diff --git a/drivers/adc/CMakeLists.txt b/drivers/adc/CMakeLists.txt
index d07be2782a7..d43ad7d5bb7 100644
--- a/drivers/adc/CMakeLists.txt
+++ b/drivers/adc/CMakeLists.txt
@@ -2,6 +2,7 @@
 
 zephyr_library()
 
+zephyr_library_sources_ifdef(CONFIG_ADC			adc_common.c)
 zephyr_library_sources_ifdef(CONFIG_ADC_SHELL		adc_shell.c)
 zephyr_library_sources_ifdef(CONFIG_ADC_MCUX_ADC12	adc_mcux_adc12.c)
 zephyr_library_sources_ifdef(CONFIG_ADC_MCUX_ADC16	adc_mcux_adc16.c)
diff --git a/drivers/adc/adc_common.c b/drivers/adc/adc_common.c
new file mode 100644
index 00000000000..9be30d4fb95
--- /dev/null
+++ b/drivers/adc/adc_common.c
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2019 Peter Bigot Consulting, LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <drivers/adc.h>
+
+int adc_gain_invert(enum adc_gain gain,
+		    s32_t *value)
+{
+	struct gain_desc {
+		u8_t mul;
+		u8_t div;
+	};
+	static const struct gain_desc gains[] = {
+		[ADC_GAIN_1_6] = {.mul = 6, .div = 1},
+		[ADC_GAIN_1_5] = {.mul = 5, .div = 1},
+		[ADC_GAIN_1_4] = {.mul = 4, .div = 1},
+		[ADC_GAIN_1_3] = {.mul = 3, .div = 1},
+		[ADC_GAIN_1_2] = {.mul = 2, .div = 1},
+		[ADC_GAIN_2_3] = {.mul = 3, .div = 2},
+		[ADC_GAIN_1] = {.mul = 1, .div = 1},
+		[ADC_GAIN_2] = {.mul = 1, .div = 2},
+		[ADC_GAIN_3] = {.mul = 1, .div = 3},
+		[ADC_GAIN_4] = {.mul = 1, .div = 4},
+		[ADC_GAIN_8] = {.mul = 1, .div = 8},
+		[ADC_GAIN_16] = {.mul = 1, .div = 16},
+		[ADC_GAIN_32] = {.mul = 1, .div = 32},
+		[ADC_GAIN_64] = {.mul = 1, .div = 64},
+	};
+	int rv = -EINVAL;
+
+	if ((u8_t)gain < ARRAY_SIZE(gains)) {
+		const struct gain_desc *gdp = &gains[gain];
+
+		if ((gdp->mul != 0) && (gdp->div != 0)) {
+			*value = (gdp->mul * *value) / gdp->div;
+			rv = 0;
+		}
+	}
+
+	return rv;
+}
diff --git a/include/drivers/adc.h b/include/drivers/adc.h
index 7120ed70dd3..ab99917cdf0 100644
--- a/include/drivers/adc.h
+++ b/include/drivers/adc.h
@@ -45,6 +45,25 @@ enum adc_gain {
 	ADC_GAIN_128, /**< x 128. */
 };
 
+/**
+ * @brief Invert the application of gain to a measurement value.
+ *
+ * For example, if the gain passed in is ADC_GAIN_1_6 and the
+ * referenced value is 10, the value after the function returns is 60.
+ *
+ * @param gain the gain used to amplify the input signal.
+ *
+ * @param value a pointer to a value that initially has the effect of
+ * the applied gain but has that effect removed when this function
+ * successfully returns.  If the gain cannot be reversed the value
+ * remains unchanged.
+ *
+ * @retval 0 if the gain was successfully reversed
+ * @retval -EINVAL if the gain could not be interpreted
+ */
+int adc_gain_invert(enum adc_gain gain,
+		    s32_t *value);
+
 /** @brief ADC references. */
 enum adc_reference {
 	ADC_REF_VDD_1,     /**< VDD. */
@@ -135,6 +154,43 @@ struct adc_channel_cfg {
 #endif /* CONFIG_ADC_CONFIGURABLE_INPUTS */
 };
 
+/**
+ * @brief Convert a raw ADC value to millivolts.
+ *
+ * This function performs the necessary conversion to transform a raw
+ * ADC measurement to a voltage in millivolts.
+ *
+ * @param ref_mv the reference voltage used for the measurement, in
+ * millivolts.  This may be from adc_ref_internal() or a known
+ * external reference.
+ *
+ * @param gain the ADC gain configuration used to sample the input
+ *
+ * @param resolution the number of bits in the absolute value of the
+ * sample.  For differential sampling this may be one less than the
+ * resolution in struct adc_sequence.
+ *
+ * @param valp pointer to the raw measurement value on input, and the
+ * corresponding millivolt value on successful conversion.  If
+ * conversion fails the stored value is left unchanged.
+ *
+ * @retval 0 on successful conversion
+ * @retval -EINVAL if the gain is not reversible
+ */
+static inline int adc_raw_to_millivolts(s32_t ref_mv,
+					enum adc_gain gain,
+					u8_t resolution,
+					s32_t *valp)
+{
+	s32_t adc_mv = *valp * ref_mv;
+	int ret = adc_gain_invert(gain, &adc_mv);
+
+	if (ret == 0) {
+		*valp = (adc_mv >> resolution);
+	}
+
+	return ret;
+}
 
 /* Forward declaration of the adc_sequence structure. */
 struct adc_sequence;