# What is conversion lag?

> Conversion lag is the gap between an ad click and the sale. It makes recent days look worse than they will end up. How to read it, with a rupee example.
- **Author**: Marxx
- **Published**: 2026-11-14
- **Category**: Measurement
- **URL**: https://marxx.ai/library-glossary/conversion-lag

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Conversion lag is the time between someone clicking your ad and completing a sale or sign-up. Because buyers take time, your most recent days look worse than they will finally be. Google says this can make CPA look higher and ROAS look lower than they will end up ([Google Ads Help](https://support.google.com/google-ads/answer/9347141), checked 2026-10-20).

## Why it happens

Google Ads credits a conversion to the day of the click, not the day of the sale ([Google](https://support.google.com/google-ads/answer/6270625)). A click on Monday that buys on Friday is added to Monday. So Monday's numbers keep rising for days. Google lets you set the conversion window from 1 to 90 days, depending on the conversion source ([Google Ads Help](https://support.google.com/google-ads/answer/3123169)). So a sale can land up to 90 days after the click.

## A worked example

Say you spend INR 10,000 on Monday. Over time, the purchases from Monday's clicks add up. The numbers are made up.

| When you look | Purchases credited to Monday | Cost per purchase |
|---|---|---|
| Monday night | 12 | INR 833 |
| Wednesday | 20 | INR 500 |
| Friday | 26 | INR 385 |
| Next Monday | 30 | INR 333 |

The ad did not get better. The sales just arrived late. If you paused on Monday night because INR 833 looked too dear, you turned off an ad that finished at INR 333.

## How to check it in Google Ads

1. Open the Campaigns page.
2. Click **Segment**.
3. Choose **Conversions**, then **Days to conversion**.

This splits your conversions by how many days after the click they happened. Google also adds a note when your date range is hit by lag, and offers conversion lag reporting for Search, Performance Max and App campaigns.

## How to handle it

- Do not judge a campaign on the last two or three days.
- Look at older weeks to see how long your buyers take. A INR 399 impulse buy may close in a day. A INR 40,000 course may take two weeks.
- Match your [attribution window](/glossary/attribution-window) to that time.
- Add the "by conv. time" columns in Google Ads if you want sales by the day they happened, not the day of the click.

See [click-through conversions](/glossary/click-through-conversion) and [how to know when to kill an ad](/guides/how-to-know-when-to-kill-an-ad).

## FAQ

### Is conversion lag the same as an attribution window?

No. Lag is how long buyers take. The window is the longest delay your tool will count.

### Does Meta have conversion lag too?

Buyers take time on every platform. Meta counts sales inside your chosen attribution window, so recent days can be incomplete there too. Check the same day again a week later.

### How long should I wait before judging an ad?

Wait about as long as your usual buyer takes to convert, then judge. Check your own lag report first.

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