---
title: time_delta() | Tiger Data Docs
description: Calculate the difference between the first and last times from a gauge aggregate
---

Early access [1.6.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.6.0)

Get the number of seconds between the first and last measurements in a gauge aggregate

## Samples

Get the time difference between the first and last gauge readings for each 15-minute interval. Note this difference isn’t necessarily equal to `15 minutes * 60 seconds / minute`, because the first and last readings might not fall exactly on the interval boundaries.

```
SELECT
    id,
    bucket,
    time_delta(summary)
FROM (
    SELECT
        id,
        time_bucket('15 min'::interval, ts) AS bucket,
        gauge_agg(ts, val) AS summary
    FROM foo
    GROUP BY id, time_bucket('15 min'::interval, ts)
) t
```

## Arguments

The syntax is:

```
time_delta(
    summary GaugeSummary
) RETURNS DOUBLE PRECISION
```

| Name      | Type           | Default | Required | Description                                                                                                             |
| --------- | -------------- | ------- | -------- | ----------------------------------------------------------------------------------------------------------------------- |
| `summary` | `GaugeSummary` | -       | ✔        | A gauge aggregate created using [`gauge_agg`](/docs/reference/toolkit/counters-and-gauges/gauge_agg/gauge_agg/index.md) |

## Returns

| Column      | Type             | Description                                                  |
| ----------- | ---------------- | ------------------------------------------------------------ |
| time\_delta | DOUBLE PRECISION | The difference, in seconds, between the first and last times |