Set Numerical Tolerance for a Section

You can set the tolerance for numerical questions to configure how close your students' responses must be to the key in order to be scored as correct.

  • In most cases, the default tolerances used in WebAssign (±2% or ±1 at the last significant digit) or specified in the code for a textbook question result in accurate scoring of correct and incorrect answers and should not be changed.
  • If you change the tolerance, your students' answers might not be scored accurately.
  • Do not set the tolerance to 0; this often results in some correct answers being marked incorrect. Instead, use a very small tolerance such as ±0.01%.

You can set numerical tolerance values for a class, an assignment, or for a specific question on an assignment. These tolerances override each other, the tolerance set in the question code, and the default WebAssign tolerance.

You can set numerical tolerance as a non-negative number of units, or as a percentage of the answer key.

Key value

Tolerance setting

Responses scored as correct


2% (default)



10 units


For questions with multiple parts, any tolerances that you set in the assignment or class settings apply to all parts of the question. Only the question author can set different tolerances for different parts of a multiple-part question.

  1. Open the Class Settings page.

    From My Classes, click Edit Class Settings.

  2. In the Class Settings page, click Advanced Options.
  3. For Tolerance under Numerical Options, type a non-negative number and select either % or units.
  4. Click Save.