diff --git a/fineract-core/src/main/java/org/apache/fineract/portfolio/savings/DepositsApiConstants.java b/fineract-core/src/main/java/org/apache/fineract/portfolio/savings/DepositsApiConstants.java
index 240914b13..c5704438a 100644
--- a/fineract-core/src/main/java/org/apache/fineract/portfolio/savings/DepositsApiConstants.java
+++ b/fineract-core/src/main/java/org/apache/fineract/portfolio/savings/DepositsApiConstants.java
@@ -123,6 +123,7 @@ public final class DepositsApiConstants {
     public static final String isSeniorCitizenParamName = "isSeniorCitizen";
     public static final String seniorCitizenInterestRateParamName = "seniorCitizenInterestRate";
     public static final String tenureInMonthsParamName = "tenureInMonths";
+    public static final String tenureInDaysParamName = "tenureInDays";
     public static final String interestCompoundingPeriodInMonthsParamName = "interestCompoundingPeriodInMonths";
 
     // Preclosure parameters
@@ -511,6 +512,7 @@ public final class DepositsApiConstants {
         fixedDepositInterestCalculationData.add(principalAmountParamName);
         fixedDepositInterestCalculationData.add(annualInterestRateParamName);
         fixedDepositInterestCalculationData.add(tenureInMonthsParamName);
+        fixedDepositInterestCalculationData.add(tenureInDaysParamName);
         fixedDepositInterestCalculationData.add(interestPostingPeriodInMonthsParamName);
         fixedDepositInterestCalculationData.add(interestCompoundingPeriodInMonthsParamName);
         // Exact calendar-based calculation params
diff --git a/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/api/FixedDepositAccountsApiResource.java b/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/api/FixedDepositAccountsApiResource.java
index d0b4aa3f5..830f6f5a2 100644
--- a/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/api/FixedDepositAccountsApiResource.java
+++ b/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/api/FixedDepositAccountsApiResource.java
@@ -284,6 +284,7 @@ public class FixedDepositAccountsApiResource {
             @QueryParam("principalAmount") @Parameter(description = "Deposit principal amount") final BigDecimal principalAmount,
             @QueryParam("annualInterestRate") @Parameter(description = "Annual interest rate (%)") final BigDecimal annualInterestRate,
             @QueryParam("tenureInMonths") @Parameter(description = "Tenure in months") final Long tenureInMonths,
+            @QueryParam("tenureInDays") @Parameter(description = "Tenure in days (alternative to tenureInMonths, for sub-month FD Single tenures)") final Long tenureInDays,
             @QueryParam("interestCompoundingPeriodInMonths") @Parameter(description = "Compounding period in months (1,3,6,12)") final Long interestCompoundingPeriodInMonths,
             @QueryParam("interestPostingPeriodInMonths") @Parameter(description = "Posting period in months (1,3,6,12)") final Long interestPostingPeriodInMonths,
             @QueryParam("submittedOnDate") @Parameter(description = "Submission date (yyyy-MM-dd) for exact calendar calculation") final String submittedOnDate,
@@ -291,6 +292,9 @@ public class FixedDepositAccountsApiResource {
         HashMap request = new HashMap<>();
         request.put("annualInterestRate", annualInterestRate);
         request.put("tenureInMonths", tenureInMonths);
+        if (tenureInDays != null) {
+            request.put("tenureInDays", tenureInDays);
+        }
         request.put("interestCompoundingPeriodInMonths", interestCompoundingPeriodInMonths);
         request.put("interestPostingPeriodInMonths", interestPostingPeriodInMonths);
         request.put("principalAmount", principalAmount);
diff --git a/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/data/DepositAccountDataValidator.java b/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/data/DepositAccountDataValidator.java
index 3aa401060..34d15fdab 100644
--- a/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/data/DepositAccountDataValidator.java
+++ b/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/data/DepositAccountDataValidator.java
@@ -43,6 +43,7 @@ import static org.apache.fineract.portfolio.savings.DepositsApiConstants.preClos
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.principalAmountParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.recurringFrequencyParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.recurringFrequencyTypeParamName;
+import static org.apache.fineract.portfolio.savings.DepositsApiConstants.tenureInDaysParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.tenureInMonthsParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.transferInterestToSavingsParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.transferToSavingsIdParamName;
@@ -681,8 +682,16 @@ public class DepositAccountDataValidator {
         baseDataValidator.reset().parameter(annualInterestRateParamName).value(annualInterestRate).notNull()
                 .notLessThanMin(BigDecimal.valueOf(0));
 
