What is MTD: Maximum Tolerable Downtime

Last updated: 2025-09-02

What is MTD and why it matters for businesses 

  • MTD (Maximum Tolerable Downtime) is the longest time your business can accept a process, service, or system being down before it causes serious impact. 
  • It’s the point where an outage becomes unacceptable—leading to financial loss, compliance/legal issues, reputational damage, or safety risks.  

Examples of maximum tolerable downtime for common business processes

  • Electric power - MTD 2 minutes (almost everything stops without electricity)
  • Customer support – MTD 4 hours (issues pile up fast and customer trust drops)
  • Cleaning services - MTD 3 days (short outages are usually manageable)
  • Document archive – MTD 7 days (short outages are usually acceptable)

Example MTD tiers

  • 0–4 hours (immediately critical)
  • up to 24 hours
  • up to 72 hours
  • up to 7 days

In short: MTD = the maximum acceptable downtime for a process before major damage occurs.

What is recovery time? 

  • Recovery time is measured from the start of the outage until the process is running again (or a workable workaround is in place).
  • Recovery time must fit within the outage window (MTD is always longer than RTO).
  • Set RTO (Recovery Time Objective) below MTD — so you restore the system before the downtime becomes critical.