diff --git a/crates/coremem/src/meas.rs b/crates/coremem/src/meas.rs
index f097545..2690af6 100644
--- a/crates/coremem/src/meas.rs
+++ b/crates/coremem/src/meas.rs
@@ -2,12 +2,11 @@ use crate::geom::{Meters, Region, Torus, WorldRegion};
 use crate::real::{Real as _, ToFloat as _};
 use crate::cross::vec::Vec3;
 use crate::sim::AbstractSim;
-use indexmap::IndexMap;
 use serde::{Serialize, Deserialize};
 
 pub trait AbstractMeasurement<S>: Send + Sync {
     fn eval(&self, state: &S) -> String;
-    fn key_value(&self, state: &S) -> IndexMap<String, String>;
+    fn key_value(&self, state: &S) -> Vec<Measurement>;
 }
 
 pub fn as_dyn_measurements<S, M: AbstractMeasurement<S>>(meas: &[M]) -> Vec<&dyn AbstractMeasurement<S>> {
@@ -15,20 +14,59 @@ pub fn as_dyn_measurements<S, M: AbstractMeasurement<S>>(meas: &[M]) -> Vec<&dyn
 }
 
 
-/// create one IndexMap out of several measurements
-pub fn eval_multiple_kv<S>(state: &S, meas: &[&dyn AbstractMeasurement<S>]) -> IndexMap<String, String> {
-    let mut r = IndexMap::new();
-    for m in meas {
-        let other = m.key_value(state);
-        r.extend(other.into_iter());
-    }
-    r
+/// combine several measurements
+pub fn eval_multiple_kv<S>(state: &S, meas: &[&dyn AbstractMeasurement<S>]) -> Vec<Measurement>
+    meas.into_iter().flat_map(|m| m.key_value(state).into_iter()).collect()
 }
 
-pub fn eval_to_vec<S>(state: &S, meas: &[&dyn AbstractMeasurement<S>]) -> Vec<Evaluated> {
-    eval_multiple_kv(state, meas).into_iter().map(|(k, v)| {
-        Evaluated::new(k, v)
-    }).collect()
+#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize)]
+pub enum MeasurementValue {
+    Field(Vec3<f32>),
+    Float(f32),
+    Int(u64),
+    Dim(Vec3u),
+}
+
+impl From<Vec3<f32>> for MeasurementValue {
+    fn from(v: Vec3<f32>) -> Self {
+        Self::Field(v)
+    }
+}
+impl From<f32> for MeasurementValue {
+    fn from(v: f32) -> Self {
+        Self::Float(v)
+    }
+}
+impl From<u64> for MeasurementValue {
+    fn from(v: u64) -> Self {
+        Self::Int(v)
+    }
+}
+impl From<Vec3u> for MeasurementValue {
+    fn from(v: Vec3u) -> Self {
+        Self::Dim(v)
+    }
+}
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize)]
+pub struct Measurement {
+    name: String,
+    value: MeasurementValue,
+    /// e.g. "A" for Amps
+    unit: String,
+}
+
+impl Measurement {
+    fn new<T: Into<MeasurementValue>>(name: &str, value: T, unit: &str) -> Self {
+        Self {
+            name.to_owned(),
+            value: value.into(),
+            unit: unit.to_owned(),
+        }
+    }
+    fn new_unitless<T: Into<MeasurementValue>>(name: &str, value: T) -> Self {
+        Self::new(name, value, "")
+    }
 }
 
 enum SiScale {
@@ -111,11 +149,11 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Time {
     fn eval(&self, state: &S) -> String {
         format!("{} (step {})", SiScale::format_short(state.time(), "s"), state.step_no())
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
-        [
-            ("step".to_string(), state.step_no().to_string()),
-            ("time".to_string(), state.time().to_string()),
-        ].into_iter().collect()
+    fn key_value(&self, state: &S) -> Vec<Measurement>
+        vec![
+            Measurement::new_unitless("step", state.step_no()),
+            Measurement::new("time", state.time(), "s"),
+        ]
     }
 }
 
@@ -126,42 +164,11 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Meta {
     fn eval(&self, state: &S) -> String {
         format!("{}x{}x{} feat: {:.1e}m", state.width(), state.height(), state.depth(), state.feature_size())
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
-        [
-            ("width".to_string(), state.width().to_string()),
-            ("height".to_string(), state.height().to_string()),
-            ("depth".to_string(), state.depth().to_string()),
-            ("feature_size".to_string(), state.feature_size().to_string()),
-        ].into_iter().collect()
-    }
-}
-
-/// some measurement which has already been evaluated.
-/// this is used particularly if we need to monomorphize a measurement (e.g. for serialization)
-/// and know it won't be applied to a new/different state.
-#[derive(Clone, Serialize, Deserialize)]
-pub struct Evaluated(String, String);
-
-impl Evaluated {
-    pub fn new<S1: Into<String>, S2: Into<String>>(key: S1, value: S2) -> Self {
-        Self(key.into(), value.into())
-    }
-    pub fn key(&self) -> &str {
-        &*self.0
-    }
-    pub fn value(&self) -> &str {
-        &*self.1
-    }
-}
-
-impl<S> AbstractMeasurement<S> for Evaluated {
-    fn eval(&self, _state: &S) -> String {
-        format!("{}: {}", self.0, self.1)
-    }
-    fn key_value(&self, _state: &S) -> IndexMap<String, String> {
-        [
-            (self.0.clone(), self.1.clone()),
-        ].into_iter().collect()
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
+        vec![
+            Measurement::new_unitless("dim", state.dim()),
+            Measurement::new("feature_size", state.feature_size(), "m"),
+        ]
     }
 }
 
