Light, dense, small
A jewelry box or a phone case sits comfortably inside Simple Rate's Extra Small or Small tier, where a flat national price beats fussing over a zone lookup for a few dollars of weight-based pricing anyway.
UPS pricing
UPS flat rate boxes: what UPS Simple Rate actually is
UPS runs its own flat-rate product, called UPS Simple Rate, priced by five size tiers rather than by weight and zone the way its ordinary services are. Starting prices run from 12.20 USD for the smallest box up to 30.95 USD for the largest, per UPS's own page, read 2026-09-01. It is a real product, not a myth — but it is a narrow one, capped at 50 lb and one cubic foot, and it is not what SMKlog's checkout prices.
UPS's own pricing, read 2026-09-01Standard UPS Ground, captured 2026-09-01Where the two products diverge
Priced by the box, not the scale
Five cubic-inch tiers, one price per tier, no zone chart underneath.
UPS Simple Rate, tier by tier
UPS publishes the tiers as cubic-inch ranges with a starting price attached to each. Its own page states plainly that no account or contract is required to buy it, and that the price does not change with distance the way a standard UPS rate does — a New Jersey to California box in the same tier as a New Jersey to Pennsylvania box costs the same.
| Tier | Size range | Starting price |
|---|---|---|
| Extra Small | 1 to 100 cubic inches | 12.20 USD |
| Small | 101 to 250 cubic inches | 15.80 USD |
| Medium | 251 to 650 cubic inches | 18.95 USD |
| Large | 651 to 1,050 cubic inches | 24.85 USD |
| Extra Large | 1,051 to 1,728 cubic inches | 30.95 USD |
UPS names four delivery speeds under the product — next-day, second-day, three business days and five-day — but its page lists only the one starting figure per tier without saying which speed it buys. Read the starting price as a floor for the slowest option in that tier, not the fixed price you will see at checkout for every speed in it.
Past 1,728 cubic inches (one cubic foot) or 50 lb, whichever comes first, UPS states the package drops out of Simple Rate entirely and moves to standard rates, priced by dimensional weight and zone. That ceiling is tighter than it sounds: a 16 × 12 × 10 in box, an ordinary mid-size carton, already runs 1,920 cubic inches — over the cap before you have packed anything into it.
What SMKlog actually prices instead
SMKlog's checkout does not sell UPS Simple Rate. It quotes standard UPS Ground, UPS Ground Saver and the UPS air tiers, and every one of those is priced by weight and dimensional weight against a zone chart — the opposite mechanism from a flat size tier. The capture below shows what that actually does to a price as weight climbs on one fixed box.
| Weight | UPS Ground | UPS Ground Saver |
|---|---|---|
| 3 lb | $21.94 | $17.56 |
| 10 lb | $21.94 | $17.56 |
| 20 lb | $27.48 | $23.00 |
Notice the 3 lb and 10 lb rows are identical on both services. At this size, the box's dimensional weight sets the charge, so tripling the actual weight inside it changed nothing. Only at 20 lb did the scale weight finally pass the dimensional figure and pull the Ground price from $21.94 to $27.48. That is standard UPS pricing behaving exactly as UPS describes it — the largest of weight or dimensional weight, against a zone — and it is a different animal from Simple Rate's flat per-tier number.
Picking between the two
Bulky but light
A padded jacket or a lampshade can blow past Simple Rate's cubic-inch cap while weighing almost nothing, which is exactly when dimensional-weight pricing on standard UPS Ground starts to sting. Compare both before assuming flat is cheaper.
Heavy and dense
Once actual weight, not the box, is what is driving the price — tools, books, canned goods — standard weight-and-zone pricing usually wins, because Simple Rate's tiers cap out at 50 lb regardless of how light the box itself is.
The only way to know which wins on a specific box is to price both: look up the Simple Rate tier your carton falls into on ups.com, then run the same box through a weight-and-zone quote. SMKlog's calculator handles the second half.
Where these facts come from
- UPS, Flat-Rate Shipping — UPS Simple Rate's five tiers, starting prices, the 50 lb / 1,728 cubic inch ceiling, and the no-account requirement. Read 2026-09-01.
- SMKlog production checkout, quote-api.smklog.com — UPS Ground and UPS Ground Saver on one 16 × 12 × 10 in box at 3, 10 and 20 lb, Berkeley Heights NJ 07922 to Atlanta GA 30303. Captured 2026-09-01, saved to data/captures/2026-09-01/ups-flat-rate-myth.json.
UPS revises Simple Rate pricing on its own schedule and without notice. Confirm the current starting price for your tier before assuming last month's figure still holds.
UPS flat rate boxes, unpacked
Does UPS have flat rate boxes like USPS?
A different version of the same idea. UPS's product is called UPS Simple Rate: five size tiers priced by cubic inches, starting at 12.20 USD for the smallest, with a price that does not change by zone the way standard UPS rates do. UPS states no account or contract is required to use it. Read on ups.com, 2026-09-01.
What is the weight and size limit on UPS Simple Rate?
50 lb and 1,728 cubic inches, whichever is hit first. UPS states that a package measuring more than one cubic foot or weighing over 50 lb has to move on standard UPS rates instead, priced by dimensional weight and zone.
Do the Simple Rate prices change with delivery speed?
UPS's own page names four speeds under the product, next-day, second-day, three business days and five-day, and lists only a starting price per size tier without saying which speed that price buys. Treat the published figures as a floor, not the price for every option in the tier.
Can I buy UPS Simple Rate through SMKlog?
No. SMKlog's checkout quotes standard UPS Ground, UPS Ground Saver and the UPS air tiers, priced by weight and dimensional weight against a zone chart. Simple Rate sits outside that pricing engine; buy it directly from ups.com or a UPS Store counter.
Why did my box price the same at 3 lb and 10 lb on regular UPS Ground?
Dimensional weight. On a 16 x 12 x 10 in box quoted 2026-09-01, UPS Ground held at $21.94 for both 3 lb and 10 lb, because the box's dimensional weight, not the scale weight, set the charge at that size. Only once the box hit 20 lb did the scale weight overtake the dimensional figure and push the price to $27.48.