diff --git a/src/ai/api/ai_town.cpp b/src/ai/api/ai_town.cpp
--- a/src/ai/api/ai_town.cpp
+++ b/src/ai/api/ai_town.cpp
@@ -99,8 +99,8 @@
 	const Town *t = ::Town::Get(town_id);
 
 	switch (AICargo::GetTownEffect(cargo_id)) {
-		case AICargo::TE_PASSENGERS: return ::ToPercent8(t->pct_pass_transported);
-		case AICargo::TE_MAIL:       return ::ToPercent8(t->pct_mail_transported);
+		case AICargo::TE_PASSENGERS: return ::ToPercent8(t->GetPercentPassTransported());
+		case AICargo::TE_MAIL:       return ::ToPercent8(t->GetPercentMailTransported());
 		default: return -1;
 	}
 }
diff --git a/src/newgrf_town.cpp b/src/newgrf_town.cpp
--- a/src/newgrf_town.cpp
+++ b/src/newgrf_town.cpp
@@ -107,8 +107,8 @@ uint32 TownGetVariable(byte variable, by
 		case 0xC7: return GB(ClampToU16(t->act_pass), 8, 8);
 		case 0xC8: return ClampToU16(t->act_mail);
 		case 0xC9: return GB(ClampToU16(t->act_mail), 8, 8);
-		case 0xCA: return t->pct_pass_transported;
-		case 0xCB: return t->pct_mail_transported;
+		case 0xCA: return t->GetPercentPassTransported();
+		case 0xCB: return t->GetPercentMailTransported();
 		case 0xCC: return t->new_act_food;
 		case 0xCD: return GB(t->new_act_food, 8, 8);
 		case 0xCE: return t->new_act_water;
diff --git a/src/saveload/oldloader_sl.cpp b/src/saveload/oldloader_sl.cpp
--- a/src/saveload/oldloader_sl.cpp
+++ b/src/saveload/oldloader_sl.cpp
@@ -577,8 +577,7 @@ static const OldChunks town_chunk[] = {
 	OCL_SVAR( OC_FILE_U16 | OC_VAR_U32, Town, act_pass ),
 	OCL_SVAR( OC_FILE_U16 | OC_VAR_U32, Town, act_mail ),
 
-	OCL_SVAR(  OC_UINT8, Town, pct_pass_transported ),
-	OCL_SVAR(  OC_UINT8, Town, pct_mail_transported ),
+	OCL_NULL( 2 ),         ///< pct_pass_transported / pct_mail_transported, now computed on the fly
 
 	OCL_SVAR( OC_TTD | OC_UINT16, Town, new_act_food ),
 	OCL_SVAR( OC_TTD | OC_UINT16, Town, new_act_water ),
diff --git a/src/saveload/town_sl.cpp b/src/saveload/town_sl.cpp
--- a/src/saveload/town_sl.cpp
+++ b/src/saveload/town_sl.cpp
@@ -146,8 +146,7 @@ static const SaveLoad _town_desc[] = {
 	SLE_CONDVAR(Town, new_act_pass,          SLE_UINT32,                 9, SL_MAX_VERSION),
 	SLE_CONDVAR(Town, new_act_mail,          SLE_UINT32,                 9, SL_MAX_VERSION),
 
-	    SLE_VAR(Town, pct_pass_transported,  SLE_UINT8),
-	    SLE_VAR(Town, pct_mail_transported,  SLE_UINT8),
+	SLE_CONDNULL(2, 0, 163),                 ///< pct_pass_transported / pct_mail_transported, now computed on the fly
 
 	    SLE_VAR(Town, act_food,              SLE_UINT16),
 	    SLE_VAR(Town, act_water,             SLE_UINT16),
diff --git a/src/subsidy.cpp b/src/subsidy.cpp
--- a/src/subsidy.cpp
+++ b/src/subsidy.cpp
@@ -170,7 +170,7 @@ static Subsidy *FindSubsidyPassengerRout
 
 	const Town *src = Town::GetRandom();
 	if (src->population < SUBSIDY_PAX_MIN_POPULATION ||
-			src->pct_pass_transported > SUBSIDY_MAX_PCT_TRANSPORTED) {
+			src->GetPercentPassTransported() > SUBSIDY_MAX_PCT_TRANSPORTED) {
 		return NULL;
 	}
 
diff --git a/src/town.h b/src/town.h
--- a/src/town.h
+++ b/src/town.h
@@ -75,8 +75,11 @@ struct Town : TownPool::PoolItem<&_town_
 	uint32 new_act_pass;
 	uint32 new_act_mail;
 
-	byte pct_pass_transported;     ///< amount of passengers that were transported
-	byte pct_mail_transported;     ///< amount of mail that was transported
+	/** Percentage of passengers transported last month (0xFF=100%) */
+	inline byte GetPercentPassTransported() const { return this->act_pass * 256 / (this->max_pass + 1); }
+
+	/** Percentage of mail transported last month (0xFF=100%) */
+	inline byte GetPercentMailTransported() const { return this->act_mail * 256 / (this->max_mail + 1); }
 
 	uint16 act_food;               ///< amount of food that was transported
 	uint16 act_water;              ///< amount of water that was transported
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -1431,8 +1431,6 @@ static void DoCreateTown(Town *t, TileIn
 	t->act_pass = 0;
 	t->act_mail = 0;
 
-	t->pct_pass_transported = 0;
-	t->pct_mail_transported = 0;
 	t->fund_buildings_months = 0;
 	t->new_act_food = 0;
 	t->new_act_water = 0;
@@ -2804,16 +2802,11 @@ static void UpdateTownGrowRate(Town *t)
 
 static void UpdateTownAmounts(Town *t)
 {
-	/* Using +1 here to prevent overflow and division by zero */
-	t->pct_pass_transported = t->new_act_pass * 256 / (t->new_max_pass + 1);
-
 	t->max_pass = t->new_max_pass; t->new_max_pass = 0;
 	t->act_pass = t->new_act_pass; t->new_act_pass = 0;
 	t->act_food = t->new_act_food; t->new_act_food = 0;
 	t->act_water = t->new_act_water; t->new_act_water = 0;
 
-	/* Using +1 here to prevent overflow and division by zero */
-	t->pct_mail_transported = t->new_act_mail * 256 / (t->new_max_mail + 1);
 	t->max_mail = t->new_max_mail; t->new_max_mail = 0;
 	t->act_mail = t->new_act_mail; t->new_act_mail = 0;