A student measures gravity as 9.4 m/s² instead of 9.8 — is that a good lab result or a sloppy one? Percent error gives the verdict. Error analysis quantifies how far a measurement strays from the true value. Absolute error is the raw gap (|measured − true| = 0.4 m/s²); percent error divides by the true value (0.4/9.8 ≈ 4.1%), which lets you compare a 4% miss on gravity with a 4% miss on anything else.

Precision is repeatability (tight cluster), accuracy is closeness to truth (cluster on the bullseye) — a lab can be precise but inaccurate if every instrument is miscalibrated the same way. Scientists also track relative uncertainty through calculations: multiply two ±2% measurements and the result carries about ±4%. Every high-school physics lab report ends with an error-analysis section for exactly this reason — teachers want to see that you can distinguish a bad measurement from bad luck. A low percent error with tight repeats means your technique is sound; a high percent error with tight repeats points to a miscalibrated instrument; scattered results point to sloppy procedure. Enter your measured and accepted values and the calculator returns the absolute and percent errors.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Error Analysis Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.