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How much is a Priority Mail Flat Rate box in 2026?

A Small Flat Rate Box costs $14.65 at the Post Office and $12.95 online; a Medium box $25.80 or $22.02; a Large box $36.10 or $32.75. The Flat Rate Envelope is $13.90 ($11.97 online). Each price covers up to 70 lb to any domestic address, and online labels (USPS's commercial prices) save $1.70 to $3.78 per piece.

Temporary holiday prices. These include USPS's holiday add-on, in effect from 12 a.m. CT Oct 4, 2026 to 12 a.m. CT Jan 17, 2027, on top of the 8% time-limited increase in place since Apr 26, 2026. What each product cost before

From the current USPS Notice 123, which matches USPS's price file. Price history since 2009: CSV or JSON (CC BY 4.0).

Rates verified on

Every Flat Rate envelope and box: Post Office vs online

Retail is what the Post Office counter charges (and what Forever Prepaid Flat Rate packaging costs, DMM 123.1.4.3). Online is USPS's commercial price, for Click-N-Ship and PC Postage labels (DMM 223.1.2).

USD per piece, any weight up to 70 lb, any domestic address. USPS Notice 123 effective Oct 4, 2026 (holiday prices to 12 a.m. CT Jan 17, 2027); "Before Oct 4" is the Jul 12, 2026 list. Sizes in inches, from Notice 123.
ProductSize (inside)Post OfficeOnlineOnline savesBefore Oct 4 (PO / online)
Flat Rate Envelope 12-1/2 x 9-1/2 in. or smaller $13.90 $11.97 $1.93 (14%) $12.90 / $11.12
Legal Flat Rate Envelope (packaging at USPS.com only) 15 x 9-1/2 in. $14.25 $12.51 $1.74 (12%) $13.25 / $11.66
Padded Flat Rate Envelope (packaging at USPS.com only) 12-1/2 x 9-1/2 in. $15.00 $12.84 $2.16 (14%) $14.00 / $11.99
Small Flat Rate Box 8-5/8 x 5-3/8 x 1-5/8 in. $14.65 $12.95 $1.70 (12%) $13.65 / $12.10
Medium Flat Rate Box 11 x 8-1/2 x 5-1/2 in., top-loading (FRB-1)
13-5/8 x 11-7/8 x 3-3/8 in., side-loading (FRB-2)
$25.80 $22.02 $3.78 (15%) $24.80 / $21.17
Large Flat Rate Box 12 x 11-3/4 x 5-1/2 in. $36.10 $32.75 $3.35 (9%) $34.00 / $31.00
APO/FPO/DPO Large Flat Rate Box (APO/FPO/DPO addresses only) 12 x 11-3/4 x 5-1/2 in. $34.65 $31.34 $3.31 (10%) $32.55 / $29.59
  • The cheapest Flat Rate option is the Flat Rate Envelope at $11.97 online. Any USPS-produced Priority Mail envelope smaller than the 9-1/2 x 12-1/2 in. EP14F envelope pays that price whether or not it says "Flat Rate" (DMM 123.1.4.1). USPS lists the Window Flat Rate Envelope (10 x 5 in. or 12-1/2 x 9-1/2 in.) and the Small Flat Rate Envelope (10 x 6 in.) at the same price (USPS).
  • Long and flat? USPS's Priority Mail page lists a Large Flat Rate Board Game Box (inside 23-11/16 x 11-3/4 x 3 in., outside 24-1/16 x 11-7/8 x 3-1/8 in.) at the Large box price, $36.10 or $32.75 online (USPS, checked Oct 19, 2026), though neither Notice 123 nor the DMM's list of Flat Rate Boxes (123.1.4.2) names it, so confirm it at the counter or in the USPS store before you count on it. Flat Rate packaging pays no length or nonstandard fees (DMM 123.1.6).
  • APO/FPO/DPO box: $1.45 less than the Large box at the counter ($1.41 online), same size, but only to a military or diplomatic address; anywhere else it pays the Large price (DMM 123.1.4.2). It isn't sold as Forever Prepaid packaging (DMM 123.1.4.3).
  • Included: USPS Tracking and "up to $100 of insurance with most shipments (restrictions apply)", though USPS footnotes the tracking with "Excludes Prepaid Forever Priority Mail Flat Rate products" (more); the label needs a USPS Tracking barcode for that insurance, and insurance you buy on top replaces it rather than adding to it (USPS, included insurance). USPS's delivery objective is 2 to 3 days, not guaranteed (DMM 123.2.1).
  • No reusing Priority boxes for cheaper mail. USPS-produced packaging pays its own product's price however it's reconfigured or marked over (DMM 601.6.1). More on that.

