3c Washington Grill Question

I am new to stamp collecting. Started about a year ago and grills really confuse me. I found this at a garage sale and the size is very difficult for me to tell. Any help? Is there a good way to measure. Is it better on the envelope or off?

Please do NOT remove the stamp from the envelope. A stamp "on cover" is almost invariably worth more than soaked off. This is the added value of postal history for the cancel, address, etc.

Your grill is strong enough to ID from the front. You will want to count the rows/columns of points rather than measuring dimensions. Several ways come to mind - 1) strong side lighting to create shadows. 2) a high resolution scan with the contrast exaggerated to make the points stand out more than a properly-exposed image. And lastly, it is far more likely to be one of the most common grills rather than a great rarity.

It is difficult to tell from your scan, but a good rule of thumb is 12 points across is probably a Scott 94 ("F" grill) and 14 vertical points across is probably a Scott 88 ("E" grill) neither of which is terribly valuable used. The "Z" grill can be 14 points across, but the points will be horizontal. I think the shade of your stamp is closer to a Scott 94 than anything else.

Post a scan of the full envelope (and back if there are any postal marking) and I bet you will get some really good info about the cover.