Drag graphics onto the map and have them scale to the right size?

I made some spell effect graphics at the 70 pixels per 5' square so they would be to scale in the game. When I drag them onto the browser to upload them they display on the map at the correct size. I then throw them into some custom folders in my art assets. If i drag them from my art asset folder when the grid is on, they resize to 1 square. If I drag them onto the map with the grid turned off they resize to to something a little smaller than 2 squares. I was sorta hoping I could just toss these graphics on the map in play without having to do any resizing. Is there a trick to this?

Hey, yes. I'm using a blank characters with name like "20 ft. radius" (Fireball). Then I will prepare the graphics as a token with right size and save it as default token for the character sheet. Then when you drop the character sheet token to the map it will be always the right size.

Thanks! Not the ideal way to do it, but I'll take a kludge over nothing :)

Also, it would be nice one day if roll20 could say.. add a hot key so when you drag art assets to your map, they scale to their original size. hint hint :)

Holding alt is supposed to do that, but it might only work on the map layer or with no grid. I actually do the same thing  Filip Č.  suggests.  I find it has the added benefit that if you set the spell character to all players, they can drag in and place spell effects for their own spells.  I additionally add details to the token like the save DC, save type, damage type, if it's concentration.  You can even add token abilities to it that provide the description, or the damage, etc.

Holding alt gives me the correct proportion, but not correct sizes.