diff --git a/include/trajopt/set/ConeSet2d.h b/include/trajopt/set/ConeSet2d.h
index 456decbe..a189b2ed 100644
--- a/include/trajopt/set/ConeSet2d.h
+++ b/include/trajopt/set/ConeSet2d.h
@@ -19,7 +19,7 @@ struct TRAJOPT_DLLEXPORT ConeSet2d {
   /**
    * Returns true if the set is valid.
    */
-  bool IsValid() const noexcept {
+  constexpr bool IsValid() const noexcept {
     return thetaBound.Range() > 0.0 && thetaBound.Range() <= std::numbers::pi;
   }
 };
diff --git a/include/trajopt/set/EllipticalSet2d.h b/include/trajopt/set/EllipticalSet2d.h
index 8e30d01c..10a09e00 100644
--- a/include/trajopt/set/EllipticalSet2d.h
+++ b/include/trajopt/set/EllipticalSet2d.h
@@ -39,7 +39,7 @@ struct TRAJOPT_DLLEXPORT EllipticalSet2d {
    * @param radius The radius.
    * @param direction The direction.
    */
-  static EllipticalSet2d CircularSet2d(
+  static constexpr EllipticalSet2d CircularSet2d(
       double radius, Direction direction = Direction::kInside) {
     return EllipticalSet2d{radius, radius, direction};
   }
@@ -47,12 +47,12 @@ struct TRAJOPT_DLLEXPORT EllipticalSet2d {
   /**
    * Returns true if the ellipse is a circle.
    */
-  bool IsCircular() const noexcept { return xRadius == yRadius; }
+  constexpr bool IsCircular() const noexcept { return xRadius == yRadius; }
 
   /**
    * Returns true if the set spans R².
    */
-  bool IsR2() const noexcept {
+  constexpr bool IsR2() const noexcept {
     return xRadius >= std::numeric_limits<double>::infinity() &&
            yRadius >= std::numeric_limits<double>::infinity();
   }
@@ -60,7 +60,9 @@ struct TRAJOPT_DLLEXPORT EllipticalSet2d {
   /**
    * Returns true if the set is valid.
    */
-  bool IsValid() const noexcept { return xRadius > 0.0 && yRadius > 0.0; }
+  constexpr bool IsValid() const noexcept {
+    return xRadius > 0.0 && yRadius > 0.0;
+  }
 };
 
 }  // namespace trajopt
diff --git a/include/trajopt/set/IntervalSet1d.h b/include/trajopt/set/IntervalSet1d.h
index 69d9303d..89385d59 100644
--- a/include/trajopt/set/IntervalSet1d.h
+++ b/include/trajopt/set/IntervalSet1d.h
@@ -25,21 +25,23 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    * @param lower The lower bound.
    * @param upper The upper bound.
    */
-  IntervalSet1d(double lower, double upper) : lower(lower), upper(upper) {}
+  constexpr IntervalSet1d(double lower, double upper)
+      : lower(lower), upper(upper) {}
 
   /**
    * Construct a Scalar Bound that represents the interval [value, value].
    *
    * @param value the value to bound the number between.
    */
-  IntervalSet1d(double value) : lower(value), upper(value) {}  // NOLINT
+  constexpr IntervalSet1d(double value)
+      : lower(value), upper(value) {}  // NOLINT
 
-  IntervalSet1d() = default;
+  constexpr IntervalSet1d() = default;
 
   /**
    * Returns an IntervalSet1d spanning R¹.
    */
-  static IntervalSet1d R1() {
+  static constexpr IntervalSet1d R1() {
     return IntervalSet1d(-std::numeric_limits<double>::infinity(),
                          +std::numeric_limits<double>::infinity());
   }
@@ -51,7 +53,7 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    * @param max the maximum value
    * @return [-∞, max]
    */
-  static IntervalSet1d LessThan(double max) {
+  static constexpr IntervalSet1d LessThan(double max) {
     return IntervalSet1d(-std::numeric_limits<double>::infinity(), max);
   }
 
@@ -62,7 +64,7 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    * @param min the minimum value
    * @return [min, ∞]
    */
-  static IntervalSet1d GreaterThan(double min) {
+  static constexpr IntervalSet1d GreaterThan(double min) {
     return IntervalSet1d(min, +std::numeric_limits<double>::infinity());
   }
 
@@ -75,7 +77,7 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    * @param other the other scalar bound
    * @return lower == other.lower && upper == other.upper
    */
-  bool operator==(const IntervalSet1d& other) const = default;
+  constexpr bool operator==(const IntervalSet1d& other) const = default;
 
   /**
    * Calculate the range of this scalar bound, which is the difference
@@ -84,7 +86,7 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    *
    * @return upper - lower
    */
-  double Range() const noexcept { return upper - lower; }
+  constexpr double Range() const noexcept { return upper - lower; }
 
   /**
    * Check if this scalar bound only contains one point. This only
@@ -92,7 +94,7 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    *
    * @return lower == upper
    */
-  bool IsExact() const noexcept { return lower == upper; }
+  constexpr bool IsExact() const noexcept { return lower == upper; }
 
   /**
    * Check if this scalar bound only contains 0. This occurs when
@@ -100,19 +102,21 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    *
    * @return lower == 0.0 && upper == 0.0
    */
-  bool IsZero() const noexcept { return lower == 0.0 && upper == 0.0; }
+  constexpr bool IsZero() const noexcept {
+    return lower == 0.0 && upper == 0.0;
+  }
 
   /**
    * Returns true if this IntervalSet1d has a lower bound.
    */
-  bool IsLowerBounded() const noexcept {
+  constexpr bool IsLowerBounded() const noexcept {
     return lower > -std::numeric_limits<double>::infinity();
   }
 
   /**
    * Returns true if this IntervalSet1d has an upper bound.
    */
-  bool IsUpperBounded() const noexcept {
+  constexpr bool IsUpperBounded() const noexcept {
     return upper < +std::numeric_limits<double>::infinity();
   }
 
@@ -123,7 +127,7 @@ struct TRAJOPT_DLLEXPORT IntervalSet1d {
    *
    * @return lower <= upper
    */
-  bool IsValid() const noexcept { return lower <= upper; }
+  constexpr bool IsValid() const noexcept { return lower <= upper; }
 };
 
 }  // namespace trajopt
diff --git a/include/trajopt/set/RectangularSet2d.h b/include/trajopt/set/RectangularSet2d.h
index 68fd9874..537e31bb 100644
--- a/include/trajopt/set/RectangularSet2d.h
+++ b/include/trajopt/set/RectangularSet2d.h
@@ -32,7 +32,7 @@ struct TRAJOPT_DLLEXPORT RectangularSet2d {
   /**
    * Construct a RectangularSet2d spanning R².
    */
-  static RectangularSet2d R2() {
+  static constexpr RectangularSet2d R2() {
     return RectangularSet2d{IntervalSet1d::R1(), IntervalSet1d::R1()};
   }
 
@@ -44,7 +44,9 @@ struct TRAJOPT_DLLEXPORT RectangularSet2d {
    *
    * @return true if and only if this planar bound is valid
    */
-  bool IsValid() const noexcept { return xBound.IsValid() && yBound.IsValid(); }
+  constexpr bool IsValid() const noexcept {
+    return xBound.IsValid() && yBound.IsValid();
+  }
 };
 
 }  // namespace trajopt