The iPhone 6 Plus: At 5.5 inches, it's smaller than the iPad Mini (7.9 inches) and larger than a Pop-Tart (4.92 inches).
The iPhone 6: Smaller than a Pop-Tart at 4.7 inches and larger than an iPhone 5S at 4 inches.
Twitter via @ajs @hblodget and @preetbanerjee
For another look, here's how the iPhone 5S and Samsung Galaxy Note 3 stack up to a Pop-Tart:
Business Insider
iPhone 5, Frosted Strawberry Pop-Tart, Samsung
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iPhone 5, Frosted Strawberry Pop-Tart, Samsung Galaxy Note 3