Understanding PDF Ink Coverage

What TAC actually means

TAC is the sum of the percentage values for each of the four CMYK inks on a given area of the page. A page with 100% cyan, 100% magenta, 100% yellow, and 100% black in the same spot would have a TAC of 400% technically possible but impractical. Most commercial printers set a limit between 300% and 340% for the combined CMYK value in any given area.

TAC is not a global average it's measured per pixel or per area, so a page can have very different coverage in different regions. A dark photograph might hit 380% while a white text area sits at 0%.

Why too much coverage causes problems

• Ink pooling: When too much liquid ink hits the paper at once, it doesn't absorb evenly. It pools on the surface and can smear.
• Slow drying: Heavy ink coverage takes longer to dry, which slows down finishing and can cause ink transfer onto adjacent sheets in the stack.
• Paper warping: Excessive moisture from wet ink can cause paper to curl, especially with thin stock.
• Cost surcharges: Many print vendors charge extra for high-coverage jobs because they use more ink and require longer press time.

What the limits actually are

• 300% TAC the most common limit. Safe for most coated and uncoated stocks.
• 320% TAC acceptable on higher-end coated stocks with fast-drying systems.
• 340% TAC only with specific vendor approval and appropriate stock. Rare.

When in doubt, ask your print vendor for their specific TAC limit and the color profile they want you to use. Different presses and stocks have different tolerances.

How to reduce coverage in dark areas

The most effective approach is to pull ink from heavy areas without losing the perceived darkness. Photoshop's Selective Color adjustment can target specific black regions and reduce the cyan/magenta/yellow while maintaining visual depth. Alternatively, in Acrobat's Ink Manager, you can convert rich black (C60 M40 Y40 K100 at ~240% TAC) to pure black (K100 at ~100% TAC) in shadow areas, which dramatically lowers TAC.

Check your PDF before submitting

PDFtopia's free coverage analyzer shows CMYK ink coverage for every page in your PDF, right in your browser no upload required. Spot heavy pages before they reach the press.