Shipping · USPS
Priority Mail Flat Rate prices, box vs weight.
Every USPS Priority Mail Flat Rate envelope and box price, plus a comparison with the weight-based price for your parcel and zone.
Priority Mail Flat Rate retail prices: envelope $13.90, small box $14.65, medium box $25.80, large box $36.10. Express Flat Rate envelope: $38.25.
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USPS Priority Mail Flat Rate prices
| Packaging | Size | Retail | Commercial |
|---|---|---|---|
| Priority Mail Flat Rate Envelope | 12-1/2" x 9-1/2" or smaller | $13.90 | $11.97 |
| Priority Mail Legal Flat Rate Envelope | 15" x 9-1/2" | $14.25 | $12.51 |
| Priority Mail Padded Flat Rate Envelope | 12-1/2" x 9-1/2" | $15.00 | $12.84 |
| Priority Mail Small Flat Rate Box | 8-5/8" x 5-3/8" x 1-5/8" inside | $14.65 | $12.95 |
| Priority Mail Medium Flat Rate Box | 11" x 8-1/2" x 5-1/2" or 13-5/8" x 11-7/8" x 3-3/8" inside | $25.80 | $22.02 |
| Priority Mail Large Flat Rate Box | 12" x 11-3/4" x 5-1/2" inside | $36.10 | $32.75 |
| Priority Mail APO/FPO/DPO Large Flat Rate Box | 12" x 11-3/4" x 5-1/2" inside | $34.65 | $31.34 |
| Packaging | Size | Retail |
|---|---|---|
| Priority Mail Express Flat Rate Envelope | 12-1/2" x 9-1/2" | $38.25 |
| Priority Mail Express Legal Flat Rate Envelope | 15" x 9-1/2" | $38.55 |
| Priority Mail Express Padded Flat Rate Envelope | 12-1/2" x 9-1/2" | $39.25 |
Sizes are as printed in Notice 123 (inside dimensions for boxes). Under DMM 123.1.4 only USPS-produced Flat Rate envelopes and boxes qualify, and the price is flat regardless of domestic destination or actual weight up to 70 pounds. Flat Rate packaging is exempt from the Priority Mail nonstandard fees (DMM 123.1.6).
When is a Flat Rate box cheaper?
Compare the box price with the weight-based Priority Mail price for your weight and zone using the tool above. Heavy, dense items shipped far (higher zones) usually favour a box; light items shipped locally usually favour weight-based pricing. Also check Ground Advantage if speed is not a concern.
Frequently asked questions
How much is a Priority Mail Flat Rate box?
Retail prices are $14.65 for the small box, $25.80 for the medium box and $36.10 for the large box. The Flat Rate envelope is $13.90 (Notice 123 effective October 4, 2026).
Is Flat Rate cheaper than weight-based Priority Mail?
It depends on weight and zone. For example, a 5 lb package costs $15.10 in zone 1 but $39.00 in zone 8 by weight, while a medium Flat Rate box costs $25.80 everywhere. Use the comparison tool above.
Do Flat Rate boxes pay oversize or nonstandard fees?
No. DMM 123.1.6 exempts Flat Rate packaging from the Priority Mail nonstandard fees. Only USPS-produced Flat Rate envelopes and boxes qualify (DMM 123.1.4).
What is the difference between retail and commercial Flat Rate prices?
Notice 123 lists a lower commercial price (for example $22.02 for the medium box). Under DMM 223.1.2 commercial prices are available to Click-N-Ship customers, PC Postage users with a qualifying label, and permit imprint customers.
When do USPS prices change?
USPS usually updates its prices in January and July and can also change them at other times. This page is built from Notice 123 effective October 4, 2026. Check the effective date at the top of the official Notice 123; if a newer one is in force, use its figures.
Sources
Checked
- USPS Notice 123, Price List (HTML), effective October 4, 2026
- USPS Notice 123, Price List (PDF)
- DMM 123: Priority Mail retail prices and eligibility
- DMM 223: Priority Mail commercial prices and eligibility
- USPS Domestic Zone Chart
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Prices change: check the date
These figures are USPS list prices from Notice 123 (Price List), effective October 4, 2026, read on 18 October 2026. USPS usually updates prices in January and July and can change them at other times, so if today is after a newer Notice 123 took effect, the official notice wins. Extra services (insurance, tracking add-ons, signature, pickup) and taxes are not included.