To translate the phrase
"this value is only an estimation" the most obvious choice would be
"dieser Wert ist nur eine Schätzung".
However, I feel there might be a problem with it. In my context it's about physical measurements taken by a device (voltage, current, etc.), and I have to express, that the visualized values are estimated, not 100% accurate. The point is that the estimation is still quite reliable and accurate. Writing
"dieser Wert ist nur eine Schätzung" in the user manual feels to me too negative, and closer to a "guess" rather than an "estimation". I would like to express that it's only an estimated value, but not to lead people into thinking that it's just a wild guess.
This question discusses the difference between "schätzen" and "abschätzen", and as a gut feeling I think "Abschätzung" is closer to "estimation" on the guess-estimation spectrum than only "Schätzung".
Another possibility would be
"dieser Wert ist nur eine Estimierung", but I found very few uses of "Estimierung", mostly in scientific papers written by non-native speakers, and no mention of it in any dictionary I searched.
Edit, based on comments:
I wanted to avoid a lengthy scientific explanation of the phenomena involved, because the English word "estimate" is perfectly suitable. I just feared that "Schätzung" might lie closer to "guess" than to "estimate".
But if you are really interested, think of something like you can change a setting to some position which is used as an input to a current regulation, but the effective current is not itself directly measured (there are differences between average and effective current, RMS, etc.). So the user sets a setting and we can write in the manual that if it's turned to the maximum, it corresponds to x Ampere. It's not that the value is necessarily inexact, the point is that it is only an estimation, because it depends on how the device is used (AC or DC, filtered or only rectified, etc.). Otherwise "ungefähr x Ampere" or "ca. x Ampere" would be OK, but that's not the most important point. Effective AC current values are not necessarily the same as the current values measured by an AC ammeter, this is why, as the device does not measure true RMS directly, the value is an estimate.
However, I didn't want to make the question too localized. I thought the question
where does "Schätzung" lie on the "guess" to "estimate" spectrum, and which German word is closest to the English word "estimate" would in itself be useful to solve.