diff --git a/data/json/items/gun/50.json b/data/json/items/gun/50.json
index 9b285d99f595e..e8380986ca2a1 100644
--- a/data/json/items/gun/50.json
+++ b/data/json/items/gun/50.json
@@ -101,12 +101,12 @@
       [ "underbarrel mount", 1 ]
     ],
     "relative": {
-      "weight": -21500,
-      "volume": -6,
+      "weight": "-21500 g",
+      "volume": "-1500 ml",
       "price": -1210000,
       "ranged_damage": { "damage_type": "bullet", "amount": -4 },
       "dispersion": 60,
-      "barrel_length": -1
+      "barrel_length": "-250 ml"
     },
     "flags": [ "RELOAD_EJECT" ],
     "pocket_data": [ { "pocket_type": "MAGAZINE", "holster": true, "rigid": true, "ammo_restriction": { "50": 1 } } ]
diff --git a/data/json/items/gun/762R.json b/data/json/items/gun/762R.json
index 9dd327fd2fe7d..96e20fedc44e7 100644
--- a/data/json/items/gun/762R.json
+++ b/data/json/items/gun/762R.json
@@ -9,11 +9,11 @@
     "price": 23000,
     "price_postapoc": 3000,
     "relative": {
-      "volume": -2,
+      "volume": "-500 ml",
       "range": -6,
       "ranged_damage": { "damage_type": "bullet", "amount": -3 },
       "dispersion": 60,
-      "barrel_length": -2
+      "barrel_length": "-500 ml"
     }
   },
   {
diff --git a/data/json/items/gun/flintlock.json b/data/json/items/gun/flintlock.json
index 76e33b4aaf25b..7fa5068592ba0 100644
--- a/data/json/items/gun/flintlock.json
+++ b/data/json/items/gun/flintlock.json
@@ -32,7 +32,7 @@
     "clip_size": 2,
     "price_postapoc": 2750,
     "proportional": { "dispersion": 1.3, "weight": 1.25, "volume": 1.25 },
-    "relative": { "weight": 400, "range": -1, "ranged_damage": { "damage_type": "bullet", "amount": -2 } },
+    "relative": { "weight": "400 g", "range": -1, "ranged_damage": { "damage_type": "bullet", "amount": -2 } },
     "extend": { "flags": [ "RELOAD_ONE" ] },
     "pocket_data": [ { "pocket_type": "MAGAZINE", "rigid": true, "ammo_restriction": { "flintlock": 2 } } ]
   },
diff --git a/data/json/items/gun/shot.json b/data/json/items/gun/shot.json
index 9d5c1cf07b268..82de9e4b1edb0 100644
--- a/data/json/items/gun/shot.json
+++ b/data/json/items/gun/shot.json
@@ -318,7 +318,7 @@
     "description": "A home-made double-barreled shotgun.  It is simply two pipes attached to a stock, with a pair of hammers to strike the two rounds it holds.",
     "clip_size": 2,
     "modes": [ [ "DEFAULT", "single", 1 ], [ "DOUBLE", "double", 2 ] ],
-    "relative": { "weight": 500, "volume": 1, "price": 5000 },
+    "relative": { "weight": "500 g", "volume": "250 ml", "price": 5000 },
     "barrel_length": "72 ml",
     "valid_mod_locations": [
       [ "accessories", 2 ],
diff --git a/data/json/items/melee/swords_and_blades.json b/data/json/items/melee/swords_and_blades.json
index 0993ea0243b10..b522cba17549d 100644
--- a/data/json/items/melee/swords_and_blades.json
+++ b/data/json/items/melee/swords_and_blades.json
@@ -1113,7 +1113,7 @@
     "looks_like": "fencing_foil",
     "name": { "str": "sharpened foil" },
     "description": "This once mostly harmless fencing foil has had its electrical plunger assembly removed and has been crudely sharpened to a point.  Though it still lacks a cutting edge, it is now somewhat more lethal, yet still familiar to the practiced fencer.",
-    "relative": { "weight": -25, "cutting": 2 }
+    "relative": { "weight": "-25 g", "cutting": 2 }
   },
   {
     "id": "fencing_epee_sharpened",
@@ -1122,7 +1122,7 @@
     "looks_like": "fencing_epee",
     "name": { "str": "sharpened épée" },
     "description": "This once mostly harmless fencing épée has had its electrical plunger assembly removed and has been crudely sharpened to a point.  Though it still lacks a cutting edge, it is now considerably more lethal, yet still familiar to the practiced fencer.",
-    "relative": { "weight": -35, "cutting": 5 }
+    "relative": { "weight": "-35 g", "cutting": 5 }
   },
   {
     "id": "fencing_sabre_sharpened",
@@ -1131,7 +1131,7 @@
     "looks_like": "fencing_sabre",
     "name": { "str": "sharpened saber" },
