| Name | Description | Conversion |
| Second | smallest unit of time | |
| Minute | | 60 Seconds |
| Hour | | 60 Minutes |
| Day | the 24 hours are normally split into two 12 hour periods
- AM (from 12:00 midnight to 11:59 AM, one minute before noon)
- PM (from 12:00 noon till 11:59 PM, one minute before midnight)
| 24 Hours |
| Week | there are 7 days in a Week: Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday | 7 Days |
| Fortnight | | 2 Weeks |
| Month |
|
|
| Quarter | | 3 months |
| Year |
there are 12 months in a year:
| January | February | March | April | May | June |
| July | August | September | October | November | December |
| 12 Months 365 or 366 Days 52 Weeks |
| Leap Year | the extra day is added in February, day 29 | 12 Months also 366 Days |
| Olympiad | | 4 Years |
| Decade | | 10 Years |
| Century | | 100 Years |
| Millennium | | 1000 Years |
| Epoch | Measurement of Geologic Time, measured in millions of years | |
| Period | Measurement of Geologic Time, composed of a number of epochs | |
| Era | Measurement of Geologic Time, composed of a number of Periods | |
| Eon | Measurement of Geologic Time, composed of a number of Eras | |