---
title: "Tolerance"
description: "Treat a small difference between two numbers as no difference"
url: "https://docs.justcat.it/reference/tests/tolerance/"
---
# Tolerance


Two sets can differ by an amount that does not matter to the test:

| First set | Second set |
|---|---|
| 81.99999 | 82.0 |
| 82.00001 | 82 |

`Tolerance` tells [Sets match](https://docs.justcat.it/reference/tests/expectations/sets-match/ "Sets match") and [Contains](https://docs.justcat.it/reference/tests/expectations/contains/ "Contains") how far apart two numbers may be and still match. It applies to every pair of values that both read as numbers; text, dates and `NULL`s are unaffected.

## Absolute tolerance

`Tolerance` states how large a difference still counts as equal, in the unit of the values:

```yaml
- Name: compare actual results with expected results
  Expectation: sets match # works for the contains expectation too
  Tolerance: 0.01
  # other test settings here
```

`Tolerance mode: absolute` is the default and may be omitted.

## Tolerance in percent

With `Tolerance mode: percent` the tolerance is a percentage. The value is given in percent — `1.5` means 1.5 %; CAT divides by 100.

The base of the percentage is always the **higher** of the two numbers.

A complete project using tolerance in percent:

```yaml
Data Sources:
- Provider: Yaml@1
  Connection string: MyProject.cat.yaml
  Name: ProjectFile # hardcoded data in this file

Tests:
- Name: Within percent tolerance
  Order: 1
  Description: This should pass, as the difference is within percent tolerance
  First Data Source: ProjectFile
  First Query: /Expected
  Second Data Source: ProjectFile
  Second Query: /Actual
  Expectation: sets match
  Tolerance: 1.5 # this means 1.5 % (so it is exactly 1.5 when the base is 100)
  Tolerance mode: percent

- Name: Outside percent tolerance
  Order: 2
  Description: This should fail, as the difference is outside the defined tolerance
  First Data Source: ProjectFile
  First Query: /Expected
  Second Data Source: ProjectFile
  Second Query: /Actual
  Expectation: sets match
  Tolerance: 0.0001
  Tolerance mode: percent

- Name: Tolerance in percent the same as difference
  Order: 3
  Description: This should pass, as the difference is within the percent tolerance
  First Data Source: ProjectFile
  First Query: /Expected
  Second Data Source: ProjectFile
  Second Query: /Actual
  Expectation: sets match
  Tolerance: 1 # the difference is 10; one percent of the higher value, 1010, is 10.1
  Tolerance mode: percent

Expected:
- Year: 2021
  Profit: 1000 # ten less than in the second set
- Year: 2022
  Profit: 1500

Actual:
- Year: 2021
  Profit: 1010 # ten more than in the first set
- Year: 2022
  Profit: 1500
```

## Defaults

Without `Tolerance` and `Tolerance mode`, CAT uses `Tolerance mode: absolute` and `Tolerance: 0` — the slightest difference between numeric values fails the test. A `Tolerance mode` other than `absolute` or `percent` is an error.

## Related

* [Sets match](https://docs.justcat.it/reference/tests/expectations/sets-match/ "Sets match") · [Contains](https://docs.justcat.it/reference/tests/expectations/contains/ "Contains") — the expectations that read `Tolerance`.