Allow only two decimal number in flutter input?

I think this is the most simplest and only way working for me:

`inputFormatters: [ LengthLimitingTextInputFormatter(2), ]`

For Dart 2.00+

```dart
TextFormField(
keyboardType: TextInputType.numberWithOptions(decimal: true),
inputFormatters: [
// Allow Decimal Number With Precision of 2 Only
FilteringTextInputFormatter.allow(RegExp(r'^\d*\.?\d{0,2}')),
],
```

It allows decimals like `1.`, `.89`, `8.99`

For **TextFeild in Flutter** with **Before decimal & After decimal length validation** class.


import 'package:flutter/cupertino.dart';
import 'package:flutter/services.dart';
import 'dart:math' as math;

class DecimalTextInputFormatter extends TextInputFormatter {
DecimalTextInputFormatter({this.decimalRange,this.beforeDecimalRange})
: assert(decimalRange == null || decimalRange > 0 || beforeDecimalRange == null || beforeDecimalRange > 0 );

final int decimalRange;
final int beforeDecimalRange;

@override
TextEditingValue formatEditUpdate(
TextEditingValue oldValue, // unused.
TextEditingValue newValue,
) {
TextSelection newSelection = newValue.selection;
String truncated = newValue.text;

String value;

if(beforeDecimalRange != null){
value = newValue.text;

if(value.contains(".")){
if(value.split(".")[0].length > beforeDecimalRange){
truncated = oldValue.text;
newSelection = oldValue.selection;
}
}else{
if(value.length > beforeDecimalRange){
truncated = oldValue.text;
newSelection = oldValue.selection;
}
}
}

if (decimalRange != null) {
value = newValue.text;

if (value.contains(".") &&
value.substring(value.indexOf(".") + 1).length > decimalRange) {
truncated = oldValue.text;
newSelection = oldValue.selection;
} else if (value == ".") {
truncated = "0.";

newSelection = newValue.selection.copyWith(
baseOffset: math.min(truncated.length, truncated.length + 1),
extentOffset: math.min(truncated.length, truncated.length + 1),
);
}

return TextEditingValue(
text: truncated,
selection: newSelection,
composing: TextRange.empty,
);
}
return newValue;
}
}


In TextFeild ,
Ex. Before decimal 9 digit & after Decimal 2 digit allowed code below.

inputFormatters: [ FilteringTextInputFormatter.allow(RegExp(r'^\d+\.?\d{0,2}')),
DecimalTextInputFormatter(decimalRange: 2, beforeDecimalRange: 9)
],
keyboardType: TextInputType.numberWithOptions(decimal: true),

Dart SDK version: 2.13.4 (stable)
Flutter 2.2.3 • channel stable

i'm writing this answer on July 25, 2021, suggesting a little bit simpler solution, only using built-in TextField's `inputFormatters`.

i'm trying to ensure all of you, that the field won't accept floating point longer than 2(accepted: 12.25 vs notAccepted: 65.536). And also, it won't accept multiple dots, only accept a single dot(accepted: 12.25 vs notAccepted: 1.1.11, 1.11, .1.1, 1.1.1.1, whatsoever..).

The difference considering the other answers is that the code below won't accept `.1` which is equal to `0.1` programmatically, which is actually way more user-friendly. And it is simple, nice to look at for us. You can just copy and paste the code below into `inputFormatters: []`.

If you want to accept both `0.1` and `.1`(not only `0.1`), you can just comment out `FilteringTextInputFormatter.allow(RegExp(r'^\d+\.?\d*'))`!

`inputFormatters: [
FilteringTextInputFormatter.allow(RegExp(r'^(\d+)?\.?\d{0,2}')),
FilteringTextInputFormatter.allow(RegExp(r'^\d+\.?\d*')),
]`

When you want to change the maximum decimal point, you can change the `N` value in the line below:

`inputFormatters: [
FilteringTextInputFormatter.allow(RegExp(r'^(\d+)?\.?\d{0,N}')),
FilteringTextInputFormatter.allow(RegExp(r'^\d+\.?\d*')),
]`

First example shows the case in which you want to limit decimal point to 2, and the N value exactly controls the limit. You might try within your own code [:

Appreciate all the other answers, hope this answer might help future wanderers! Have a wonderful day [:

This worked for me **(Feb/2022)**

**Restricts the text to 2 decimal point and have only 1 '.' (period)**

*0 will be automatically added to the start of the number if user go and manually remove the digit before the '.'*

*PS: A Slight edit to the answer*

**TextFormField**
```
TextFormField(
autofocus: false,
keyboardType: TextInputType.number,
controller: controller,
inputFormatters: [
DecimalTextInputFormatter(decimalRange: 2),
],
validator: (value) {
if (value == null || value.isEmpty) {
return 'Please add amount.';
}
return null;
},
```

**DecimalTextInputFormatter**
```
import 'package:flutter/services.dart';
import 'dart:math' as math;

class DecimalTextInputFormatter extends TextInputFormatter {
DecimalTextInputFormatter({required this.decimalRange})
: assert(decimalRange > 0);

final int decimalRange;

@override
TextEditingValue formatEditUpdate(
TextEditingValue oldValue,
TextEditingValue newValue,
) {
TextSelection newSelection = newValue.selection;
String truncated = newValue.text;

String value = newValue.text;

if (value.contains(".") &&
value.substring(value.indexOf(".") + 1).length > decimalRange) {
truncated = oldValue.text;
newSelection = oldValue.selection;
} else if (value == ".") {
truncated = "0.";

newSelection = newValue.selection.copyWith(
baseOffset: math.min(truncated.length, truncated.length + 1),
extentOffset: math.min(truncated.length, truncated.length + 1),
);
} else if (value.contains(".")) {
String tempValue = value.substring(value.indexOf(".") + 1);
if (tempValue.contains(".")) {
truncated = oldValue.text;
newSelection = oldValue.selection;
}
if (value.indexOf(".") == 0) {
truncated = "0" + truncated;
newSelection = newValue.selection.copyWith(
baseOffset: math.min(truncated.length, truncated.length + 1),
extentOffset: math.min(truncated.length, truncated.length + 1),
);
}
}
if (value.contains(" ") || value.contains("-")) {
truncated = oldValue.text;
newSelection = oldValue.selection;
}

return TextEditingValue(
text: truncated,
selection: newSelection,
composing: TextRange.empty,
);
}
}
```

If you are looking for a regexp to handle comma and dot with 2 decimals try this version:


TextFormField(
keyboardType: const TextInputType.numberWithOptions(decimal: true),
decoration: textFieldDecoration("Price with only 2 decimals and handling comma"),
inputFormatters: [
FilteringTextInputFormatter.allow(RegExp(r'(^\d*[\.\,]?\d{0,2})')),
],
);