This is today's date on the regular (Gregorian) calendar:

Saturday
26
July
2025
Sunday
27
July
2025
Monday
28
July
2025
Tuesday
29
July
2025
Wednesday
30
July
2025
Today
Thursday
31
July
2025
Friday
1
August
2025
Saturday
2
August
2025
Sunday
3
August
2025
Monday
4
August
2025
Tuesday
5
August
2025

…and this is the same date on the World calendar:

Thursday
26
July
2025
Friday
27
July
2025
Saturday
28
July
2025
Sunday
29
July
2025
Monday
30
July
2025
Today
Tuesday
31
July
2025
Wednesday
1
August
2025
Thursday
2
August
2025
Friday
3
August
2025
Saturday
4
August
2025
Sunday
5
August
2025

…and on the International fixed calendar:

Thursday
12
July
2025
Friday
13
July
2025
Saturday
14
July
2025
Sunday
15
July
2025
Monday
16
July
2025
Today
Tuesday
17
July
2025
Wednesday
18
July
2025
Thursday
19
July
2025
Friday
20
July
2025
Saturday
21
July
2025
Sunday
22
July
2025

What about a decimal calendar?

Decimal calendars have been attempted, but none have gathered much interest. Some had 10 months of ~36 days, some kept the 12 months, but divided them into 3 weeks of 10 days where the 5 or 6 extra days (to match a solar year) happen after the last month.