Is Flat Rate cheaper than Ground Advantage? From what weight, zone by zone

Flat Rate pays one price; Ground Advantage and Priority Mail by weight rise with weight and distance. Each cell is the weight above which the Flat Rate product costs less than a by-weight label to that zone, comparing online with online. A Medium box beats an online Ground Advantage label only for packages over 22 lb to Zone 1, over 20 lb to Zone 4 and over 6 lb to Zone 8. From 1 to 70 lb, Priority Mail by weight never costs less than Ground Advantage at the same weight and zone, online or at the counter, so "cheaper than Ground Advantage" is the harder test.

Online (commercial) prices, Notice 123 effective Oct 4, 2026: Flat Rate vs USPS Ground Advantage by weight. "over 22 lb" means a package heavier than 22 lb. Zone distances: DMM 608.9.
Flat Rate (online)Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6Zone 7Zone 8Zone 9
Flat Rate Envelope $11.97over 9 lbover 9 lbover 7 lbover 5 lbover 2 lbover 1 lbover 1 lbover 1 lbover 1 lb
Small Box $12.95over 10 lbover 10 lbover 8 lbover 7 lbover 3 lbover 2 lbover 2 lbover 1 lbover 1 lb
Medium Box $22.02over 22 lbover 21 lbover 21 lbover 20 lbover 13 lbover 10 lbover 8 lbover 6 lbover 6 lb
Large Box $32.75over 30 lbover 26 lbover 25 lbover 24 lbover 22 lbover 20 lbover 17 lbover 13 lbover 13 lb
Post Office (retail) prices: Flat Rate vs Ground Advantage retail by weight.
Flat Rate (Post Office)Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6Zone 7Zone 8Zone 9
Flat Rate Envelope $13.90over 5 lbover 4 lbover 3 lbover 2 lbover 1 lbover 1 lbover 1 lbover 1 lbover 1 lb
Small Box $14.65over 6 lbover 5 lbover 4 lbover 3 lbover 1 lbover 1 lbover 1 lbover 1 lbover 1 lb
Medium Box $25.80over 20 lbover 20 lbover 20 lbover 16 lbover 10 lbover 8 lbover 6 lbover 4 lbover 4 lb
Large Box $36.10over 25 lbover 24 lbover 22 lbover 20 lbover 18 lbover 13 lbover 10 lbover 8 lbover 8 lb
Online prices: Flat Rate vs Priority Mail by weight (commercial). This is the test if you want Priority Mail's speed.
Flat Rate (online)Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6Zone 7Zone 8Zone 9
Flat Rate Envelope $11.97over 4 lbover 4 lbover 3 lbover 2 lbany weightany weightany weightany weightany weight
Small Box $12.95over 7 lbover 6 lbover 3 lbover 2 lbany weightany weightany weightany weightany weight
Medium Box $22.02over 20 lbover 20 lbover 15 lbover 11 lbover 4 lbover 3 lbover 3 lbover 3 lbany weight
Large Box $32.75over 25 lbover 24 lbover 23 lbover 21 lbover 10 lbover 7 lbover 5 lbover 5 lbany weight
  • Envelopes: a Flat Rate Envelope ($11.97 online) beats Ground Advantage only for contents over 9 lb to Zone 1 and over 1 lb to Zone 8, so it pays off for dense paper, not light items.
  • Size, not just weight: a by-weight box over 1 cubic foot (1,728 cubic inches) is billed at the greater of its actual and dimensional weight (DMM 123.1.3), so a big light box can cost more than these tables show. No Flat Rate box is that big; the tables compare by actual weight.
  • Books and media? Media Mail is priced by the pound for any distance: $12.50 for 12 lb, against $22.02 for a Medium box online. It's slower and only for qualifying media (Media Mail rates).