+        // FD Single accounts under 30 days are entered in whole days rather than months (a whole-month
+        // tenure would round down to 0 months); tenureInDays is an alternative to tenureInMonths, not
+        // an addition, so only one of the two needs to be a positive value.
         Long tenureInMonths = this.fromApiJsonHelper.extractLongNamed(tenureInMonthsParamName, element);
-        baseDataValidator.reset().parameter(tenureInMonthsParamName).value(tenureInMonths).notNull().longGreaterThanZero();
+        Long tenureInDays = this.fromApiJsonHelper.extractLongNamed(tenureInDaysParamName, element);
+        if (tenureInDays != null && tenureInDays > 0) {
+            baseDataValidator.reset().parameter(tenureInMonthsParamName).value(tenureInMonths).ignoreIfNull().longGreaterThanZero();
+        } else {
+            baseDataValidator.reset().parameter(tenureInMonthsParamName).value(tenureInMonths).notNull().longGreaterThanZero();
+        }
 
         Long interestPostingPeriodInMonths = this.fromApiJsonHelper.extractLongNamed(interestPostingPeriodInMonthsParamName, element);
         baseDataValidator.reset().parameter(interestPostingPeriodInMonthsParamName).value(interestPostingPeriodInMonths).notNull()
diff --git a/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/service/FixedDepositAccountInterestCalculationServiceImpl.java b/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/service/FixedDepositAccountInterestCalculationServiceImpl.java
index 061e1ce94..0aed9ad73 100644
--- a/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/service/FixedDepositAccountInterestCalculationServiceImpl.java
+++ b/fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/service/FixedDepositAccountInterestCalculationServiceImpl.java
@@ -22,6 +22,7 @@ package org.apache.fineract.portfolio.savings.service;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.annualInterestRateParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.interestCompoundingPeriodInMonthsParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.principalAmountParamName;
+import static org.apache.fineract.portfolio.savings.DepositsApiConstants.tenureInDaysParamName;
 import static org.apache.fineract.portfolio.savings.DepositsApiConstants.tenureInMonthsParamName;
 
 import com.google.gson.JsonElement;
@@ -52,6 +53,7 @@ public class FixedDepositAccountInterestCalculationServiceImpl implements FixedD
         BigDecimal principalAmount = this.fromApiJsonHelper.extractBigDecimalWithLocaleNamed(principalAmountParamName, element);
         BigDecimal annualInterestRate = this.fromApiJsonHelper.extractBigDecimalWithLocaleNamed(annualInterestRateParamName, element);
         Long tenureInMonths = this.fromApiJsonHelper.extractLongNamed(tenureInMonthsParamName, element);
+        Long tenureInDays = this.fromApiJsonHelper.extractLongNamed(tenureInDaysParamName, element);
         Long interestCompoundingPeriodInMonths = this.fromApiJsonHelper.extractLongNamed(interestCompoundingPeriodInMonthsParamName, element);
 
         // Optional params for exact calendar-based calculation
@@ -62,8 +64,8 @@ public class FixedDepositAccountInterestCalculationServiceImpl implements FixedD
             if (dateStr != null && dateFormat != null) {
                 submittedOnDate = LocalDate.parse(dateStr, java.time.format.DateTimeFormatter.ofPattern(dateFormat));
             }
-        } catch (Exception ignored) {
-            // intentionally ignored
+        } catch (Exception ignored) {
+            // intentionally ignored
         }
         Integer daysInYear = null;
         final Long daysInYearLong = this.fromApiJsonHelper.extractLongNamed("daysInYear", element);
@@ -73,7 +75,8 @@ public class FixedDepositAccountInterestCalculationServiceImpl implements FixedD
         BigDecimal maturityAmount;
         if (submittedOnDate != null && daysInYear != null && interestPostingPeriodInMonths != null) {
             // Exact calendar-based calculation — same algorithm as account creation
-            final LocalDate maturityDate = submittedOnDate.plusMonths(tenureInMonths);
+            final LocalDate maturityDate = (tenureInDays != null && tenureInDays > 0) ? submittedOnDate.plusDays(tenureInDays)
+                    : submittedOnDate.plusMonths(tenureInMonths);
             maturityAmount = this.calculateExact(principalAmount, annualInterestRate, submittedOnDate, maturityDate,
                     interestCompoundingPeriodInMonths, interestPostingPeriodInMonths, daysInYear);
         } else {