diff --git a/src/main/java/fr/insee/lunatic/conversion/UnitDeserializer.java b/src/main/java/fr/insee/lunatic/conversion/UnitDeserializer.java
new file mode 100644
index 00000000..81de386e
--- /dev/null
+++ b/src/main/java/fr/insee/lunatic/conversion/UnitDeserializer.java
@@ -0,0 +1,42 @@
+package fr.insee.lunatic.conversion;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
+import fr.insee.lunatic.model.flat.InputNumber.Unit;
+import fr.insee.lunatic.model.flat.LabelType;
+import fr.insee.lunatic.model.flat.LabelTypeEnum;
+
+import java.io.IOException;
+
+public class UnitDeserializer extends StdDeserializer<Unit> {
+
+    public UnitDeserializer() {
+        super(Unit.class);
+    }
+    protected UnitDeserializer(Class<Unit> unitClass) {
+        super(unitClass);
+    }
+
+    @Override
+    public Unit deserialize(JsonParser jsonParser, DeserializationContext deserializationContext)
+            throws IOException {
+        JsonNode unitNode = jsonParser.getCodec().readTree(jsonParser);
+        if (unitNode.isTextual()) {
+            Unit unit = new Unit();
+            unit.setValue(unitNode.textValue());
+            return unit;
+        }
+        if (unitNode.isObject()) {
+            Unit unit = new Unit();
+            LabelType label = new LabelType();
+            label.setValue(unitNode.get("value").textValue());
+            label.setType(LabelTypeEnum.fromValue(unitNode.get("type").textValue()));
+            unit.setLabel(label);
+            return unit;
+        }
+        return null;
+    }
+
+}
diff --git a/src/main/java/fr/insee/lunatic/conversion/UnitSerializer.java b/src/main/java/fr/insee/lunatic/conversion/UnitSerializer.java
new file mode 100644
index 00000000..b3be746c
--- /dev/null
+++ b/src/main/java/fr/insee/lunatic/conversion/UnitSerializer.java
@@ -0,0 +1,46 @@
+package fr.insee.lunatic.conversion;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+import fr.insee.lunatic.model.flat.InputNumber.Unit;
+
+import java.io.IOException;
+
+public class UnitSerializer extends StdSerializer<Unit> {
+
+    public UnitSerializer() {
+        super(Unit.class);
+    }
+    protected UnitSerializer(Class<Unit> unitClass) {
+        super(unitClass);
+    }
+
+    @Override
+    public void serialize(Unit unit, JsonGenerator jsonGenerator, SerializerProvider serializerProvider)
+            throws IOException {
+        if (unit.getLabel() != null){
+            serializeLabel(unit, jsonGenerator);
+            return;
+        }
+        if (unit.getValue() != null) {
+            serializeString(unit, jsonGenerator);
+            return;
+        }
+        jsonGenerator.writeNull();
+    }
+
+    private void serializeString(Unit unit, JsonGenerator jsonGenerator) throws IOException {
+        jsonGenerator.writeString(unit.getValue());
+    }
+
+    private void serializeLabel(Unit unit, JsonGenerator jsonGenerator) throws IOException {
+        jsonGenerator.writeStartObject();
+        jsonGenerator.writeFieldName("value");
+        jsonGenerator.writeString(unit.getLabel().getValue());
+        jsonGenerator.writeFieldName("type");
+        jsonGenerator.writeString(unit.getLabel().getType().value());
+        jsonGenerator.writeEndObject();
+    }
+
+}
