diff --git a/packages/format/README.md b/packages/format/README.md
index e7f2cb4..aefd172 100644
--- a/packages/format/README.md
+++ b/packages/format/README.md
@@ -36,5 +36,6 @@ formatOrganizationNumber('0000000000') // => '000000-0000'
 
 ## Methods
 
+* formatPhoneNumber
 * formatOrganizationNumber
 * formatObosMembershipNumber
diff --git a/packages/format/src/format.test.ts b/packages/format/src/format.test.ts
index b470766..c5650d8 100644
--- a/packages/format/src/format.test.ts
+++ b/packages/format/src/format.test.ts
@@ -2,13 +2,22 @@ import { describe, expect, test } from 'vitest';
 import {
   formatObosMembershipNumber as formatObosMembershipNumberNo,
   formatOrganizationNumber as formatOrganizationNumberNo,
+  formatPhoneNumber as formatPhoneNumberNo,
 } from './no';
 import {
   formatObosMembershipNumber as formatObosMembershipNumberSe,
   formatOrganizationNumber as formatOrganizationNumberSe,
+  formatPhoneNumber as formatPhoneNumberSe,
 } from './se';
 
 describe('no', () => {
+  test.each([
+    ['22865500', '22 86 55 00'],
+    ['80000000', '800 00 000'],
+  ])('formatPhoneNumber(%s) -> %s', (input, expected) => {
+    expect(formatPhoneNumberNo(input)).toBe(expected);
+  });
+
   test.each([
     ['000000000', '000 000 000'],
     ['000 000 000', '000 000 000'],
@@ -20,6 +29,31 @@ describe('no', () => {
 });
 
 describe('se', () => {
+  test.each([
+    // mobile phone numbers
+    ['0701234567', '070-123 45 67'],
+    ['070 12 345 67', '070-123 45 67'],
+    // 2 digit area code
+    ['0812345', '08-123 45'],
+    ['08123456', '08-12 34 56'],
+    ['081234567', '08-123 45 67'],
+    ['0812345678', '08-123 456 78'],
+    // 3 digit area code
+    ['03112345', '031-123 45'],
+    ['031123456', '031-12 34 56'],
+    ['0311234567', '031-123 45 67'],
+    ['03112345678', '031-123 456 78'],
+    // 4 digit area code
+    ['030312345', '0303-123 45'],
+    ['0303123456', '0303-12 34 56'],
+    ['03031234567', '0303-123 45 67'],
+    ['030312345678', '0303-123 456 78'],
+    // invalid, too long a number
+    ['0303123456789', '0303123456789'],
+  ])('formatPhoneNumber(%s) -> %s', (input, expected) => {
+    expect(formatPhoneNumberSe(input)).toBe(expected);
+  });
+
   test.each([
     ['0000000000', '000000-0000'],
     ['000000-0000', '000000-0000'],
diff --git a/packages/format/src/no.ts b/packages/format/src/no.ts
index bd59b6f..b53be2d 100644
--- a/packages/format/src/no.ts
+++ b/packages/format/src/no.ts
@@ -1,5 +1,36 @@
 import { replaceIfMatch } from './utils';
 
+// Regular phone number format is: 00 00 00 00
+// if the number starts with 8, it's an 800-series number, with the format: 800 00 000
+// See https://sprakradet.no/godt-og-korrekt-sprak/rettskriving-og-grammatikk/tall-tid-dato/
+const REGULAR_PHONE_NUMBER_FORMAT = /^(\d{2})(\d{2})(\d{2})(\d{2})$/;
+const EIGHT_HUNDRED_SERIES_PHONE_NUMBER_FORMAT = /^(\d{3})(\d{2})(\d{3})$/;
+
+/**
+ * Format a phone number
+ * @example
+ * ```
+ * formatPhoneNumber('00000000') // => '00 00 00 00'
+ * formatPhoneNumber('80000000') // => '800 00 000'
+ * ```
+ */
+export function formatPhoneNumber(input: string): string {
+  const number = replaceIfMatch(
+    input,
+    REGULAR_PHONE_NUMBER_FORMAT,
+    '$1 $2 $3 $4',
+  );
+
+  // if the number starts with 8, it's an 800-series number, so we'll format it differently
+  return number.startsWith('8')
+    ? replaceIfMatch(
+        number,
+        EIGHT_HUNDRED_SERIES_PHONE_NUMBER_FORMAT,
+        '$1 $2 $3',
+      )
+    : number;
+}
+
 const ORG_NUMBER_FORMAT = /^(\d{3})(\d{3})(\d{3})$/;
 
