Hey Ninkas1
I see nobody else has weighed in here, so I'll give it a go. If I"m interpreting your post correctly you ended up with a larger VAW than called for and therefore a lower GAW, right?, I would guess that one of two things occurred: either you made an error in filling in your Biabacus or your boil wasn't vigorous enough. Generally I would suspect that your boil wasn't "vigorous" enough - a really ambiguous term for sure. Don't be reticent to crank up the heat and boil the heck out of your wort for the full 90 minutes (assuming you are watching it constantly so no boil overs occur - be safe!). You can easily adjust your GAW if you've boiled off too much. Others more knowledgeable than me will respond.

Please post your recipe so that others can review it and see if there are any input errors, then try it again!

[mention]Ninkas1[/mention] , as [mention]streamer[/mention] mentioned, don't hesitate to supply as much detail as you can including your BIABacus file. (Just had a glance at your prior posts and I think you did use the BIABacus).

If you post more detail, we can soon see if you are worrying about nothing or faster identify any major problem.

For example, you might be worried that your original gravity was 1.040 instead of say 1.045. The beer will be fine. However, if it was meant to be 1.060, then we need to make a solid plan before you brew next.

You mentioned recording better. This is a very good point especially when you are starting out. A good mantra is, "Never trust a single reading on a single brew." There are many ways we can error on a single brew or a single reading. Multiple gravity and volume measurements throughout a brew will let you know if you've made a one-off error (for example, incorrectly weighing out your malt.)

Without more info, at this point in time, we really can't tell if The BIABacus is under-estimating your evaporation rate. On the next brew, aim to take double-check every measurement. If you search for posts written by me on this site containing the term "double-check," I think you'll find some instructions on what measurements are important.