---
title: "measurements"
url: https://develop.sentry.dev/sdk/foundations/transport/event-payloads/properties/measurements/
---

# undefined

* `measurements`

  *Optional*. An object containing standard/custom measurements with keys signifying the name of the measurement.

- Standard measurement keys currently supported are from the following list taken from [here](https://github.com/getsentry/sentry/blob/a8c960a933d2ded5225841573d8fc426a482ca9c/static/app/utils/discover/fields.tsx#L654-L676).

```json
[
  // Web
  "fp",
  "fcp",
  "lcp",
  "fid",
  "cls",
  "ttfb",
  "ttfb.requesttime",

  // Mobile
  "app_start_cold",
  "app_start_warm",
  "frames_total",
  "frames_slow",
  "frames_frozen",

  // React native
  "frames_slow_rate",
  "frames_frozen_rate",
  "stall_count",
  "stall_total_time",
  "stall_longest_time",
  "stall_percentage"
]
```

* For the well-known measurements listed above, Sentry automatically infers units. Custom measurements need units to be specified; if the units are missing, Relay will set them to `"none"` as a default. The full list of supported units is specified on [Relay's `MetricUnit`](https://getsentry.github.io/relay/relay_metrics/enum.MetricUnit.html). Sentry's event ingestion supports arbitrary custom units, but many SDKs will not expose a generic user-defined unit interface.

```json
{
  "measurements": {
    "lcp": { "value": 100 },
    "fp": { "value": 123 },
    "my.custom.metric": { "value": 456, "unit": "millisecond" }
  }
}
```