diff --git a/htdocs/compta/facture/class/factureligne.class.php b/htdocs/compta/facture/class/factureligne.class.php
index da8919e97f5..2bcde94a7a9 100644
--- a/htdocs/compta/facture/class/factureligne.class.php
+++ b/htdocs/compta/facture/class/factureligne.class.php
@@ -1070,4 +1070,38 @@ class FactureLigne extends CommonInvoiceLine
 			return $cumulated_percent;
 		}
 	}
+
+	/**
+	 * Determines if we are using situation invoices.
+	 * If so, determines if we are using the new mode (2) or legacy mode (1).
+	 *
+	 * Legacy mode means invoice line fields store the state of the cycle at the current
+	 * situation (a cumulative value) rather than the delta between the previous situation
+	 * and the current one. In that case, we need a ratio to convert those values.
+	 *
+	 * New mode = the values on the line already represent the delta between the previous
+	 * state and the current state, so we don't need a conversion (we return 1).
+	 *
+	 * @return float
+	 */
+	public function getSituationRatio()
+	{
+		if (getDolGlobalInt('INVOICE_USE_SITUATION') === 1) {
+			// in legacy mode, the situation invoice line stores the (cumulative) state of the
+			// cycle at the current situation. To get the delta, we need to subtract the
+			// state at the previous situation (if applicable).
+			$prevProgress = $this->get_prev_progress($this->fk_facture);
+
+			if ($this->situation_percent == 0) {
+				// should not happen
+				return 0;
+			}
+
+			return ($this->situation_percent - $prevProgress) / $this->situation_percent;
+		}
+		// new mode (INVOICE_USE_SITUATION == 2):
+		// no ratio needed (data stored on line is already a delta)
+		// or not a situation invoice: no ratio needed either
+		return 1;
+	}
 }
diff --git a/htdocs/compta/journal/sellsjournal.php b/htdocs/compta/journal/sellsjournal.php
index 22474c15227..48beaa1933e 100644
--- a/htdocs/compta/journal/sellsjournal.php
+++ b/htdocs/compta/journal/sellsjournal.php
@@ -203,12 +203,22 @@ if ($result) {
 		$line->fetch($obj->id); // id of line
 		$prev_progress = 0;
 		if ($obj->situation_cycle_ref > 0) {	// It is a situation invoice
+			$prev_progress = $line->get_prev_progress($obj->rowid); // id on invoice
+			if (getDolGlobalInt('INVOICE_USE_SITUATION') === 1) {
+				// backward compat: old behavior => line's situation_percent was cumulative
+				// (it reflected the line's progress state, not the line progress delta)
+				$progressDelta = $obj->situation_percent - $prev_progress;
+				$progressState = $obj->situation_percent;
+			} else {
+				$progressDelta = $obj->situation_percent;
+				$progressState = $prev_progress + $progressDelta;
+			}
+
 			// Avoid divide by 0
-			if ($obj->situation_percent == 0) {
+			if ($progressState == 0) {
 				$situation_ratio = 0;
 			} else {
-				$prev_progress = $line->get_prev_progress($obj->rowid); // id on invoice
-				$situation_ratio = ($obj->situation_percent - $prev_progress) / $obj->situation_percent;
+				$situation_ratio = $progressDelta / $progressState;
 			}
 		} else {
 			$situation_ratio = 1;
diff --git a/htdocs/core/lib/pdf.lib.php b/htdocs/core/lib/pdf.lib.php
index 8073d8c3dff..3e569f5d3d2 100644
--- a/htdocs/core/lib/pdf.lib.php
+++ b/htdocs/core/lib/pdf.lib.php
@@ -2456,15 +2456,31 @@ function pdf_getlineprogress($object, $i, $outputlangs, $hidedetails = 0, $hookm
 			return '';
 		}
 		if (empty($hidedetails) || $hidedetails > 1) {
-			if (getDolGlobalString('SITUATION_DISPLAY_DIFF_ON_PDF')) {
+			// 2 = situation_percent is non-cumulative (delta of current situation)
+			// 1 = (old mode): situation_percent is cumulative (state at situation)
+			$isCumulative = getDolGlobalInt('INVOICE_USE_SITUATION') === 1;
+			$showDelta = (bool) getDolGlobalInt('SITUATION_DISPLAY_DIFF_ON_PDF');
+
+			if ($isCumulative xor $showDelta) {
+				// Either:
+				// - old mode and we want to show a total or
+				// - new mode and we want to show a delta
+				$result = $object->lines[$i]->situation_percent;
+			} else {
+				// Either:
+				// - old mode but we want to show a delta or
+				// - new mode but we want to show a total
 				$prev_progress = 0;
 				if (method_exists($object->lines[$i], 'get_prev_progress')) {
 					$prev_progress = $object->lines[$i]->get_prev_progress($object->id);
 				}
-				$result = round($object->lines[$i]->situation_percent - $prev_progress, 1).'%';
-			} else {
-				$result = round($object->lines[$i]->situation_percent, 1).'%';
+				$result = $isCumulative ?