Full by-weight tables: Priority Mail prices by weight and zone · Ground Advantage rates · small dense items: Ground Advantage Cubic

Worked examples (online prices)

  • A 3 lb pack of small parts that fits a Small box, Zone 8: Small Flat Rate Box $12.95, Ground Advantage $16.30, Priority Mail by weight $21.42. Cheapest: Small Flat Rate Box, $3.35 under Ground Advantage.
  • A 4 lb pair of boots that needs a Medium box, Zone 4: Medium Flat Rate Box $22.02, Ground Advantage $11.30, Priority Mail by weight $15.61. Cheapest: Ground Advantage, $10.72 under the Flat Rate box; Priority by weight is $6.41 under the box too.
  • A 12 lb box of hand tools, Zone 8: Medium Flat Rate Box $22.02, Ground Advantage $30.48, Priority Mail by weight $50.10. Cheapest: Medium Flat Rate Box, $8.46 under Ground Advantage.
  • A 25 lb box of cast-iron parts, Zone 5: Large Flat Rate Box $32.75, Ground Advantage $48.69, Priority Mail by weight $63.36. Cheapest: Large Flat Rate Box, $15.94 under Ground Advantage.
  • A 5 lb gift box to Palau, Micronesia or the Marshall Islands, Zone 9: Medium Flat Rate Box $22.02, Ground Advantage $20.24, Priority Mail by weight $64.02. Cheapest: Ground Advantage, $1.78 under the Flat Rate box; if it has to go Priority, the box saves $42.00 over Priority by weight.

Zone 9 is Palau, Micronesia and the Marshall Islands, mailed as domestic mail (DMM 608.2.2); Flat Rate costs the same there as anywhere else.

Holiday prices until Jan 17, 2027

From 12 a.m. CT Oct 4, 2026 to 12 a.m. CT Jan 17, 2027, USPS adds $1.00 to every Flat Rate product at retail except Large Flat Rate Boxes, which get $2.10; online it's $0.85 and $1.75 (USPS, Aug 25, 2026). The APO/FPO/DPO box gets the Large box add-on, as its Jul 12 price shows. The "Before Oct 4" column above is the Jul 12, 2026 list, and each price there plus the add-on equals today's price. Those Jul 12 prices already carried USPS's 8% time-limited increase from Apr 26, 2026 (tracker entry); before it, a Medium box was $22.95 at the counter.

Both temporary changes end on Jan 17, 2027. As of Oct 19, 2026, USPS hadn't published the Flat Rate prices that apply from Jan 17, 2027, so we don't show a forecast. What's known about 2027 prices · holiday prices in the tracker

Holiday add-on on the regular Flat Rate Envelope at retail, by season: 2021 $0.75, 2022 $0.95, 2024 $0.60, 2025 $0.90 and 2026 $1.00. USPS added none in 2023 (its Sep 19, 2023 announcement: no holiday surcharges).

