Flat Rate Box Selector

See whether a USPS flat-rate box beats weight-based pricing for your package.

Package weight (lb)

Fits in which flat-rate container?

Accuracy note: Flat-rate prices are exact retail; weight-based comparisons use lowest-zone retail. Based on USPS retail prices, temporary holiday prices in effect October 4, 2026 through January 17, 2027 (USPS Notice 123, checked October 7, 2026). Letter and stamp prices are not affected.

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