Low OG

[eyalius]

By mistake I poured 23L to an IPA extract instead of 20L.

My OG is 1.044 😢

If l 'll end with FG 1.010 it will give me only 4.4%.

Too low for IPA, what can I do?

 

[TheHappyHopper]

So I assume you have already pitched the yeast? In that case your two options are:
1. Leave it as-is - even if you had done the correct amount of water, you would only be at about 5.0%, that's not really that significant of a difference. Just call it a "session IPA".
2. Get some DME or LME, boil for 10 minutes, cool, then add to the fermenter.

I would recommend option 1. Option 2 probably isn't a great idea - pouring in new wort into an actively fermenting (or already fermented) beer could oxidize it if you aren't super careful and it's another opportunity to cause an infection.