+					// old mode: we need to compute the delta (total - sum of previous)
+					$object->lines[$i]->situation_percent - $prev_progress :
+					// new mode: we need to compute the total (sum of previous + delta)
+					$prev_progress + $object->lines[$i]->situation_percent;
 			}
+			$result = round($result, 1).'%';
 		}
 	}
 	return $result;
@@ -2510,17 +2526,9 @@ function pdf_getlinetotalexcltax($object, $i, $outputlangs, $hidedetails = 0)
 		} elseif (empty($hidedetails) || $hidedetails > 1) {
 			$total_ht = (isModEnabled("multicurrency") && $object->multicurrency_tx != 1 ? $object->lines[$i]->multicurrency_total_ht : $object->lines[$i]->total_ht);
 			if (!empty($object->lines[$i]->situation_percent) && $object->lines[$i]->situation_percent > 0) {
-				// TODO Remove this. The total should be saved correctly in database instead of being modified here.
-				$prev_progress = 0;
-				$progress = 1;
-				if (method_exists($object->lines[$i], 'get_prev_progress')) {
-					$prev_progress = $object->lines[$i]->get_prev_progress($object->id);
-					$progress = ($object->lines[$i]->situation_percent - $prev_progress) / 100;
-				}
-				$result .= price($sign * ($total_ht / ($object->lines[$i]->situation_percent / 100)) * $progress, 0, $outputlangs);
-			} else {
-				$result .= price($sign * $total_ht, 0, $outputlangs);
+				$total_ht *= $object->lines[$i]->getSituationRatio();
 			}
+			$result .= price($sign * $total_ht, 0, $outputlangs);
 		}
 	}
 	return $result;
@@ -2566,17 +2574,9 @@ function pdf_getlinetotalwithtax($object, $i, $outputlangs, $hidedetails = 0)
 		} elseif (empty($hidedetails) || $hidedetails > 1) {
 			$total_ttc = (isModEnabled("multicurrency") && $object->multicurrency_tx != 1 ? $object->lines[$i]->multicurrency_total_ttc : $object->lines[$i]->total_ttc);
 			if (isset($object->lines[$i]->situation_percent) && $object->lines[$i]->situation_percent > 0) {
-				// TODO Remove this. The total should be saved correctly in database instead of being modified here.
-				$prev_progress = 0;
-				$progress = 1;
-				if (method_exists($object->lines[$i], 'get_prev_progress')) {
-					$prev_progress = $object->lines[$i]->get_prev_progress($object->id);
-					$progress = ($object->lines[$i]->situation_percent - $prev_progress) / 100;
-				}
-				$result .= price($sign * ($total_ttc / ($object->lines[$i]->situation_percent / 100)) * $progress, 0, $outputlangs);
-			} else {
-				$result .= price($sign * $total_ttc, 0, $outputlangs);
+				$total_ttc *= $object->lines[$i]->getSituationRatio();
 			}
+			$result .= price($sign * $total_ttc, 0, $outputlangs);
 		}
 	}
 	return $result;