diff --git a/README.md b/README.md
index 96906ab..aa13e77 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ A central class in Nifty ToU is [TemporalRangesTariff](./docs/md/nifty-tou.tempo
 that defines a set of tariff values with a set of time-based constraints. The implication is that the
 tariff values apply only when all the time-based constraints are valid.
 
-The time-based constraints are encoded as [IntRange](docs/md/nifty-tou.intrange.md) objects,
+The time-based constraints are encoded as [IntRange](./docs/md/nifty-tou.intrange.md) objects,
 that are integer ranges with minimum and maximum values that define the bounds of the constraint.
 The supported time-based constraints are:
 
@@ -207,6 +207,26 @@ new TariffRate("Morning Fixed", 125, -2);
 new TariffRate("Morning Variable", 1, -1);
 ```
 
+# Chronological tariffs
+
+The [ChronoTariff](./docs/md/nifty-tou.chronotariff.md) class can be used to model a time-based
+"fixed" tariff, such as a daily or monthly charge. For example:
+
+```ts
+// construct a chronological tariff @ 10/day
+const tariff = new ChronoTariff(ChronoTariffUnit.DAYS, 10);
+
+// calculate the tariff cost over a 7 day time range
+const cost =
+	tariff.rate *
+	tariff.quantity(
+		new Date("2024-01-01T00:00:00Z"),
+		new Date("2024-01-08T00:00:00Z"),
+		true
+	);
+cost === 70; // 7 days @ 10/day
+```
+
 # Language support
 
 Nifty ToU supports parsing and formatting text-based range values, in different languages. For
diff --git a/dist/nifty-tou.d.ts b/dist/nifty-tou.d.ts
index 1d2b040..a63ed12 100644
--- a/dist/nifty-tou.d.ts
+++ b/dist/nifty-tou.d.ts
@@ -157,6 +157,61 @@ export declare class ChronoFieldValue {
     get rangeValue(): number | null;
 }
 
+/**
+ * A chronologically-based tariff, such as a "daily" charge.
+ * @public
+ */
+export declare class ChronoTariff {
+    #private;
+    /**
+     * Constructor.
+     *
+     * @param chronoUnit - the chrono unit
+     * @param rate - the rate per chrono unit
+     * @param name - an optional description
+     */
+    constructor(chronoUnit: ChronoTariffUnit, rate: number, name?: string);
+    /** Get the unit. */
+    get unit(): ChronoTariffUnit;
+    /** Get the rate. */
+    get rate(): number;
+    /** Get the optional name. */
+    get name(): string | undefined;
+    /**
+     * Calcualte the count of units between two dates.
+     *
+     * The cost of this tariff can be calculated by multiplying the `rate` by the result
+     * of this method, for example:
+     *
+     * ```ts
+     * const tariff = new ChronoTariff(ChronoTariffUnit.DAYS, 10);
+     * tariff.rate * tariff.quantity(
+     *     new Date('2024-01-01T00:00:00Z'),
+     *     new Date('2024-01-08T00:00:00Z'),
+     *     true) === 70; // 7 days @ 10/day
+     * ```
+     *
+     * @param from - the starting date
+     * @param to - the ending date (exclusive)
+     * @param utc - if `true` then use UTC date components, otherwise assume the local time zone
+     * @returns the count of units between `from` and `to`, including any fractional component
+     */
+    quantity(from: Date, to: Date, utc?: boolean): number;
+}
+
+/**
+ * An enumeration of supported chronological tariff units of the Gregorian calendar.
+ * @public
+ */
+export declare enum ChronoTariffUnit {
+    /** Days */
+    DAYS = 0,
+    /** Weeks */
+    WEEKS = 1,
+    /** Months */
+    MONTHS = 2
+}
+
 /**
  * API for a comparison between similar objects.
  * @public
diff --git a/docs/md/nifty-tou.chronotariff._constructor_.md b/docs/md/nifty-tou.chronotariff._constructor_.md
new file mode 100644
index 0000000..786fb4e
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariff._constructor_.md
@@ -0,0 +1,22 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariff](./nifty-tou.chronotariff.md) &gt; [(constructor)](./nifty-tou.chronotariff._constructor_.md)
+
+## ChronoTariff.(constructor)
+
+Constructor.
