USPS Flat Rate Rates (2026)
2026 USPS Priority Mail Flat Rate box sizes, prices, and when Flat Rate actually saves you money.
Key Features
USPS Flat Rate Rate Table (2026)
| Weight | Zone 1-4 | Zone 5-6 | Zone 7-8 | Commercial Rate |
|---|---|---|---|---|
| Flat Rate Envelope | $10.40 | $10.40 | $10.40 | $7.90 |
| Legal Flat Rate Envelope | $10.70 | $10.70 | $10.70 | $8.15 |
| Padded Flat Rate Envelope | $11.10 | $11.10 | $11.10 | $8.50 |
| Small Flat Rate Box (8.6x5.4x1.7) | $10.85 | $10.85 | $10.85 | $8.25 |
| Medium Flat Rate Box (11x8.5x5.5) | $17.10 | $17.10 | $17.10 | $13.45 |
| Medium Flat Rate Box (14x12x3.5) | $17.10 | $17.10 | $17.10 | $13.45 |
| Large Flat Rate Box (12x12x5.5) | $22.80 | $22.80 | $22.80 | $17.75 |
| APO/FPO Large Flat Rate Box | $21.40 | $21.40 | $21.40 | $17.05 |
Best For
- Heavy items that fit in small or medium boxes
- Cross-country shipments (zones 7-8) where weight-based rates are expensive
- Consistent, predictable shipping costs
- Items over 5 lbs going long distances
- Military APO/FPO/DPO addresses
Pro Tips
- Flat Rate only saves money over regular Priority Mail for heavier items or long-distance zones - always compare both
- Order free Flat Rate boxes delivered to your door at usps.com/supplies
- The Medium Flat Rate Box comes in two shapes: cube and flat - choose based on your item
- For items under 3-4 lbs shipping to nearby zones, regular Priority Mail is usually cheaper
- Flat Rate is especially cost-effective for APO/FPO military addresses
Frequently Asked Questions
In 2026, USPS Flat Rate retail prices are approximately $10.85 for a Small Flat Rate Box, $17.10 for a Medium Flat Rate Box, and $22.80 for a Large Flat Rate Box. Commercial pricing through shipping platforms like I'd Ship That brings those down to roughly $8.25, $13.45, and $17.75 respectively.
No. Flat Rate is only cheaper for heavier packages or shipments going to distant zones (5-8). For lightweight items under 3-4 lbs shipping to nearby zones, regular weight-based Priority Mail is almost always less expensive. Always compare both options before buying a label.
USPS offers several Flat Rate box sizes: Small (8.625 x 5.375 x 1.625 in), Medium top-loading (11 x 8.5 x 5.5 in), Medium side-loading (14 x 12 x 3.5 in), and Large (12 x 12 x 5.5 in). There are also Flat Rate Envelopes, Legal Flat Rate Envelopes, and Padded Flat Rate Envelopes. All boxes are free from USPS.
No. USPS Flat Rate pricing requires the use of official USPS Flat Rate boxes or envelopes. You can order them for free at usps.com/supplies or pick them up at any Post Office. If you use your own packaging, you will be charged regular weight-based Priority Mail rates instead.
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