Flat Rate prices since 2009 (Post Office)

  • Medium box: $10.35 on Jan 18, 2009, $25.80 now with the temporary prices (+149%). Small box: $4.95 to $14.65 (+196%); Large: $13.95 to $36.10 (+159%).
  • The Small box is new since 2009: USPS introduced it on Jan 18, 2009 at the Flat Rate Envelope's price, $4.95 (Postal Bulletin 22247). Legal and Padded envelopes first appear with a retail price in the Notice 123 effective Jan 2, 2011; in 2010 the padded envelope was a Commercial Plus price only (Postal Bulletin 22273).
  • Price cuts are rare: outside the end of a holiday season, a retail Flat Rate price went down only 3 times: Flat Rate Envelope $4.95 to $4.90 on Jan 4, 2010, Large Box $21.90 to $21.50 on Jan 9, 2022 and APO/FPO/DPO Large Box $20.40 to $20.00 on Jan 9, 2022.
  • The military discount shrank: the APO/FPO/DPO box was $2.00 under the Large box until Jan 21, 2017; it's $1.45 under now.
USPS retail Flat Rate prices, one row per price period, newest first; temporary prices marked. Each row is from the USPS price list or Postal Bulletin linked in the last column and checked against another USPS document (the CSV and JSON list every one). A dash means USPS listed no retail price.
In effectFlat Rate Env.Legal Env.Padded Env.Small BoxMedium BoxLarge BoxAPO/FPO LargeSource
Oct 4, 2026 to nowholiday prices $13.90$14.25$15.00$14.65$25.80$36.10$34.65 Notice 123
Apr 26, 2026 to Oct 3, 20268% time-limited increase $12.90$13.25$14.00$13.65$24.80$34.00$32.55 Notice 123
Jan 18, 2026 to Apr 25, 2026 $11.95$12.25$12.95$12.65$22.95$31.50$30.15 Notice 123
Oct 5, 2025 to Jan 17, 2026holiday prices $11.90$12.10$12.85$12.60$21.95$31.40$30.15 Notice 123
Jul 13, 2025 to Oct 4, 2025 $11.00$11.20$11.95$11.70$21.05$29.95$28.70 Notice 123
Jan 19, 2025 to Jul 12, 2025 $10.10$10.40$10.85$10.65$19.15$26.30$25.05 Notice 123
Oct 6, 2024 to Jan 18, 2025holiday prices $10.45$10.75$11.20$11.00$19.30$26.00$24.25 Notice 123
Jan 21, 2024 to Oct 5, 2024 $9.85$10.15$10.60$10.40$18.40$24.75$23.00 Notice 123
Jan 22, 2023 to Jan 20, 2024 $9.65$9.95$10.40$10.20$17.10$22.80$21.20 Notice 123
Oct 2, 2022 to Jan 21, 2023holiday prices $9.90$10.20$10.60$10.40$17.05$22.45$20.95 Notice 123
Jan 9, 2022 to Oct 1, 2022 $8.95$9.25$9.65$9.45$16.10$21.50$20.00 Notice 123
Dec 26, 2021 to Jan 8, 2022 $7.95$8.25$8.55$8.45$15.50$21.90$20.40 Notice 123
Oct 3, 2021 to Dec 25, 2021holiday prices $8.70$9.00$9.30$9.20$16.25$22.65$21.15 Notice 123
Jan 24, 2021 to Oct 2, 2021 $7.95$8.25$8.55$8.45$15.50$21.90$20.40 Notice 123
Jan 26, 2020 to Jan 23, 2021 $7.75$8.05$8.40$8.30$15.05$21.10$19.60 Notice 123
Jan 27, 2019 to Jan 25, 2020 $7.35$7.65$8.00$7.90$14.35$19.95$18.45 Notice 123
Jan 21, 2018 to Jan 26, 2019 $6.70$7.00$7.25$7.20$13.65$18.90$17.40 Notice 123
Jan 22, 2017 to Jan 20, 2018 $6.65$6.95$7.20$7.15$13.60$18.85$17.35 Notice 123
Jan 17, 2016 to Jan 21, 2017 $6.45$6.45$6.80$6.80$13.45$18.75$16.75 Notice 123
Sep 7, 2014 to Jan 16, 2016 $5.75$5.90$6.10$5.95$12.65$17.90$15.90 Notice 123
Jan 26, 2014 to Sep 6, 2014 $5.60$5.75$5.95$5.80$12.35$17.45$15.45 Notice 123
Jan 27, 2013 to Jan 25, 2014 $5.60$5.75$5.95$5.80$12.35$16.85$14.85 Notice 123
Jan 22, 2012 to Jan 26, 2013 $5.15$5.30$5.30$5.35$11.35$15.45$13.45 Postal Bulletin
Jan 2, 2011 to Jan 21, 2012 $4.95$4.95$4.95$5.20$10.95$14.95$12.95 Notice 123
Jan 4, 2010 to Jan 1, 2011 $4.90--$4.95$10.70$14.50$12.50 Notice 123
Jan 18, 2009 to Jan 3, 2010 $4.95--$4.95$10.35$13.95$11.95 Postal Bulletin