@@ -193,10 +200,10 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Volume {
             self.data(state),
         )
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
-        [
-            (format!("Vol({})", self.name), self.data(state).to_string()),
-        ].into_iter().collect()
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
+        vec![
+            Measurement::new(&format!("Vol({})", self.name), self.data(), "um^3"),
+        ]
     }
 }
 
@@ -277,12 +284,20 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Current {
             mean_current_mag,
             mean_current_vec)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let (mean_current_mag, mean_current_vec) = self.data(state);
-        [
-            (format!("Imag/cell({})", self.name), mean_current_mag.to_string()),
-            (format!("I/cell({})", self.name), mean_current_vec.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new(
+                &format!("Imag/cell({})", self.name),
+                mean_current_mag,
+                "A",
+            ),
+            Measurement::new(
+                &format!("/cell({})", self.name),
+                mean_current_vec,
+                "A",
+            ),
+        ]
     }
 }
 
@@ -321,11 +336,15 @@ impl<S: AbstractSim> AbstractMeasurement<S> for CurrentLoop {
         let cross_sectional_current = self.data(state);
         format!("I({}): {:.2e}", self.name, cross_sectional_current)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let cross_sectional_current = self.data(state);
-        [
-            (format!("I({})", self.name), cross_sectional_current.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new(
+                &format!("I({})", self.name),
+                cross_sectional_current,
+                "A"
+            ),
+        ]
     }
 }
 
@@ -394,13 +413,13 @@ impl<S: AbstractSim> AbstractMeasurement<S> for MagneticLoop {
             self.name, mean_directed_h,
         )
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let (mean_directed_m, mean_directed_b, mean_directed_h) = self.data(state);
-        [
-            (format!("M({})", self.name), mean_directed_m.to_string()),
-            (format!("B({})", self.name), mean_directed_b.to_string()),
-            (format!("H({})", self.name), mean_directed_h.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(&format!("M({})", self.name), mean_directed_current_m),
+            Beasurement::new_unitless(&format!("B({})", self.name), mean_directed_current_b),
+            Beasurement::new_unitless(&format!("H({})", self.name), mean_directed_current_h),
+        ]
     }
 }
 
@@ -434,11 +453,14 @@ impl<S: AbstractSim> AbstractMeasurement<S> for MagneticFlux {
         let mean_mag = self.data(state);
         format!("Bavg({}): {:.2e}", self.name, mean_mag)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let mean_mag = self.data(state);
-        [
-            (format!("Bavg({})", self.name), mean_mag.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(
+                &format!("Bavg({})", self.name),
+                mean_mag,
+            )
+        ]
     }
 }
 
@@ -472,11 +494,13 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Magnetization {
         let mean_mag = self.data(state);
         format!("Mavg({}): {:.2e}", self.name, mean_mag)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let mean_mag = self.data(state);
-        [
-            (format!("Mavg({})", self.name), mean_mag.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(
+                &format!("Mavg({})", self.name), mean_mag
+            ),
+        ]
     }
 }
 
@@ -493,11 +517,11 @@ impl<S: AbstractSim> AbstractMeasurement<S> for MagnetizationAt {
         let m = state.sample(self.0).m();
         format!("M{}: {:.2e}", loc(self.0), m)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let m = state.sample(self.0).m();
-        [
-            (format!("M{}", loc(self.0)), m.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(&format!("M{}", loc(self.0)), m)
+        ]
     }
 }
 
@@ -510,11 +534,13 @@ impl<S: AbstractSim> AbstractMeasurement<S> for MagneticFluxAt {
         let b = state.sample(self.0).b();
         format!("B{}: {:.2e}", loc(self.0), b)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let b = state.sample(self.0).b();
-        [
-            (format!("B{}", loc(self.0)), b.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(
+                &format!("B{}", loc(self.0)), b
+            )
+        ]
     }
 }
 
@@ -527,11 +553,13 @@ impl<S: AbstractSim> AbstractMeasurement<S> for MagneticStrengthAt {
         let h = state.sample(self.0).h();
         format!("H{}: {:.2e}", loc(self.0), h)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let h = state.sample(self.0).h();
-        [
-            (format!("H{}", loc(self.0)), h.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(
+                &format!("H{}", loc(self.0)), h
+            )
+        ]
     }
 }
 
@@ -543,11 +571,13 @@ impl<S: AbstractSim> AbstractMeasurement<S> for ElectricField {
         let e = state.sample(self.0).e();
         format!("E{}: {}", loc(self.0), e)
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let e = state.sample(self.0).e();
-        [
-            (format!("E{}", loc(self.0)), e.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(
+                &format!("E{}", loc(self.0)), e
+            )
+        ]
     }
 }
 
@@ -589,11 +619,13 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Energy {
         let e = self.data(state);
         format!("U({}): {}", self.name, SiScale::format_short(e, "J"))
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let e = self.data(state);
-        [
-            (format!("U({})", self.name), e.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new_unitless(
+                &format!("U({})", self.name), e
+            )
+        ]
     }
 }
 
@@ -630,10 +662,12 @@ impl<S: AbstractSim> AbstractMeasurement<S> for Power {
         let power = self.data(state);
         format!("P({}): {}", self.name, SiScale::format_short(power, "W"))
     }
-    fn key_value(&self, state: &S) -> IndexMap<String, String> {
+    fn key_value(&self, state: &S) -> Vec<Measurement> {
         let power = self.data(state);
-        [
-            (format!("P({})", self.name), power.to_string()),
-        ].into_iter().collect()
+        vec![
+            Measurement::new(
+                &format!("P({})", self.name), power, "W"
+            )
+        ]
     }
 }