How to Calculate USPS Delivery Time
How USPS delivery time is worked out, step by step: the ZIP codes, the mail class, the USPS standard for the pair, cutoff times, Sundays and holidays.
By Hamdi Saidani.
Step-by-Step: Calculate USPS Delivery Time
Identify Your ZIP Codes
Find your origin ZIP code (where you're shipping from) and destination ZIP code (where it's going). You can find ZIP codes on USPS.com or Google Maps.
Know What the Zone Does
The zone (1 to 9) sets the price, not the delivery days. Zone 1 is the closest and Zone 8 the farthest; Zone 9 is only for Palau, Micronesia and the Marshall Islands. Our calculator shows the zone for your ZIP pair.
Choose Your Mail Class
Select the service that fits your needs: Priority Mail Express (1-3 days), Priority Mail (2-3 days), Ground Advantage (2-5 days), First-Class Mail (2-5 days for a stamped letter), or Media Mail (4-7 days).
Check Service Standards
USPS publishes a standard in days for every pair of 3-digit ZIP areas and each main mail class except Priority Mail Express; the zone only sets the price.
Priority Mail, for example, is 2 days on 18% of lower-48 routes and 3 days on the rest, and never 1 day in the directory (USPS's Priority Mail Next Day is a separate option for businesses with a USPS contract).
Account for Cutoff Times
Mail dropped after your Post Office's last collection counts as mailed the next day USPS accepts mail, and Saturday counts. Collection times vary by office, so check the posted time.
At Post Offices far from a USPS regional plant, mail goes to the plant about once a day, mostly in the morning.
Add Buffer for Variables
Holidays do not count as delivery days, and USPS asks customers to mail early in December. If the date matters, ship a day or two earlier than the standard needs.
Use Our Free Calculator
Or skip the manual steps: enter two ZIP codes and the mailing date, and the calculator shows the expected date for each mail class from USPS service standards.
Today
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All USPS holidaysReady to Calculate
Enter the two ZIP codes and the mailing date above, then press "Calculate Delivery Time" to see the expected delivery date for each mail class.
Factors That Affect USPS Delivery Time
Distance
Longer routes usually take more days, but USPS sets the days per pair of 3-digit ZIP areas, not by zone. The zone only sets the price.
Mail Class
Priority Mail Express is fastest (1-3 days). Priority Mail is fast (2-3 days). Ground Advantage (2-5 days) and Media Mail (4-7 days) are slower.
Time of Mailing
Mail dropped after your Post Office's last collection counts as mailed the next day USPS accepts mail (Saturday counts). Check the posted time at your office.
Holidays & Weekends
Sundays count as transit days, except (since April 2025) the Sunday right after a Saturday mailing (mail dropped off the day before a holiday may skip Sundays too). Holidays never count, and a result that lands on a Sunday or holiday moves to the next delivery day.
Weather Events
Severe weather (snowstorms, hurricanes) can delay mail.
Peak Seasons
USPS asks customers to mail early for the December holidays, and holidays do not count as delivery days. Ship early to be safe.
Tips for Planning Around USPS Delivery Times
Always use the full 5-digit ZIP code for both origin and destination
Check USPS service alerts for any current delays in your area
Allow a day or two extra around the December holidays
Mail before your Post Office's collection cutoff time
Use Priority Mail Express if you need a guaranteed delivery date
Track your package online to see each USPS scan
Frequently Asked Questions
How accurate are USPS delivery time estimates?
A USPS service standard is the expected number of days after USPS accepts the piece, not a guarantee: only Priority Mail Express has a money-back guarantee, and exceptions apply.
Weather, holidays and mail volume can make a piece late. USPS publishes how often it meets its standards on its Service Performance Results page (about.usps.com).
Does USPS count weekends in delivery time?
Yes.
Saturdays count, and USPS also counts Sundays as transit days, with one exception added in April 2025: mail entered on a Saturday does not count the Sunday that comes straight after it (mail entered the day before a holiday may skip Sundays too).
Holidays never count, and mail dropped off on a Sunday or holiday starts the next day USPS accepts mail.
Regular mail is not delivered on Sundays or holidays, so a result that lands on one moves to the next delivery day (Tuesday when that Monday is a holiday).
For example, a 2-day piece mailed on Friday is due Sunday and arrives Monday; the same piece mailed on Saturday is due Tuesday.
What time of day should I mail for fastest delivery?
Before your Post Office's last collection or acceptance time, which varies by office. Mail dropped after it counts as mailed the next day USPS accepts mail (a Friday drop-off after the last pickup counts from Saturday).
At Post Offices far from a USPS regional plant, mail now goes to the plant about once a day, mostly in the morning, so check the posted time.
How do I find the USPS zone between two ZIP codes?
Use our calculator or the USPS Zone Chart tool (enter your origin ZIP code to see the zone for every destination).
Zone 1 is the closest and Zone 8 the farthest; Zone 9 is only for Palau, Micronesia and the Marshall Islands. Higher zones cost more; the delivery days come from a separate USPS standard for each pair of ZIP areas.