ShipCompare estimates and compares modeled USPS, UPS and FedEx ground pricing from your package weight, size and ZIP codes, using the site's own rate-tier model, entirely in your browser.
Add box dimensions on the full tool for dimensional weight.
Enter a weight and two ZIP codes to compare.
Modeled from ShipCompare's own comparison tiers, not live carrier quotes · runs in your browser. Carriers publish binding rates at USPS, UPS and FedEx.
Open the full Rate Estimator →Compare carriers and nail your billable weight before the label prints.
Get the carrier wrong and the difference comes out of your margin, not theirs.
Enter your package details for a side-by-side modeled comparison, then confirm the exact price on the carrier's own site. Carriers bill the greater of actual weight and dimensional weight, so knowing that number before you ship prevents a billing surprise at pickup.
Want the full rate-tier breakdown behind these numbers? See the 2026 cost comparison reference.
Say you have a 4-lb box going from a warehouse in zone 3. The estimator's USPS line runs a $7 base plus $0.85 per billable pound plus $0.90 for each zone step past zone 2. At 4 lbs and zone 3, that is $7 + (4 × $0.85) + (1 × $0.90), or $11.30. UPS uses a $9 base, $0.95 per pound and $1.30 per zone step, which puts the same box at $9 + $3.80 + $1.30, or $14.10. FedEx sits close to UPS on this one: $9.50 + $3.68 + $1.25, or $14.43. USPS comes out about three dollars cheaper here, mostly because of the lower base charge, not the per-pound rate.
Push the same box out to zone 7 and the gap widens. USPS adds five more zone steps at $0.90 each, UPS adds five at $1.30, FedEx five at $1.25. The zone charge alone separates USPS and UPS by two dollars before a single extra pound gets added. That is the part of the bill people forget to check: two packages of identical weight can price differently by several dollars purely because of how far apart the ZIP codes sit.
None of this is a live quote. It is the site's own linear model, built to let you compare the three carriers on equal footing before you go check the real number on usps.com, ups.com, or fedex.com.
Guessing at weight instead of using the shipping scale's readout. A pound rounds up, not down, on every carrier here, so a 3.1-lb package bills as 4 lbs, not 3.
Skipping the box dimensions. A 16-inch cube of packing peanuts around a 2-lb item works out to roughly 29 lbs of dimensional weight at the 139 divisor, a good deal more than the item itself weighs. If you only weigh the item, the estimator (and the carrier) will still bill on the bigger number once you check the box.
Reusing an oversized box because it is free. The box costs nothing; the extra six inches of length on each side does not. Cut the DIM weight and the price usually follows.
Assuming the cheapest carrier last time is still cheapest this time. Zone, weight, and box size change the winner. The Rate Estimator above re-runs the comparison for the exact shipment in front of you instead of the one from last month.
Treating the modeled number as the final price. Fuel surcharges, residential delivery fees, and account-specific discounts are not in this model. They are in the carrier's own quote, which is why every result here links back to USPS, UPS, and FedEx directly.
The estimator returns four lines: a cheapest pick, then USPS, UPS, and FedEx separately. Read the cheapest line first, but do not stop there. If the gap between the top two carriers is under a dollar, service speed or pickup convenience may matter more than the few cents saved.
The "billable weight / zone" line under the full calculator tells you which number actually drove the price. If billable weight is higher than the actual weight you typed in, dimensional weight won, which means a smaller box would have changed the outcome. If the zone number looks high for what feels like a short trip, ZIP-to-ZIP distance does not always match intuition, especially across a state line or a mountain range.
Use the result as a shortlist, not a receipt. Take the cheapest carrier from the comparison, then get the binding number from that carrier's own rate page before you commit to a label.
Usually close, not always exact. Negotiated business rates, regional fuel surcharges, and flat-rate options can shift the real winner. Treat the modeled result as a starting shortlist.
Dimensional weight took over. Carriers bill the greater of actual and DIM weight, so a large, lightly packed box can bill heavier than the scale says.
No. The math runs in your browser and nothing you enter is sent to a server.