---
title: "Calculations"
description: "Age, days and months between dates, matching days, weeks and lists of years"
type: "docs"
category: "doc"
tags: []
authors: [Anonymous]
date: "2026-11-05"
last_update: "2026-11-05"
time_minutes: 2
draft: false
unlisted: false
url: "https://www.derafu.dev/docs/core/date/calculations"
---

# Calculations

```php
use Derafu\Date\Support\DateCalculator;
```

What depends on the current date takes a [clock](clocks) as its last argument, and uses the clock of the system if it is not given one. The dates are `DateTimeInterface` objects or texts.

| Method | What it gives |
| --- | --- |
| `DateCalculator::age($birth, $clock = null)` | The age in years. |
| `DateCalculator::daysBetween($from, $to = null, $clock = null)` | The complete days from a date to another one (negative if the second is before). Without `$to`, until the clock. |
| `DateCalculator::monthsBetween($from, $to = null, $clock = null)` | The months between the months of two dates, without looking at the days. A period written as `202511` is accepted instead of a date. |
| `DateCalculator::countMatchingDays($from, $to, $days, $excludeWeekend = false)` | How many days of a range are in a list of `Y-m-d` dates. |
| `DateCalculator::firstDayOfWeek($date = null, $clock = null)` | Monday of the week, at the start of the day. |
| `DateCalculator::lastDayOfWeek($date = null, $clock = null)` | Sunday of the week, at the end of the day. |
| `DateCalculator::years($total, $from = null, $clock = null)` | A list of years, from the most recent to the oldest. |

```php
DateCalculator::monthsBetween(202301, '2024-01-15');   // 12
DateCalculator::monthsBetween('2024-01-15', '2024-02-14');   // 1
DateCalculator::years(3, 2024);   // [2024, 2023, 2022]
```



---
Last updated on 05/11/2026