SQL Server: For every 3 unique ids group together and set groupid without using CASE Expression

Table table_name

Following SQL will give me the answer Demo but I need to hardcode each case and I need to know the MAX(id) in the first place.

SELECT id,
CASE 
WHEN id > '0' AND id <= '3' THEN 1 
WHEN id > '3' AND id <= '6' THEN 2 
WHEN id > '6' AND id <= '9' THEN 3 
WHEN id > '9' AND id <= '12' THEN 4
END AS groupid
FROM table_name

How to improve it without me hardcode using the CASE. Since id column will continue increasing and it will runout of case sometime later.

(SQL Server 2014 – build v12.0.6108.1)

Result:

>Solution :

SELECT id, CEILING(id/3.0) AS groupid
FROM table_name