[Updated version with a fixed-sized Rarity]
 
Original chart by “Joetheimpaler”  
http://joetheimpaler.deviantart.com/  
>>1150198
 
Many extra MLP monsters added by user “Markiz93” on derpibooru  
>>1154012
 
This version compiled by “Cirrus Light” on derpibooru, or “Eagle1division”  
http://eagle1division.deviantart.com/
 
The Space Shuttle, Jet, and missiles by  
bagera3005.deviantart.com
 
Naval Destroyer by  
ColosseumSB.deviantart.com
 
Rarity on the Abrams by  
delphince.deviantart.com
 
And the pilot Rainbow Dash by the F/A-18 by  
karpiupl.deviantart.com
 
Protected under fair use for educational purposes.
 
This is based off of a size comparison that can be found at:  
https://www.derpibooru.org/991140
 
On that page, there is a source link to the youtube video. Four different methods of pony height mesurement converge to around 98 cm. This was used as a rough guide for this comparison. 1 pony = ~ 40 pixels ~ 1 meter.
 
Recent “Equestria Girls outtakes” video shows “human” Rainbow Dash riding pony Rainbow Dash, and roughly agrees with this metric.
 
For an extended size comparison of real objects, visit:
 
http://www.projectrho.com/public_html/rocket/supplement/sizechart.html
 

 
…Maybe I should make a higher-res version? I scaled it down to 25% of the original size because the file size was getting ridiculous with the further expansion, and it was getting laggy to work on it. I could re-make it at 50% scale, though.
 
Read the thingies in it.
 
This is why I think nukes are massively under-appreciated in fiction :P
 
Also, apparently a tank would probably win against an Ursa Minor.
 
I’m really surprised by how small everything is. Especially the hydra.
 
I mean, freakishly terrifying to fight in person. But not so big compared to ships, shuttles, jets, or even tanks…