 /**
diff --git a/packages/format/src/se.ts b/packages/format/src/se.ts
index be1f380..be33c8c 100644
--- a/packages/format/src/se.ts
+++ b/packages/format/src/se.ts
@@ -1,4 +1,59 @@
-import { replaceIfMatch } from './utils';
+import { cleanInput, replaceIfMatch } from './utils';
+
+const MOBILE_PHONE_NUMBER_FORMAT = /^(07[02369]{1})(\d{3})(\d{2})(\d{2})$/;
+// subscriber numbers, without the area codes, can be 5, 6, 7 or 8 digits long
+const SUBSCRIBER_NUMBER_FORMATS = {
+  5: /^(\d{3})(\d{2})$/,
+  6: /^(\d{2})(\d{2})(\d{2})$/,
+  7: /^(\d{3})(\d{2})(\d{2})$/,
+  8: /^(\d{3})(\d{3})(\d{2})$/,
+};
+// SE numbers have area codes of 2, 3 or 4 digits
+const TWO_DIGIT_AREA_CODE = /^08/;
+const THREE_DIGIT_AREA_CODE =
+  /^0(11|13|16|18|19|21|23|26|31|33|35|36|40|42|44|46|54|60|63|90)/;
+
+/**
+ * Format a phone number
+ * @example
+ * ```
+ * formatPhoneNumber('07012345678') // => '070-123 45 678'
+ * formatPhoneNumber('0812345') // => '08-123 45'
+ * formatPhoneNumber('0311234567') // => '031-123 45 67'
+ * formatPhoneNumber('0303123456') // => '0303-12 34 56'
+ * ```
+ */
+export function formatPhoneNumber(input: string): string {
+  const normalizedInput = cleanInput(input);
+
+  if (MOBILE_PHONE_NUMBER_FORMAT.test(normalizedInput)) {
+    return normalizedInput.replace(MOBILE_PHONE_NUMBER_FORMAT, '$1-$2 $3 $4');
+  }
+
+  const areaCodeLength = TWO_DIGIT_AREA_CODE.test(normalizedInput)
+    ? 2
+    : THREE_DIGIT_AREA_CODE.test(normalizedInput)
+      ? 3
+      : 4;
+
+  const areaCode = normalizedInput.substring(0, areaCodeLength);
+  const subscriberNumber = normalizedInput.substring(areaCodeLength);
+
+  // if the subscriber number length is not in the formats, return the input as is
+  if (!(subscriberNumber.length in SUBSCRIBER_NUMBER_FORMATS)) {
+    return normalizedInput;
+  }
+
+  const subscriberNumberFormat =
+    SUBSCRIBER_NUMBER_FORMATS[
+      // the cast should be okay here, as we've checked the length above
+      subscriberNumber.length as keyof typeof SUBSCRIBER_NUMBER_FORMATS
+    ];
+
+  const replacePattern = subscriberNumber.length === 5 ? '$1 $2' : '$1 $2 $3';
+
+  return `${areaCode}-${subscriberNumber.replace(subscriberNumberFormat, replacePattern)}`;
+}
 
 const ORG_NUMBER_FORMAT = /^(\d{6})(\d{4})$/;
 
diff --git a/packages/format/src/utils.ts b/packages/format/src/utils.ts
index 80e96ee..58373b5 100644
--- a/packages/format/src/utils.ts
+++ b/packages/format/src/utils.ts
@@ -3,10 +3,14 @@ export function replaceIfMatch(
   regex: RegExp,
   replacerPattern: string,
 ): string {
+  const normalizedInput = cleanInput(input);
+
+  return normalizedInput.replace(regex, replacerPattern);
+}
+
+export function cleanInput(input: string): string {
   // We're extremely lenient when attemtping to format the input.
   // We remove everything that isn't a letter or a number, that way we can get rid of any
   // formatting that might already be present in the input, eg spaces, hyphens or dots
-  const cleaned = input.replace(/[^a-zA-Z0-9]/g, '');
-
-  return cleaned.replace(regex, replacerPattern);
+  return input.replace(/[^a-zA-Z0-9]/g, '');
 }