How many ships did Starfleet have during Star Trek Enterprise?

Question

How many ships did Starfleet have during the 22nd century? I remember and an episode where the Klingons attacked near earth and three ships came to the enterprises aid, one was the intrepid, and there was the other NX 02 that appeared later on.

Answer 1

TL;DR - We know of between 11 and 26

There's quite a few ships I've listed here, so I'm going to break it down into categories:

Certain

These are starships we know were in Starfleet's service during the 22nd century

In canon

• Columbia NX-02
• Enterprise NX-01
• Intrepid
• NX-Alpha
• NX-Beta
• NX-Delta
• Republic
• Sarajevo
• Saratoga
• Shenandoah
• Warp Delta ship

Beyond Canon

• Challenger - NX 03
• Discovery - NX 04

Uncertain

These ships may have been in Starfleet's service during the 22nd century, but we don't know for sure

Canon

• Bonaventure (C1-21) - described as an 'Early Earth Starship'; whether it was in Starfleet service at the time of Enterprise is unknown
• SS Buckaroo Banzai - this was an Earth starship, but we don't know if it was in service under Stafleet or not
• SS Emmette - again we know this was an Earth starship in the 22nd century, but don't know if it was a Starfleet vessel
• Enterprise XCV 330 - we don't know when exactly this starship was in service or if it was a Starfleet vessel, but it could well have been
• SS Hokule'a - this was serving during the 22nd century, but we don't know whether it was part of Starfleet
• HMS Lord Nelson - again, was operating in the 22nd century but we don't know whether it was in Starfleet Service
• HMS New Zealand - as above
• SS Seattle - as above
• SS Tomobiki - as above
• SS Urusei Yatsura - as above
• VK Velikan - as above
• VK Yuri Gagarin - as above

Beyond Canon

• Bonaventure (10281NCC) (TAS isn't canon)

This leaves us with 11 ships we are certain of. But there could be anywhere from 11 to 26 ships that we know of. It is quite likely Starfleet had a number more; I'm not even considering alternate timelines and the Mirror Universe. I expect that this is a gross underestimation of the number of ships Starfleet had during the 22nd century, but as I say this is just what we know of.