USPS Flat Rate Shipping Guide
Ship anything that fits at one flat price. No matter the weight or distance. All boxes are FREE from USPS.
USPS Flat Rate Prices 2025
| Box/Envelope | Dimensions | Max Weight | 2025 Retail | Online Price |
|---|---|---|---|---|
| Flat Rate Envelope | 12.5 x 9.5 in | 70 lbs | $10.10 | $8.40 |
| Legal Flat Rate Envelope | 15 x 9.5 in | 70 lbs | $10.40 | $8.70 |
| Padded Flat Rate Envelope | 12.5 x 9.5 in (padded) | 70 lbs | $10.55 | $8.85 |
| Small Flat Rate Box | 8.69 x 5.44 x 1.75 in | 70 lbs | $10.40 | $8.70 |
| Medium Flat Rate Box (top) | 11 x 8.5 x 5.5 in | 70 lbs | $17.05 | $14.35 |
| Medium Flat Rate Box (side) | 13.63 x 11.88 x 3.38 in | 70 lbs | $17.05 | $14.35 |
| Large Flat Rate Box | 12 x 12 x 5.5 in | 70 lbs | $22.45 | $19.30 |
| Large Flat Rate Board Game Box | 23.69 x 11.75 x 3 in | 70 lbs | $22.45 | $19.30 |
Online prices require buying label via USPS.com, PirateShip, or Stamps.com.
When Flat Rate Saves Money
- Heavy items — Flat rate ignores weight. Ship 70 lbs for $19.30 in large box.
- Cross-country — Flat rate ignores distance. Zone 8 costs the same as Zone 1.
- Small heavy items — Coins, tools, hardware fit in small/medium box at huge savings.
💡 Free boxes: Order unlimited free flat rate boxes at store.usps.com — delivered to your door in 5-7 days.