculation is as follows:
(0.00085 mA) × (86400 − 4.24) s = 73.44 mAs
To convert this to mAh, I used the following calculation:
(73.44 mAs) ÷ (3600 s/h) = 0.020 mAh
Is my calculation correct?
Do I need to consider the operating voltage of the chip?
1 answer
The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| newbie | (no comment) | Oct 9, 2025 at 11:33 |
The best way to not mess up conversions like this is to write out the units for everything carefully. Of course you should do that anyway.
Your current is apparently 0.00085 mA. Or more properly in grown-up units, that's 850 nA. The system is in standby mode all but 4.24 seconds per day. The daily standby current consumption is therefore:
(850 nA)[(60 s/minute)(60 minutes/hour)(24 hour/day)(1 day) - 4.24 s]
= (850 nA)[(86400 s/day)(1 day) - 4.24 s)
= (850 nA)(86,396 s)
= 73,436,600 nAs = 73.4 mAs
To convert that to mAh, just do the math:
(73.4 mAs)/(3600 s/hour)
= 0.020 mAh
Or in proper engineering units:
= 20 µAh
This is a great example of how not being sloppy makes the answer obvious.
Write values with proper units!
Do I need to consider the operating voltage of the Chip?
Not if all you want to know is current consumption. If you wanted to know power consumption, then you'd have to multiply by the voltage that current is delivered at.
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