inaccurate calculations on shipping

[PebblesandSticks]

The past few weeks I started to realize that when doing a listing, I am getting inaccurate shipping cost calculations.  I put in 2 lbs 15 oz. to NYC and get 12.64 USPS Ground.  When I put in 1 lb. 15 oz. I get 14.95 using Ground as well.  I have noticed this happening over and over lately and I cant figure it out.  Also, if I add multiple pounds, I still get that it will cost me 12.64!  I haven't changed any settings so I don't know if its me or some sort of glitch in the calculator.  I do free shipping so I just want to know what my costs are going to be before I set a price.  Anyone else??? -Stephanie,   etsy.com/shop/PebblesandSticks

[BagmakerSupply]

USPS uses dimension weight rates based on source and destination ZIP codes. Where are you trying to get these calculations - on the listing itself?

[QuiltStencilsAndMore]

What are your package dimensions?

[funkydreamsmosaics]

Is $12.64 a regional rate box rate?  In that case, adding more weight to it won't matter.  

[BagmakerSupply]

@funkydreamsmosaics   PebblesandSticks said that she was getting prices for USPS Ground (which I presume means Parcel Select Ground) and there are no flat rates for that class of mail unless you are Amazon.

[PebblesandSticks]

I am getting my estimates from the calculator on the page where I am listing the item.  I didnt include box dimensions because I never changed those.  I was just changing the weight because I noticed that when I changed the lbs the price would go down for heavier weight which has never happened in the past.  I am not trying to do any flat rate or get a specific rate, only see what usps estimates for my size/weight package to a certain city.  On multiple listings I have done in the past few days, the price get cheaper when the package gets heavier...does that make sense?

[BagmakerSupply]

USPS rates are very bizarre - sometimes it is less expensive to ship a package in a flat rate Priority Box than than via Parcel Select Ground. And the rates for the exact same package can vary a lot depending on what the destination zip code is. I don't know if Etsy made changes to account for it, but recently there have been surcharges for "over size" packages. I'd give it a try with the package dimensions entered to see if that makes the calculator more accurate.