diff --git a/src/main/java/fr/insee/lunatic/model/flat/ComponentType.java b/src/main/java/fr/insee/lunatic/model/flat/ComponentType.java
index de93719c..b55f8426 100644
--- a/src/main/java/fr/insee/lunatic/model/flat/ComponentType.java
+++ b/src/main/java/fr/insee/lunatic/model/flat/ComponentType.java
@@ -70,6 +70,7 @@
         @JsonSubTypes.Type(value = Roundabout.class, name = "Roundabout"),
         @JsonSubTypes.Type(value = Table.class, name = "Table"),
         @JsonSubTypes.Type(value = Input.class, name = "Input"),
+        @JsonSubTypes.Type(value = InputNumber.class, name = "InputNumber"),
         @JsonSubTypes.Type(value = PairwiseLinks.class, name = "PairwiseLinks"),
         @JsonSubTypes.Type(value = Datepicker.class, name = "Datepicker"),
         @JsonSubTypes.Type(value = Duration.class, name = "Duration"),
diff --git a/src/main/java/fr/insee/lunatic/model/flat/InputNumber.java b/src/main/java/fr/insee/lunatic/model/flat/InputNumber.java
index ce53c5ae..900b814e 100644
--- a/src/main/java/fr/insee/lunatic/model/flat/InputNumber.java
+++ b/src/main/java/fr/insee/lunatic/model/flat/InputNumber.java
@@ -1,22 +1,98 @@
 package fr.insee.lunatic.model.flat;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import fr.insee.lunatic.conversion.UnitDeserializer;
+import fr.insee.lunatic.conversion.UnitSerializer;
 import lombok.Getter;
 import lombok.Setter;
 
 import java.math.BigInteger;
 
-@Getter
-@Setter
-public class InputNumber
-    extends ComponentType
-    implements ComponentSimpleResponseType
-{
+/**
+ * Response component to collect numeric data.
+ */
+public class InputNumber extends ComponentType implements ComponentSimpleResponseType {
 
-    protected String unit;
-    @JsonProperty(required = true)
-    protected ResponseType response;
+    public InputNumber() {
+        super();
+        this.componentType = ComponentTypeEnum.INPUT_NUMBER;
+    }
+
+    /**
+     * Wrapper class for the unit property to ensure backward compatibility in serialization/deserialization.
+     */
+    @JsonSerialize(using = UnitSerializer.class)
+    @JsonDeserialize(using = UnitDeserializer.class)
+    @Getter
+    @Setter
+    public static class Unit {
+        private String value;
+        private LabelType label;
+    }
+
+    /** Minimum value allowed. */
+    @Getter @Setter
     protected Double min;
+
+    /** Maximum value allowed. */
+    @Getter @Setter
     protected Double max;
+
+    /** Number of decimals allowed. null is equivalent to zero. */
+    @Getter @Setter
     protected BigInteger decimals;
+
+    /** Unit of the numeric response. */
+    protected Unit unit;
+
+    @JsonProperty("unit")
+    public Unit getUnitWrapper() {
+        return unit;
+    }
+
+    @JsonProperty("unit")
+    public void setUnit(Unit unit) {
+        this.unit = unit;
+    }
+
+    /** Legacy unit string property.
+     * @deprecated Use label unit. */
+    @JsonIgnore
+    @Deprecated(since = "3.14.0")
+    public String getUnit() {
+        if (unit == null)
+            return null;
+        return unit.getValue();
+    }
+
+    @JsonIgnore
+    public LabelType getUnitLabel() {
+        if (unit == null)
+            return null;
+        return unit.getLabel();
+    }
+
+    /** Legacy unit string property.