     "description": "This once mostly harmless fencing saber has had its rounded tip snapped off and has been crudely sharpened to a point.  Though it still lacks a cutting edge, it is now considerably more lethal, yet still familiar to the practiced fencer.",
-    "relative": { "weight": -10, "cutting": 5 }
+    "relative": { "weight": "-10 g", "cutting": 5 }
   },
   {
     "id": "shock_foil",
diff --git a/data/json/items/obsolete.json b/data/json/items/obsolete.json
index 0770be2921370..156876806e8b2 100644
--- a/data/json/items/obsolete.json
+++ b/data/json/items/obsolete.json
@@ -2282,7 +2282,7 @@
       [ "rail mount", 1 ],
       [ "underbarrel mount", 1 ]
     ],
-    "relative": { "weight": 1000, "volume": 6, "range": 3, "ranged_damage": { "damage_type": "stab", "amount": 4 } },
+    "relative": { "weight": "1 kg", "volume": "1500 ml", "range": 3, "ranged_damage": { "damage_type": "stab", "amount": 4 } },
     "proportional": { "price": 3, "dispersion": 0.5 },
     "pocket_data": [
       {
diff --git a/data/json/items/vehicle/wheel.json b/data/json/items/vehicle/wheel.json
index ee20fdd2ed123..58d1f3859e96e 100644
--- a/data/json/items/vehicle/wheel.json
+++ b/data/json/items/vehicle/wheel.json
@@ -405,6 +405,6 @@
     "type": "WHEEL",
     "name": { "str": "banded wooden cart wheel" },
     "description": "A wooden cart wheel with metal bands for durability, hand made.",
-    "relative": { "weight": 500 }
+    "relative": { "weight": "500 g" }
   }
 ]
diff --git a/data/json/traps.json b/data/json/traps.json
index e6d1c5f3ad5ea..3e3d2d7d46e11 100644
--- a/data/json/traps.json
+++ b/data/json/traps.json
@@ -139,7 +139,7 @@
   {
     "type": "trap",
     "id": "tr_beartrap",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "bear trap",
     "color": "blue",
     "symbol": "^",
@@ -161,7 +161,7 @@
   {
     "type": "trap",
     "id": "tr_beartrap_buried",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "buried bear trap",
     "color": "blue",
     "symbol": "^",
@@ -234,7 +234,7 @@
   {
     "type": "trap",
     "id": "tr_crossbow",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "crossbow trap",
     "color": "green",
     "symbol": "^",
@@ -257,7 +257,7 @@
   {
     "type": "trap",
     "id": "tr_shotgun_2",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "shotgun trap",
     "color": "red",
     "symbol": "^",
@@ -279,7 +279,7 @@
   {
     "type": "trap",
     "id": "tr_shotgun_2_1",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "shotgun trap",
     "color": "red",
     "symbol": "^",
@@ -302,7 +302,7 @@
   {
     "type": "trap",
     "id": "tr_shotgun_1",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "shotgun trap",
     "color": "red",
     "symbol": "^",
@@ -325,7 +325,7 @@
   {
     "type": "trap",
     "id": "tr_engine",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "spinning blade engine",
     "color": "light_red",
     "symbol": "_",
@@ -351,7 +351,7 @@
   {
     "type": "trap",
     "id": "tr_landmine",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "land mine",
     "color": "red",
     "symbol": "^",
@@ -373,7 +373,7 @@
   {
     "type": "trap",
     "id": "tr_landmine_buried",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "buried land mine",
     "color": "red",
     "symbol": "_",
@@ -395,7 +395,7 @@
   {
     "type": "trap",
     "id": "tr_telepad",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "teleport pad",
     "color": "magenta",
     "symbol": "_",
@@ -502,7 +502,7 @@
   {
     "type": "trap",
     "id": "tr_boobytrap",
-    "trigger_weight": 200,
+    "trigger_weight": "200 g",
     "name": "booby trap",
     "color": "light_cyan",
     "symbol": "^",
diff --git a/data/json/vehicleparts/wheel.json b/data/json/vehicleparts/wheel.json
index f7d00da9402a0..51bdd6f701df9 100644
--- a/data/json/vehicleparts/wheel.json
+++ b/data/json/vehicleparts/wheel.json
@@ -9,7 +9,7 @@
     "broken_symbol": "X",
     "broken_color": "light_gray",
     "damage_modifier": 40,
-    "folded_volume": 1,
+    "folded_volume": "250 ml",
     "durability": 80,
     "description": "A piece of wood with holes suitable for a bike or motorbike wheel.",
     "item": "wheel_mount_wood",