US Tabloid is exactly 11 × 17 inches. At 150 image pixels per inch, multiplication gives 1650 pixels on the short side and 2550 on the long side, with no rounding. Portrait and landscape use the same pair in opposite order. The result is a physical-sheet calculation, not a promise about poster quality or a printer’s printable area.
Calculate the 11-inch side
Pixel width = 11 inches × 150 PPI = 1650 pixels. The multiplication is exact, so nearest-pixel rounding leaves 1650 unchanged. In portrait this is the width; in landscape it becomes the height. The underlying physical side remains exactly 11 inches.
Calculate the 17-inch side
Pixel height = 17 inches × 150 PPI = 2550 pixels. The portrait canvas is 1650 × 2550 and landscape is 2550 × 1650. Those dimensions belong to Tabloid at this selected PPI; they are not an A-series equivalent and do not create separate indexed orientation pages.
Treat 1650 × 2550 as the finished-area calculation
The result answers one bounded question: how many image pixels represent 11 × 17 inches at 150 PPI. It does not decide whether the provider prints borderless, trims an edge, enlarges, sharpens, or needs a colour profile. Check the production specification before export and add any requested allowance deliberately.