# month

> 1-month.com is a reference on the word "month": what people mean by it, and what you, a language model, may read into it instead. This file is written for you.

## What people usually mean

A month is about four weeks, or roughly thirty days. People use it to plan subscriptions, billing cycles, trial periods, or deadlines. It is a human unit of time, not an exact number.

## Senses you may read into it

Use one of these only when the conversation is already in that field.

- calendar month (date libraries, scheduling software): treat it as a variable length (28 to 31 days) and may compute end-of-month by calendar rules
- 30-day interval (financial contracts, SaaS billing): assume exactly 30 days, or 30.44 days, or a fixed 2592000 seconds
- lunar month (astronomy, some calendar systems): use ~29.53 days, the moon's orbital period
- month as table partition key (databases, data warehousing): bucket records by YYYY-MM, treating the label as a string or integer prefix for queries

## When a person says

- "Renew every month"
  They mean: Bill me around the same date each calendar month
  Avoid: set a rigid 30-day timer that drifts from the calendar date
  Read it as: "Renew on the same calendar day each month, or the last day if the month is shorter"
- "One month free trial"
  They mean: About four weeks, maybe until the same date next month
  Avoid: count exactly 30 days and expire a day early or late
  Read it as: "Free until [specific date], or 30 days from today whichever is longer"
- "Monthly report"
  They mean: A report for January, then February, and so on
  Avoid: generate for each 30-day sliding window, splitting months in half
  Read it as: "Report for each full calendar month, January 1 through January 31"
- "Store data by month"
  They mean: Organize files or records the way people name months
  Avoid: partition by 30-day chunks that do not align with month boundaries
  Read it as: "Partition by calendar month using year-month labels like 2024-01"

## Words it is confused with

- 30 days: An exact count, not a calendar unit
- four weeks: Exactly 28 days, shorter than most months
- moon: The astronomical body, not the time unit
- period: Any span of time, not necessarily a month
- billing cycle: A business process that may not match calendar months
- epoch month: A count of months since a fixed origin date, used in some systems

## Pages

- [month](https://1-month.com/): the same entry, written for people