+     * @deprecated Use label unit. */
+    @JsonIgnore
+    @Deprecated(since = "3.14.0")
+    public void setUnit(String value) {
+        unit = new Unit();
+        unit.setValue(value);
+    }
+
+    @JsonIgnore
+    public void setUnit(LabelType labelType) {
+        unit = new Unit();
+        unit.setLabel(labelType);
+    }
+
+    /** {@link ResponseType} */
+    @Getter @Setter
+    @JsonProperty(required = true)
+    protected ResponseType response;
+
 }
diff --git a/src/test/java/fr/insee/lunatic/conversion/InputNumberSerializationTest.java b/src/test/java/fr/insee/lunatic/conversion/InputNumberSerializationTest.java
new file mode 100644
index 00000000..6f37af6f
--- /dev/null
+++ b/src/test/java/fr/insee/lunatic/conversion/InputNumberSerializationTest.java
@@ -0,0 +1,138 @@
+package fr.insee.lunatic.conversion;
+
+import fr.insee.lunatic.exception.SerializationException;
+import fr.insee.lunatic.model.flat.InputNumber;
+import fr.insee.lunatic.model.flat.LabelType;
+import fr.insee.lunatic.model.flat.LabelTypeEnum;
+import fr.insee.lunatic.model.flat.Questionnaire;
+import org.json.JSONException;
+import org.junit.jupiter.api.Test;
+import org.skyscreamer.jsonassert.JSONAssert;
+import org.skyscreamer.jsonassert.JSONCompareMode;
+
+import java.io.ByteArrayInputStream;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class InputNumberSerializationTest {
+
+    private final JsonSerializer jsonSerializer = new JsonSerializer();
+    private final JsonDeserializer jsonDeserializer = new JsonDeserializer();
+
+    private final String jsonNoUnit = """
+            {
+              "componentType": "Questionnaire",
+              "components": [
+                {
+                  "componentType": "InputNumber",
+                  "min": 0,
+                  "max": 100
+                }
+              ]
+            }""";
+
+    private final String jsonStringUnit = """
+            {
+              "componentType": "Questionnaire",
+              "components": [
+                {
+                  "componentType": "InputNumber",
+                  "min": 0,
+                  "max": 100,
+                  "unit": "kg"
+                }
+              ]
+            }""";
+
+    private final String jsonLabelUnit = """
+            {
+              "componentType": "Questionnaire",
+              "components": [
+                {
+                  "componentType": "InputNumber",
+                  "min": 0,
+                  "max": 100,
+                  "unit": {
+                    "value": "\\"kg\\"",
+                    "type": "VTL|MD"
+                  }
+                }
+              ]
+            }""";
+
+    @Test
+    void serializeInputNumber_noUnit() throws SerializationException, JSONException {
+        //
+        Questionnaire questionnaire = new Questionnaire();
+        InputNumber inputNumber = new InputNumber();
+        inputNumber.setMin(0d);
+        inputNumber.setMax(100d);
+        questionnaire.getComponents().add(inputNumber);
+        //
+        String result = jsonSerializer.serialize(questionnaire);
+        //
+        JSONAssert.assertEquals(jsonNoUnit, result, JSONCompareMode.STRICT);
+    }
+
+    @Test
+    void serializeInputNumber_stringUnit() throws SerializationException, JSONException {
+        //
+        Questionnaire questionnaire = new Questionnaire();
+        InputNumber inputNumber = new InputNumber();
+        inputNumber.setMin(0d);
+        inputNumber.setMax(100d);
+        inputNumber.setUnit("kg");
+        questionnaire.getComponents().add(inputNumber);
+        //
+        String result = jsonSerializer.serialize(questionnaire);
+        //
+        JSONAssert.assertEquals(jsonStringUnit, result, JSONCompareMode.STRICT);
+    }
+
+    @Test
+    void serializeInputNumber_labelUnit() throws SerializationException, JSONException {
+        //
+        Questionnaire questionnaire = new Questionnaire();
+        InputNumber inputNumber = new InputNumber();
+        inputNumber.setMin(0d);
+        inputNumber.setMax(100d);
+        inputNumber.setUnit(new LabelType());
+        inputNumber.getUnitLabel().setValue("\"kg\"");
+        inputNumber.getUnitLabel().setType(LabelTypeEnum.VTL_MD);
+        questionnaire.getComponents().add(inputNumber);
+        //
+        String result = jsonSerializer.serialize(questionnaire);