Questions

How much is a Flat Rate box at the Post Office in 2026?

Small $14.65, Medium $25.80 and Large $36.10; the APO/FPO/DPO Large box is $34.65. Envelopes are $13.90 (regular), $14.25 (Legal) and $15.00 (Padded) (USPS Notice 123). These include USPS's holiday add-on until 12 a.m. CT Jan 17, 2027.

How much cheaper is Flat Rate online?

$1.70 to $3.78 per piece: USPS's commercial prices, which DMM 223.1.2 makes available to Click-N-Ship and PC Postage customers, are $12.95 for a Small box, $22.02 for a Medium and $32.75 for a Large. Label services and selling platforms can charge their own rates.

Is Flat Rate cheaper than Ground Advantage?

Only when the package is heavy for its box, and sooner the farther it goes. Online, a Small Flat Rate Box ($12.95) beats a Ground Advantage label for packages over 1 lb to Zone 8 but only over 10 lb to Zone 1; a Medium box ($22.02) over 6 lb (Zone 8) and over 22 lb (Zone 1); a Large box ($32.75) over 13 lb and over 30 lb. Lighter than that, Ground Advantage costs less. It is slower: USPS says 2-5 days, against 2-3 days for Priority Mail (USPS).

What is the weight limit for a Flat Rate box?

70 lb. USPS charges one price "regardless of the domestic destination or actual weight (up to 70 pounds)" (DMM 123.1.4). The limit in practice is the box: the item has to fit with the flaps closed "within the normal folds" (USPS).

Can I use my own box and still pay the Flat Rate price?

No. "Only USPS-produced Flat Rate Envelopes or Flat Rate Boxes are eligible for the Flat Rate price" (DMM 123.1.4); in your own box you pay Priority Mail by weight and zone (USPS). The one stretch: any USPS-produced Priority Mail envelope smaller than the EP14F envelope pays the Flat Rate Envelope price even if it isn't marked Flat Rate (DMM 123.1.4.1). USPS lists Flat Rate boxes and envelopes as free supplies, delivered "with your regular mail usually within 7 to 10 days" (USPS).

What is Forever Prepaid Flat Rate packaging, and does it cost more?

It's a Flat Rate envelope or box with the postage already on its label, sold "only online at www.usps.com" for the Regular, Padded and Legal envelopes and the Small, Medium and Large boxes. It costs the same as the Post Office price, so $25.80 for a Medium box today; the label can't be moved to other packaging, and it can go to APO/FPO/DPO addresses but without the military discount (DMM 123.1.4.3). One thing to ask about before you buy: on USPS's Priority Mail page, the line "Includes USPS Tracking" carries the footnote "Excludes Prepaid Forever Priority Mail Flat Rate products," and the page doesn't explain it (USPS, checked Oct 19, 2026).

Can I turn a Flat Rate box inside out and ship it Ground Advantage?

No. Mail sent in USPS-produced packaging pays that product's price "regardless of how the packaging is reconfigured or how markings may be obliterated" (DMM 601.6.1). A Priority Mail or Flat Rate box ships Priority Mail. The same rule bars hazardous materials and live animals from USPS-produced packaging, except Ground Advantage and Connect Local packaging. More: can you use a Priority Mail box for Ground Advantage?