+
+**Signature:**
+
+```typescript
+constructor(chronoUnit: ChronoTariffUnit, rate: number, name?: string);
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  chronoUnit | [ChronoTariffUnit](./nifty-tou.chronotariffunit.md) | the chrono unit |
+|  rate | number | the rate per chrono unit |
+|  name | string | _(Optional)_ an optional description |
+
diff --git a/docs/md/nifty-tou.chronotariff.md b/docs/md/nifty-tou.chronotariff.md
new file mode 100644
index 0000000..aa00ae3
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariff.md
@@ -0,0 +1,42 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariff](./nifty-tou.chronotariff.md)
+
+## ChronoTariff class
+
+A chronologically-based tariff, such as a "daily" charge.
+
+**Signature:**
+
+```typescript
+export default class ChronoTariff 
+```
+
+## Constructors
+
+|  Constructor | Modifiers | Description |
+|  --- | --- | --- |
+|  [(constructor)(chronoUnit, rate, name)](./nifty-tou.chronotariff._constructor_.md) |  | Constructor. |
+
+## Properties
+
+|  Property | Modifiers | Type | Description |
+|  --- | --- | --- | --- |
+|  [name](./nifty-tou.chronotariff.name.md) | <code>readonly</code> | string \| undefined | Get the optional name. |
+|  [rate](./nifty-tou.chronotariff.rate.md) | <code>readonly</code> | number | Get the rate. |
+|  [unit](./nifty-tou.chronotariff.unit.md) | <code>readonly</code> | [ChronoTariffUnit](./nifty-tou.chronotariffunit.md) | Get the unit. |
+
+## Methods
+
+|  Method | Modifiers | Description |
+|  --- | --- | --- |
+|  [quantity(from, to, utc)](./nifty-tou.chronotariff.quantity.md) |  | <p>Calcualte the count of units between two dates.</p><p>The cost of this tariff can be calculated by multiplying the <code>rate</code> by the result of this method, for example:</p>
+```ts
+const tariff = new ChronoTariff(ChronoTariffUnit.DAYS, 10);
+tariff.rate * tariff.quantity(
+    new Date('2024-01-01T00:00:00Z'),
+    new Date('2024-01-08T00:00:00Z'),
+    true) === 70; // 7 days @ 10/day
+```
+ |
+
diff --git a/docs/md/nifty-tou.chronotariff.name.md b/docs/md/nifty-tou.chronotariff.name.md
new file mode 100644
index 0000000..ce81483
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariff.name.md
@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariff](./nifty-tou.chronotariff.md) &gt; [name](./nifty-tou.chronotariff.name.md)
+
+## ChronoTariff.name property
+
+Get the optional name.
+
+**Signature:**
+
+```typescript
+get name(): string | undefined;
+```
diff --git a/docs/md/nifty-tou.chronotariff.quantity.md b/docs/md/nifty-tou.chronotariff.quantity.md
new file mode 100644
index 0000000..d6d1555
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariff.quantity.md
@@ -0,0 +1,38 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariff](./nifty-tou.chronotariff.md) &gt; [quantity](./nifty-tou.chronotariff.quantity.md)
+
+## ChronoTariff.quantity() method
+
+Calcualte the count of units between two dates.
+
+The cost of this tariff can be calculated by multiplying the `rate` by the result of this method, for example:
+
+```ts
+const tariff = new ChronoTariff(ChronoTariffUnit.DAYS, 10);
+tariff.rate * tariff.quantity(
+    new Date('2024-01-01T00:00:00Z'),
+    new Date('2024-01-08T00:00:00Z'),
+    true) === 70; // 7 days @ 10/day
+```
+
+**Signature:**
+
+```typescript
+quantity(from: Date, to: Date, utc?: boolean): number;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  from | Date | the starting date |
+|  to | Date | the ending date (exclusive) |
+|  utc | boolean | _(Optional)_ if <code>true</code> then use UTC date components, otherwise assume the local time zone |
+
+**Returns:**
+
+number
+
+the count of units between `from` and `to`<!-- -->, including any fractional component
+
diff --git a/docs/md/nifty-tou.chronotariff.rate.md b/docs/md/nifty-tou.chronotariff.rate.md
new file mode 100644
index 0000000..8ba193a
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariff.rate.md
@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariff](./nifty-tou.chronotariff.md) &gt; [rate](./nifty-tou.chronotariff.rate.md)
+
+## ChronoTariff.rate property
+
+Get the rate.
