# Estimating size of large data download

**URL:** https://discourse.obspy.org/t/estimating-size-of-large-data-download/1717
**Category:** Usage Questions
**Created:** [May 24, 2023, 7:20pm UTC](https://discourse.obspy.org/t/estimating-size-of-large-data-download/1717 "2023-05-24T19:20:40Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![sdg](https://discourse.obspy.org/user_avatar/discourse.obspy.org/sdg/32/694_2.png) [@sdg](https://discourse.obspy.org/u/sdg)
#### Post date: [May 24, 2023, 7:20pm UTC](https://discourse.obspy.org/t/estimating-size-of-large-data-download/1717/1 "2023-05-24T19:20:40Z")

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Hello,

I am planning to download a large amount of waveform data using the MassDownloader. I’m wondering if anyone can offer tips for estimating the size of the download before launching it? In other words, I would like to know the number of TB of storage my download will require. I am new to ObsPy and working with waveform data, so any tips or best practices are much appreciated.

Thanks in advance,  
Simon

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### Author: ![megies](https://discourse.obspy.org/user_avatar/discourse.obspy.org/megies/32/9_2.png) [@megies](https://discourse.obspy.org/u/megies)
#### Post date: [May 25, 2023, 8:10am UTC](https://discourse.obspy.org/t/estimating-size-of-large-data-download/1717/2 "2023-05-25T08:10:46Z")

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I don’t think there is an easy way to get an estimate without some test runs. The major unknown I think is: how many stations will data be downloaded for?  
All I can think of is to first run it with only a few select timespans and then extrapolate from there to your full envisioned data set.