In dropboxes, package to unit ratio, i.e. P/U ratio, is the ratio of the dimensions of maximum package acceptable, of a given dropbox, to the dimensions of the given dropbox unit; it is a gauge of design quality in the home package dropbox industry.

Package size / Unit dimensions
The following is a comparison of the package/dimension (P/U) ratios for BrizeBox (BB), MailCube (MC), and other comparable units; the higher the ratio the better design, in terms of mechanism functionality and size-aesthetics:

Unit	Package (max size/inches)	Package (1)	Packages (capacity)	Dimensions (unit/inches)	P/U	Weight	Cost	Video	Link
		-----------------------							------------------------------
MC Package Carousel (concept)	15Hx15Wx35	7875 in³	25,000 in³	42" dia x 38H	50%	c.200lbs	c.$800
MC 9O1	7.5Hx15Wx11D	1238 in³	2476 in³	17Wx9.5Dx32H	23.9%	c.35lbs	N/A		(Ѻ)
BB 2XL (concept/prototype)	14Hx25Wx17D	5950 in³					$700
BB Large	9x12x17	1836 in³		20Wx13Dx34H	20.8%	59lbs	$394	(Ѻ)
BB XLarge	13x14x20	3750 in³	7500 in³	24Wx19Dx45H	18.3%	99lbs	$529
BB Small	7x8x12	788 in³		15Wx13Dx23H	17.6%	38lbs	$263
HomeScapes Smart Parcel Box XL (EU)	10Hx17Wx13D	2210 in³		17Wx21Dx40H	15.9%		$400	(Ѻ)	(Ѻ)(Ѻ)
ParcelWirx Drop Box	8Hx13Wx19D	1976 in³		17Wx21Dx36H	15.3%	58lbs	$460	(Ѻ)	(Ѻ)(Ѻ)(Ѻ) [1]
Deliver-Eze Pillar (Austria)	9Hx13Wx12D	1344 in³		17Wx17Dx35H	13.1%	53lbs	$499	(Ѻ)	(Ѻ)
DVault CS0015 (In/Out Mail top)				19Wx19Wx48H		115lbs	$899	(Ѻ)	(Ѻ)
DVault CS0023	9Hx17Wx12D	1836 in³		19Wx19Dx40H	12.7%	87lbs	$790	(Ѻ)	(Ѻ)
QualArc WF-PB003 Parcel Defender	7.5Hx16Wx11.5D	1380 in³		20Wx15Dx40H	11.5%	61lbs	$340		(Ѻ)(Ѻ)
QualArc Grandform	5Hx11Wx14D	770 in³		14Wx11x44H	11.4%		$530
CurbVault	9.5Hx18Wx5D	855 in³		12Wx13Dx50H	11.0%	131lbs	$1590	(Ѻ)	(Ѻ)
Elephant Trunk	7Hx11Wx9D	693 in³		18Wx16Dx37H	6.5%	40 lbs	$220	(Ѻ)	(Ѻ)
MailBoss Package Master	3.5Hx10.5Wx4D	147 in³		12Wx22Dx16H	5.4%	87lbs	$240	(Ѻ)	(Ѻ)(Ѻ)
Locking Security Mailbox	3.5Hx11Wx7D	270 in³		24Wx22Dx24H	4.1%	50lbs	$580	(Ѻ)	(Ѻ)
Salsbury Industries Courier Box 4975	7Hx15Wx8D	840 in³		20Wx26Dx49H	3.2%	160lbs	$750		(Ѻ)

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Dimensions | Comparisons
The following is a max package size (MPS) and cost comparison between the BBXL and the Dvault CS0015 both of which have the same MPS:

BB L Max Package Size: 9Hx17x12 Cost: $394	DVault CS0015 Max Package Size: 9Hx17x12 Cost: $899
20Wx13Dx34H (Unit Dimensions)

Max Package Size | Visuals
The following shows Max Package Sizes (MPS), for various units, to get a feel for how package to unit dimension (P/D) ratios are related to design quality:

The drop design mechanism of units such as Elephant Trunk work to limit the maximum size package the unit will accept, as compared to designs with higher P/D ratios. In other words, when HomeScapes boast that there Smart Parcel Drop Box is the “largest parcel drop box available in the UK” (Ѻ), the statement is misleading in that P/D ratios are not taken into account, i.e. the unit may be large, but it does not accept large packages.

References
1. Smith, Brad. (2018). "Email to Libb Thims", Jan 9.