PostageGrid Mailing Cost Index converts the USPS First-Class Mail 1-ounce letter rate into standardized business-mailing benchmarks. The goal is to make rate changes easier to compare at practical volumes.
Methodology updated: October 8, 2026. Source rate data: U.S. Postal Service. This index measures postage value for eligible 1-ounce First-Class Mail letters; it does not represent PostageGrid retail prices.
Index methodology
For each USPS rate period, PostageGrid multiplies the current 1-ounce letter rate by four benchmark mailing volumes: 100, 500, 1,000 and 5,000 letters. The year-over-year change shows the additional postage value required at the same mailing volume.
2025–2026 Mailing Cost Index
| Benchmark volume | 2025 rate: 78¢ | 2026 rate: 82¢ | Change | Percent change |
|---|---|---|---|---|
| 100 letters | $78 | $82 | +$4 | +5.1% |
| 500 letters | $390 | $410 | +$20 | +5.1% |
| 1,000 letters | $780 | $820 | +$40 | +5.1% |
| 5,000 letters | $3,900 | $4,100 | +$200 | +5.1% |
Index interpretation
The 2026 benchmark is 5.1% higher than the 2025 benchmark because the USPS 1-ounce letter rate increased from 78¢ to 82¢. For a business mailing 1,000 eligible letters, the same volume therefore represents $40 more in postage value than under the prior rate.
Related PostageGrid datasets
- Forever Stamp Price History: 2007–2026
- Cost to Mail 100, 500 or 1,000 Letters in 2026
- 2026 Forever Stamp Rate Analysis
Primary sources
Frequently asked questions
What does the PostageGrid Mailing Cost Index measure?
It translates the USPS 1-ounce First-Class Mail letter rate into standardized 100, 500, 1,000 and 5,000-piece mailing benchmarks.
Is this an estimate of PostageGrid product prices?
No. The index measures USPS postage value for eligible mailpieces. Retail product pricing is separate.
Can this index be used for large envelopes or nonmachinable letters?
No. Those mailpieces can require different postage. The benchmark is intentionally limited to eligible 1-ounce First-Class Mail letters.