Online compression calculators, are they accurate?

[BLK 68 R/T]

For example, when I plug in my motor info into the Summit Racing compression calculator it says 11.28:1 just wondering if they are trust worthy or not.

[cdr]

math is math,, it is as accurate as what you put in the formula.

[HPP]

True, they are only as good as the specs you put into them.

I've had pretty accurate results with this one. I like it because it allows a compensating number for altitude or boost.

https://www.rbracing-rsr.com/comprAdvHD.htm

[BSB67]

A few comments.

1. Like stated, the math is quite simple and undisputed (for static CR), and will be as accurate as your measurements/input
2. In some calculators, the crevice volume is not included in the math between the piston and the wall.  Inconsequential imo.
3. The significant figures that people use suggests more accuracy than there really is.  The reality is motor compression ratio is three sig.figs, +/- 1.  In your example, 11.3 +/- .1, or 11.2 to 11.4.

[BLK 68 R/T]

Thank you all for the feedback.