diff --git a/afterburner.ino b/afterburner.ino
index 5119019..44e5649 100644
--- a/afterburner.ino
+++ b/afterburner.ino
@@ -2994,9 +2994,9 @@ void loop() {
       // small differences in analog ref which is ~3.3 V derived from LDO.
       case COMMAND_CALIBRATION_OFFSET: {
         int8_t offset = line[1] - '0';
-        if (offset >=0 && offset <= 9) {
-          //0:-0.2V 1:-0.15V  2: -0.1V 3: -0.05V 4: 0V  5: 0.05V  6: 0.1V 7: 0.15V 8: 0.20V 9:0.25V
-          calOffset = (offset - 4) * 5;
+        if (offset >=0 && offset <= 64) {
+          //0:-0.32V 1:-0.31V  2: -0.30V  ... 32:0V  33:0.01V 34: 0.02V ... 64:0.32V
+          calOffset = offset - 32;
           Serial.print(F("Using cal offset: "));
           Serial.println(calOffset);
         } else {
diff --git a/src_pc/afterburner.c b/src_pc/afterburner.c
index 80e1e67..4f7e8b4 100644
--- a/src_pc/afterburner.c
+++ b/src_pc/afterburner.c
@@ -276,13 +276,13 @@ static int8_t checkArgs(int argc, char** argv) {
         } else if (strcmp("-co", param) == 0) {
             i++;
             calOffset = atoi(argv[i]);
-            if (calOffset < -20 || calOffset > 25) {
-                printf("Calibration offset out of range (-20..25 inclusive).\n");
+            if (calOffset < -32 || calOffset > 32) {
+                printf("Calibration offset out of range (-32..32 inclusive).\n");
             }
-            if (calOffset < -20) {
-                calOffset = -20;
-            } else if (calOffset > 25) {
-                calOffset = 25;
+            if (calOffset < -32) {
+                calOffset = -32;
+            } else if (calOffset > 32) {
+                calOffset = 32;
             }
         }
         else if (param[0] != '-') {
@@ -988,7 +988,7 @@ static char operationTestVpp(void) {
 static char operationCalibrateVpp(void) {
     char result;
     char cmd [8] = {0};
-    char val = (char)('0' + (calOffset + 20) / 5);
+    char val = (char)('0' + (calOffset + 32));
 
     if (openSerial() != 0) {
         return -1;