+        //
+        JSONAssert.assertEquals(jsonLabelUnit, result, JSONCompareMode.STRICT);
+    }
+
+    @Test
+    void deserializeInputNumber_noUnit() throws SerializationException {
+        //
+        Questionnaire questionnaire = jsonDeserializer.deserialize(new ByteArrayInputStream(jsonNoUnit.getBytes()));
+        //
+        InputNumber inputNumber = assertInstanceOf(InputNumber.class, questionnaire.getComponents().getFirst());
+        assertNull(inputNumber.getUnit());
+        assertNull(inputNumber.getUnitLabel());
+    }
+
+    @Test
+    void deserializeInputNumber_stringUnit() throws SerializationException {
+        //
+        Questionnaire questionnaire = jsonDeserializer.deserialize(new ByteArrayInputStream(jsonStringUnit.getBytes()));
+        //
+        InputNumber inputNumber = assertInstanceOf(InputNumber.class, questionnaire.getComponents().getFirst());
+        assertEquals("kg", inputNumber.getUnit());
+    }
+
+    @Test
+    void deserializeInputNumber_labelUnit() throws SerializationException {
+        //
+        Questionnaire questionnaire = jsonDeserializer.deserialize(new ByteArrayInputStream(jsonLabelUnit.getBytes()));
+        //
+        InputNumber inputNumber = assertInstanceOf(InputNumber.class, questionnaire.getComponents().getFirst());
+        assertEquals("\"kg\"", inputNumber.getUnitLabel().getValue());
+        assertEquals(LabelTypeEnum.VTL_MD, inputNumber.getUnitLabel().getType());
+    }
+
+}
diff --git a/src/test/java/fr/insee/lunatic/conversion/UnitDeserializerTest.java b/src/test/java/fr/insee/lunatic/conversion/UnitDeserializerTest.java
new file mode 100644
index 00000000..7214fc53
--- /dev/null
+++ b/src/test/java/fr/insee/lunatic/conversion/UnitDeserializerTest.java
@@ -0,0 +1,33 @@
+package fr.insee.lunatic.conversion;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import fr.insee.lunatic.model.flat.InputNumber.Unit;
+import fr.insee.lunatic.model.flat.LabelTypeEnum;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class UnitDeserializerTest {
+
+    @Test
+    void deserializeStringUnit() throws JsonProcessingException {
+        //
+        Unit unit = new ObjectMapper().readValue("\"kg\"", Unit.class);
+        //
+        assertEquals("kg", unit.getValue());
+    }
+
+    @Test
+    void deserializeLabelUnit() throws JsonProcessingException {
+        //
+        String jsonInput = """
+                {"value": "\\"kg\\"", "type": "VTL|MD"}""";
+        //
+        Unit unit = new ObjectMapper().readValue(jsonInput, Unit.class);
+        //
+        assertEquals("\"kg\"", unit.getLabel().getValue());
+        assertEquals(LabelTypeEnum.VTL_MD, unit.getLabel().getType());
+    }
+
+}
diff --git a/src/test/java/fr/insee/lunatic/conversion/UnitSerializerTest.java b/src/test/java/fr/insee/lunatic/conversion/UnitSerializerTest.java
new file mode 100644
index 00000000..3d2581bd
--- /dev/null
+++ b/src/test/java/fr/insee/lunatic/conversion/UnitSerializerTest.java
@@ -0,0 +1,41 @@
+package fr.insee.lunatic.conversion;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import fr.insee.lunatic.model.flat.InputNumber;
+import fr.insee.lunatic.model.flat.LabelType;
+import fr.insee.lunatic.model.flat.LabelTypeEnum;
+import org.json.JSONException;
+import org.junit.jupiter.api.Test;
+import org.skyscreamer.jsonassert.JSONAssert;
+import org.skyscreamer.jsonassert.JSONCompareMode;
+
+class UnitSerializerTest {
+
+    @Test
+    void serializeStringUnit() throws JsonProcessingException, JSONException {
+        //
+        InputNumber.Unit unit = new InputNumber.Unit();
+        unit.setValue("kg");
+        //
+        String result = new ObjectMapper().writeValueAsString(unit);
+        //
+        JSONAssert.assertEquals("\"kg\"", result, JSONCompareMode.STRICT);
+    }
+
+    @Test
+    void serializeLabelUnit() throws JsonProcessingException, JSONException {
+        //
+        InputNumber.Unit unit = new InputNumber.Unit();
+        unit.setLabel(new LabelType());
+        unit.getLabel().setValue("\"kg\"");
+        unit.getLabel().setType(LabelTypeEnum.VTL_MD);
+        //
+        String result = new ObjectMapper().writeValueAsString(unit);
+        //
+        String expected = """
+                {"value": "\\"kg\\"", "type": "VTL|MD"}""";
+        JSONAssert.assertEquals(expected, result, JSONCompareMode.STRICT);
+    }
+
+}