Flat Rate Shipping
Also known as: Flat Rate, Fixed Rate Shipping
Definition
Flat rate shipping charges a single, fixed price regardless of the package’s weight or how far it’s traveling. If it fits, it ships for one price—whether you’re sending across town or across the country.
How Flat Rate Works
Instead of calculating costs based on weight, dimensions, and destination zone, flat rate simplifies pricing:
- Choose a flat rate box or envelope size
- Pack your items (must fit and close properly)
- Pay the same price whether shipping 1 mile or 3,000 miles
USPS Flat Rate Options
USPS offers the most popular flat rate program:
| Box Type | Dimensions | Price Range* |
|---|---|---|
| Small Box | 8⅝" × 5⅜" × 1⅝" | ~$10 |
| Medium Box (Top-Load) | 11⅞" × 3⅜" × 13⅝" | ~$16 |
| Medium Box (Side-Load) | 14" × 12" × 3½" | ~$16 |
| Large Box | 12¼" × 12¼" × 6" | ~$22 |
| Padded Envelope | 12½" × 9½" | ~$10 |
| Legal Envelope | 15" × 9½" | ~$9 |
*Prices vary; check current USPS rates.
When Flat Rate Saves Money
Flat rate is ideal for:
- Heavy items - Books, tools, dense products
- Long-distance shipments - Cross-country shipping to zones 7-8
- Predictable pricing - Know exact costs before selling
When to Avoid Flat Rate
Flat rate may cost more when:
- Items are light and could ship cheaper by weight
- Destination is nearby (zones 1-3)
- Items don’t efficiently fill the flat rate box
Pro Tips
- Compare every time - Run both flat rate and standard pricing
- Free supplies - USPS flat rate boxes are free; order at usps.com
- Mix containers - Some items fit better in envelopes vs. boxes
- Regional Rate alternative - USPS Regional Rate can be cheaper for nearby zones
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