Do Flat Rate boxes pay oversize or nonstandard fees?

No. Priority Mail's length, 2 cubic foot and nonstandard-characteristics fees apply "Except for Flat Rate packaging" (DMM 123.1.6), and USPS says Flat Rate packaging "is exempt from all Nonstandard Fees" (USPS). No Flat Rate box is over 1 cubic foot, the size where Priority Mail's dimensional weight starts (DMM 123.1.3).

How much cheaper is the APO/FPO Flat Rate box?

$1.45 at the Post Office ($34.65 vs $36.10) and $1.41 online ($31.34 vs $32.75). It's the same size as the Large box and only gets that price to an APO, FPO or DPO address; sent anywhere else it pays the Large box price (DMM 123.1.4.2). Forever Prepaid packaging can go to those addresses too, but without the military discount (DMM 123.1.4.3). In 2009 the discount was $2.00 (Postal Bulletin 22247). Addressing and customs rules: shipping to APO, FPO and DPO addresses.

Does any Priority Mail envelope get the Flat Rate price?

Any USPS-produced Priority Mail envelope smaller than the 9-1/2 x 12-1/2 in. EP14F envelope does, "whether or not they are marked 'Flat Rate Envelope'" (DMM 123.1.4.1). USPS lists the Window and Small Flat Rate Envelopes at the regular $13.90 price (USPS). The Legal ($14.25) and Padded ($15.00) envelopes have their own prices, and Notice 123 notes their packaging is only available at USPS.com.

Is Flat Rate the same price to Hawaii, Alaska and Zone 9?

Yes, one price to any domestic address. Mail to Palau, Micronesia and the Marshall Islands (Zone 9) "is treated as if it were domestic mail" (DMM 608.2.2), where Priority Mail by weight costs far more: $64.02 online for 5 lb against $22.02 for a Medium box. A Priority Mail piece of 16 oz or more to these islands, or to the other ZIP Codes in the DMM's table (Guam, American Samoa and the Northern Mariana Islands among them), needs a computer-generated customs form unless it also goes Registered Mail (DMM 608.2.3.1).

Will Flat Rate prices go down after Jan 17, 2027?

The holiday add-on ($1.00 on most products, $2.10 on Large boxes at retail) ends at 12 a.m. CT on Jan 17, 2027 (USPS, Aug 25, 2026), and so does the 8% time-limited increase from Apr 26, 2026. USPS said that at that time it "can determine if a different long-term approach is needed" (USPS, Mar 25, 2026). As of Oct 19, 2026, USPS hadn't published the Flat Rate prices that apply from Jan 17, 2027, so we don't show a forecast.

How we built this

Today's prices come from the current Notice 123, read on Oct 19, 2026; every Priority Mail, Flat Rate and cubic price on it matched USPS's price change file, and each equals the Jul 12, 2026 price plus the add-on USPS announced. The comparisons are computed from those tables and Ground Advantage's, at USPS's published prices; label services can charge less. For the history we read the retail Priority Mail section of every archived Notice 123 since 2009 on USPS's Postal Explorer archive, keyed each copy to the effective date printed on it, took 2009 from Postal Bulletin 22247 (which gives the date the prices started) and 2012 from Postal Bulletin 22326 and USPS's price filing (the only archived 2012 list is a draft), and checked every row against another USPS document, including USPS price files from 2017.

Related: Priority Mail prices by weight, Ground Advantage Cubic rates, USPS shipping cost by weight, USPS holiday prices, all price histories.

Sources

Rates verified on from each official page below.

Free 1-page Reseller Cheat Sheet: fees on 8 platforms, Media Mail and stamp prices

What each platform takes from a $10, $25 and $50 sale, Media Mail 1-10 lb, Ground Advantage to Zones 1, 5 and 8, and the Forever stamp, on one printable page. The link appears as soon as you sign up.