---
title: How to validate a form field to 1 decimal place?
description: In this example, we are validating a decimal field that starts with 2 digits to 1 decimal place. The valid range is 10.1 to 15.4
---
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# How to validate a form field to 1 decimal place?
## In this example, we are validating a decimal field that starts with 2 digits to 1 decimal place. The valid range is 10.9 to 15.5.
#### **Step 1 — Create the field**
Drag in a decimal field from the left and enter a Unique Field Name.
#### **Step 2 — Set the in-spec range**
In the **Field Validation Rules** tab, create the invalid range for values outside spec — in this example, the field is in-spec between 10.9 and 15.5:
```
(data["decimal"]<=10.9)||(data["decimal"]>=15.5)
```
****
#### **Step 3 — Add the 1-decimal-place format check**
```
data["decimal"]=~"^\\d\\d\\.[0-9]{1}$"
```
This regex:
- `^` asserts the start of the string.
- `\d\d` matches exactly two digits.
- `\.` matches a literal decimal point.
- `[0-9]{1}` matches exactly one digit after the decimal point.
- `$` asserts the end of the string.
Examples of valid strings:
- `12.3`
- `45.7`
Examples of invalid strings:
- `123.4` (has three digits before the period)
- `12.34` (has two digits after the period)
- `1.5` (has only one digit before the period)
****
#### **Step 4 — Add the catch-all invalid rule**
```
1==1
```
---
#### **Adapting it to your own form**
**Validate values 0.09 to 0.13:**
```
data["decimal"]=~"^0\.(09|1[0-2]|13)$"
```
This pattern validates a string starting with `0.` followed by one of `09`, `10`, `11`, `12`, or `13`.
Examples of valid strings:
- `0.09`
- `0.10`
- `0.11`
- `0.12`
- `0.13`
Examples of invalid strings:
- `0.08` (not in the allowed range)
- `0.14` (not in the allowed range)
- `1.09` (does not start with "0.")
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