---
title: "DATEDIFF(): How to Calculate the Time Difference Between Two Dates?"
description: "Follow these steps to compute a date difference (e.g., age, duration, delay): Step 1: Create the variable Click “+ New variable” Enter a name (e.g., Age…"
---

[Skip to content](https://help.easymedstat.com/support/solutions/articles/77000570852-datediff-how-to-calculate-the-time-difference-between-two-dates-#main-content)

English

Show submenu for translations

![](https://help.easymedstat.com/hs-fs/hubfs/Logo%20EMS%20HQ%20Noir-1.png?width=366&height=70&name=Logo%20EMS%20HQ%20Noir-1.png)

Open main navigation

Close main navigation

- English
  
  Show submenu for translations
- [Open a ticket](https://t3jiy.share-eu1.hsforms.com/2pRawwxfuSS6Scx4Qn4KSPA)

[Open a ticket](https://t3jiy.share-eu1.hsforms.com/2pRawwxfuSS6Scx4Qn4KSPA)

 How can we help you?

- There are no suggestions because the search field is empty.

1. [EasyMedStat Knowledge Base](https://help.easymedstat.com/?hsLang=en)
2. [Variables](https://help.easymedstat.com/variables?hsLang=en)
3. [Dynamic Variables](https://help.easymedstat.com/variables?hsLang=en#dynamic-variables)

# DATEDIFF(): How to Calculate the Time Difference Between Two Dates?

Follow these steps to compute a date difference (e.g., age, duration, delay):

### Step 1: Create the variable

- Click “+ New variable”
- Enter a name (e.g., Age at inclusion)
- Set the type to Numeric  
  A date difference always returns a number

### Step 2: Add a formula

- In the “Dynamic variable” panel, click “Add formula”

### Step 3: Use the Date difference helper

- In the left panel, click “Date difference”
- Select the unit you want (day, month, year, etc.)
- A formula is automatically inserted:

```
datediff(start_date, end_date, "unit")
```

### ![](https://help.easymedstat.com/hubfs/Base%20de%20connaissances/vJWZQnC1HSug8wsoJPyUoce13ypOvjhLpg.png)

### Step 4: Replace the variables

- Replace `start_date` with your earlier date (e.g., Birth\_date)
- Replace `end_date` with your later date (e.g., Inclusion\_date)

### Example: Age at inclusion

```
datediff(Birth_date, Inclusion_date, "year")
```

This calculates the patient’s age in years at the time of inclusion.

### Step 5: Confirm

- Check the “Variable mapping” if needed (usually not needed)
- Click “Confirm” to save the formula

- [Account](https://help.easymedstat.com/account?hsLang=en#main-content)

    - [Account](https://help.easymedstat.com/account?hsLang=en#account)
- [Collect data](https://help.easymedstat.com/collect-data?hsLang=en#main-content)

    - [Questionnaires (ePRO)](https://help.easymedstat.com/collect-data?hsLang=en#questionnaires-epro)
    - [Add and edit patients](https://help.easymedstat.com/collect-data?hsLang=en#add-and-edit-patients)
    - [Randomization](https://help.easymedstat.com/collect-data?hsLang=en#randomization)
    - [Export](https://help.easymedstat.com/collect-data?hsLang=en#export)
    - [Create a series / eCRF](https://help.easymedstat.com/collect-data?hsLang=en#create-a-series-ecrf)
    - [Multilingual studies](https://help.easymedstat.com/collect-data?hsLang=en#multilingual-studies)
- [Variables](https://help.easymedstat.com/variables?hsLang=en#main-content)

    - [Organize in categories](https://help.easymedstat.com/variables?hsLang=en#organize-in-categories)
    - [Dynamic Variables](https://help.easymedstat.com/variables?hsLang=en#dynamic-variables)
    - [Manage variables](https://help.easymedstat.com/variables?hsLang=en#manage-variables)
- [Statistical analyses](https://help.easymedstat.com/statistical-analyses?hsLang=en#main-content)

    - [Statistical tests](https://help.easymedstat.com/statistical-analyses?hsLang=en#statistical-tests)
    - [Compare groups](https://help.easymedstat.com/statistical-analyses?hsLang=en#compare-groups)
    - [Multivariate analysis](https://help.easymedstat.com/statistical-analyses?hsLang=en#multivariate-analysis)
    - [Filter patients](https://help.easymedstat.com/statistical-analyses?hsLang=en#filter-patients)
    - [Descriptive Statistics](https://help.easymedstat.com/statistical-analyses?hsLang=en#descriptive-statistics)
- [Collaborate](https://help.easymedstat.com/collaborate?hsLang=en#main-content)

    - [Share your series](https://help.easymedstat.com/collaborate?hsLang=en#share-your-series)
    - [Manage your organization](https://help.easymedstat.com/collaborate?hsLang=en#manage-your-organization)
- [Monitoring](https://help.easymedstat.com/monitoring?hsLang=en#main-content)

    - [Automations](https://help.easymedstat.com/monitoring?hsLang=en#automations)
    - [Electronic Signatures](https://help.easymedstat.com/monitoring?hsLang=en#electronic-signatures)
    - [Queries](https://help.easymedstat.com/monitoring?hsLang=en#queries)
    - [Clean data](https://help.easymedstat.com/monitoring?hsLang=en#clean-data)

[![](https://help.easymedstat.com/hs-fs/hubfs/Logo%20EMS%20HQ%20Noir-1.png?width=366&height=70&name=Logo%20EMS%20HQ%20Noir-1.png)](http://www.easymedstat.com)

<https://www.linkedin.com/company/easymedstat/> <https://www.youtube.com/@easymedstat9719> [mailto:support@easymedstat.com](mailto:support@easymedstat.com)

Copyright © 2026, EasyMedStat