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The free boxes and envelopes on the USPS website are quite popular with shippers looking to keep packaging costs low. However, did you know that USPS lets you alter their Priority Mail Flat Rate packaging to ship weight-based Priority Mail? It’s one of the Postal Service’s best-kept secrets that not too many everyday shippers know about…but it’s a real thing, and we’re here to tell you more about it!
Table of Contents
- Where Can I Get Flat Rate Boxes or Envelopes?
- You Need to Pay for Flat Rate Postage If You Want to Use Flat Rate Boxes (Most of the Time)
- It’s Perfectly Fine to Change Flat Rate Packaging to Ship Weight-Based Priority Mail
- What If My Post Office Doesn’t Accept My Package?
Where Can I Get Flat Rate Boxes or Envelopes?
First thing’s first: if you’re in the market for some USPS flat rate boxes or envelopes, you can pick them up for free at your local Post Office. You can also order them on the Postal Service’s website, if you don’t feel like making the trek (hey, we don’t blame you).
You Need to Pay for Flat Rate Postage If You Want to Use Flat Rate Boxes (Most of the Time)
In the majority of cases, USPS is very strict about paying for the exact shipping service that’s marked on your box or envelope. For example, if you have a Priority Mail Medium Flat Rate Box, that’s the service you need to pay for. You won’t be able to ship regularly Priority Mail, Priority Mail Express, or Parcel Select Ground in that box.
The same goes for Priority Mail Express flat-rate envelopes! If you put something in a Priority Mail Express flat rate envelope and try to ship it First Class Package, guess what? USPS will charge you for Priority Mail flat rate postage.
For more information, check out our guide on paying for the service marked on your USPS-branded boxes or envelopes.
It’s Perfectly Fine to Change Flat Rate Packaging to Ship Weight-Based Priority Mail
Contrary to popular belief, you can technically alter your flat rate packaging to qualify for weight-based rates. Typically, it’s crucial that you pay for the specific service marked on your USPS box or envelope. Most postal workers will tell you that if you use flat rate packaging, USPS will charge you for the corresponding flat rate service. While this is true in 99% of cases, this one particular situation is the exception. In case you don’t believe us, check out the following direct quote from the USPS domestic mail manual:
“If [a Flat Rate Envelope] or [Flat Rate Box] is presented at the office of mailing and the customer has manipulated or reconstructed it, the container is accepted using weight and zone — not the Flat Rate price.”
In layman’s terms, that means you can ship weight-based Priority Mail instead of whatever flat rate service is marked on your box or envelope. However, the only way USPS lets you do this is if you alter the packaging in some regard! That means you can cut it down to a different size or change the shape (if you want to)…but, if you present a flat rate box or envelope without any changes, USPS will make you pay for that specific flat rate service.
What If My Post Office Doesn’t Accept My Package?
If your Post Office doesn’t accept your package, then you should present proof, or ask to speak to the Postmaster. A great place to start would be to pull up a copy of the domestic mail manual that we’ve linked above.
The key here is that flat rate envelopes must seal with the self-adhesive in order for them to truly be flat rate. Once you change it by expanding it and taping it up, USPS no longer considers them to be flat rate. So, if you change your flat rate packaging in a similar way that the picture above shows, USPS should only accept the package at weight-based rates.
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Can you modify a PMFRB and ship in via priority mail cubic? Or is cubic different than weight based priority mail?
GARY
I have some USPS Priority Mail Medium Tubes that I can use but the product I am shipping is only half the tube’s length? Can I cut these tubes in half to make (2) tubes allowing me to be charged by weight / zip code & also not to be charged the recently added fee for length over 22 inches?
Rockwell Sands
Hi Gary – I believe USPS will allow you to cut the tubes in half, as long as you still pay for Priority Mail postage for each of the two separate tubes! Doing so may in fact help you avoid the new fee for being over 22 inches in length. Worth a shot!
Jo.Larson
The cost to deliver your package international is more is why you are expected to pay more. Surely you understand that.
Elle
Can I simple cover the “flat rate” text on the boxes? Would that count as “manipulate”? I’d prefer not to hassle with restricting the box if it already fits perfectly. TIA!
Rockwell Sands
Hi Elle – Unfortunately you can’t do that…USPS has technology to determine that the boxes are Flat Rate, and covering up that text on the box won’t help. They’ll still charge you for shipping Flat Rate after the fact. Sorry I don’t have better news!
CD
If you are satisfied with the size and shape of a flat rate box, by separating the glued seam and putting it back together (adding tape to secure the seam) with the brown side out, it will automatically convert to shape-based Priority rate. A customer showed me this. It’s why USPS prints “Priority Mail Postage Required” on the inside.
Sam Smith
Elle, I frequently ship flat rate boxes by weight. I don’t purposely cover up the flat rate text but I often use so much tape that it is covered. I take such packages directly to the counter to double check shipping with a clerk if it’s critical that the package not be rejected or otherwise held up. At my local PO I haven’t had a single instance where they refused to ship by weight just because I used a FRB. Check with your local PO.
Brian
I tried to reuse a flat rate priority box by cutting it down to make two small packages about 2oz each. I printed out 2 first case labels from Ebay. but the post office sent them back stating they needed the full flat rate. When I took a printout from their website stating that a box could be modified and reused for weight and zone, they claimed that it still had to be priority not first class. Is this so.
Rockwell Sands
Hi Brian – you can alter flat rate packaging to ship regular weight-based Priority Mail, but Priority Mail only. You can’t use this type of packaging for First Class Package shipments; you need to provide your own boxes or envelopes for that service, I’m afraid.
Kim
I sent a package in small flat rate box. It was shipped in sealed poly bag with 1st class label through ebay. Once it got to customers Post Office …the post office OPEND bag then charged my customer the flat rate price?? Is this allowed??
Rockwell Sands
Hi Kim – Whoa, I’ve never heard of that before! If I were you, I would see if I could contest that rate adjustment through eBay’s shipping program, if that’s possible. Was the bag form-fit to the box, meaning that it was wrapped pretty snugly to show that there was clearly a box inside of it?
Jo Larson
You are not allowed to use USPS free supplies as packing materials, which you did in this case by putting it inside the poly mailer. The notice on the boxes say this.
Donna Clark
Does this go for international mail? I was under the shipping rate and had my own padded mailer. They didn’t have any padded flat rate mailing envelopes and I had to use a box. I ended up paying double. Plus the cheapest rate was $39.00 for 4 lbs and under, which was $10 more than the items I shipped. My padded mailing envelope should have cost $39, the smallest box cost $85 to mail.
Rockwell Sands
Hi Donna – yes, this goes for international shipments as well. If your local Post Office doesn’t have any particular packaging, you can always order what you need on the USPS website for free! They’ll deliver it right to your door. You can check out their selection here: https://store.usps.com/store/results/priority-mail/shipping-supplies-boxes/_/N-p52cprZu9qwm0
DONNA CLARK
Yes, that is what I ended up doing, ordering my envelope online. Since I don’t mail internationally often, I will just have to pay the higher price next time. International mailing, especially non-business is super expensive. I think it is politically related. It’s almost like they are discouraging you from sending a gift.