+
+**Signature:**
+
+```typescript
+get rate(): number;
+```
diff --git a/docs/md/nifty-tou.chronotariff.unit.md b/docs/md/nifty-tou.chronotariff.unit.md
new file mode 100644
index 0000000..0e94ae7
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariff.unit.md
@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariff](./nifty-tou.chronotariff.md) &gt; [unit](./nifty-tou.chronotariff.unit.md)
+
+## ChronoTariff.unit property
+
+Get the unit.
+
+**Signature:**
+
+```typescript
+get unit(): ChronoTariffUnit;
+```
diff --git a/docs/md/nifty-tou.chronotariffunit.md b/docs/md/nifty-tou.chronotariffunit.md
new file mode 100644
index 0000000..c56a3eb
--- /dev/null
+++ b/docs/md/nifty-tou.chronotariffunit.md
@@ -0,0 +1,22 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [nifty-tou](./nifty-tou.md) &gt; [ChronoTariffUnit](./nifty-tou.chronotariffunit.md)
+
+## ChronoTariffUnit enum
+
+An enumeration of supported chronological tariff units of the Gregorian calendar.
+
+**Signature:**
+
+```typescript
+export declare enum ChronoTariffUnit 
+```
+
+## Enumeration Members
+
+|  Member | Value | Description |
+|  --- | --- | --- |
+|  DAYS | <code>0</code> | Days |
+|  MONTHS | <code>2</code> | Months |
+|  WEEKS | <code>1</code> | Weeks |
+
diff --git a/docs/md/nifty-tou.md b/docs/md/nifty-tou.md
index 1200540..5505c4d 100644
--- a/docs/md/nifty-tou.md
+++ b/docs/md/nifty-tou.md
@@ -12,6 +12,7 @@ A delightful little library for working with time-of-use tariffs.
 |  --- | --- |
 |  [ChronoFieldFormatter](./nifty-tou.chronofieldformatter.md) | Class to parse locale-specific chronological field names of the Gregorian calendar. |
 |  [ChronoFieldValue](./nifty-tou.chronofieldvalue.md) | A chronological field value. |
+|  [ChronoTariff](./nifty-tou.chronotariff.md) | A chronologically-based tariff, such as a "daily" charge. |
 |  [IntRange](./nifty-tou.intrange.md) | An immutable number range with min/max values. |
 |  [NumberFormatter](./nifty-tou.numberformatter.md) | A locale-specific number parser. |
 |  [TariffRate](./nifty-tou.tariffrate.md) | An identifiable tariff rate. |
@@ -25,6 +26,7 @@ A delightful little library for working with time-of-use tariffs.
 |  Enumeration | Description |
 |  --- | --- |
 |  [ChronoField](./nifty-tou.chronofield.md) | An enumeration of supported chronological fields of the Gregorian calendar. |
+|  [ChronoTariffUnit](./nifty-tou.chronotariffunit.md) | An enumeration of supported chronological tariff units of the Gregorian calendar. |
 
 ## Interfaces
 
diff --git a/etc/nifty-tou.api.md b/etc/nifty-tou.api.md
index 29cf53a..4bdf777 100644
--- a/etc/nifty-tou.api.md
+++ b/etc/nifty-tou.api.md
@@ -40,6 +40,22 @@ export class ChronoFieldValue {
     get value(): number;
 }
 
+// @public
+export class ChronoTariff {
+    constructor(chronoUnit: ChronoTariffUnit, rate: number, name?: string);
+    get name(): string | undefined;
+    quantity(from: Date, to: Date, utc?: boolean): number;
+    get rate(): number;
+    get unit(): ChronoTariffUnit;
+}
+
+// @public
+export enum ChronoTariffUnit {
+    DAYS = 0,
+    MONTHS = 2,
+    WEEKS = 1
+}
+
 // @public
 export interface Comparable<T> {
     compareTo(o: T | undefined): number;