Offset (Litho) Printing

What is offset printing?

Offset lithography, usually called offset printing, is the most widely used method for printing paperboard packaging. Ink is transferred from a metal printing plate to a rubber blanket and then onto the board, which is why it is called "offset": the plate never touches the board directly. Each color has its own plate.

Lithography relies on the principle that oil and water do not mix. The image areas of the plate attract ink, and the non-image areas attract water and repel ink. The result is extremely sharp detail, smooth gradients and consistent color across long runs.

Strengths of offset printing

• Sharp detail for small text, fine lines and photography
• Accurate, consistent color, including true Pantone spot colors
• Lowest unit cost at volume once plates are made
• Wide range of inks: metallics, fluorescents, opaque whites
• In-line coatings such as aqueous and UV

Limitations

• Setup cost: plates and press make-ready add a fixed cost per color and design
• Less economical for very short runs or many versions
• Lead time for platemaking

Offset vs. digital vs. flexo

CMYK and Pantone

Offset can print in CMYK process (four colors combined in dots) and spot colors mixed to exact Pantone references. Many packaging jobs combine both: CMYK for images and one or two Pantone colors for brand-critical elements.

How offset lithography works

Offset lithography is based on a simple principle: oil and water do not mix.

1. Plates. Each color in your design gets its own aluminum plate. The image areas are treated to attract oily ink; the non-image areas attract water.
2. Inking and dampening. On the press, rollers apply a thin film of water and then ink to each plate. Ink sticks only to the image areas.
3. Offset to blanket. The inked image transfers ("offsets") from the plate to a rubber blanket cylinder.
4. Blanket to sheet. The blanket presses the image onto the paperboard sheet.
5. Next color. The sheet passes through one printing unit per color, typically four for CMYK plus extra units for Pantone spot colors and an in-line coating unit.

The rubber blanket conforms to the board surface, giving sharp, consistent images even on slightly textured stocks. Modern sheet-fed offset presses for cartons print thousands of sheets per hour with precise color control.

Why offset is the premium carton standard

• Image quality: fine screens, smooth gradients, crisp small type.
• Color fidelity: process colors plus true Pantone spot inks, metallic and fluorescent inks.
• Consistency: closed-loop color measurement keeps long runs and reorders consistent.
• Efficiency at volume: after setup, the cost per sheet is low.
• Finishing compatibility: in-line aqueous or UV coating, then lamination, foil, emboss and die-cutting.

Offset economics

Offset has meaningful setup costs: plates for every color, press make-ready (getting ink, water and registration right) and waste sheets while the press comes up to color. These are spread across the run. That makes offset the most economical choice for cartons at roughly 1,000 units and above, and especially at 5,000 to 50,000+.

Each carton sheet usually carries several cartons ("ups"). The more cartons fit on one sheet, the lower the cost per carton. Your carton size and the sheet size of the press both influence price, which is one reason small changes in dimensions can sometimes change a quote noticeably.

The price table on this page shows estimated unit prices for cartons at 1,000 to 10,000 units.

Spot colors and special inks

Offset's ability to print spot inks is a major advantage for brands with strict color standards.

A typical premium carton might print CMYK + one Pantone brand color + aqueous coating, then receive a soft-touch lamination and gold foil logo.

Color management on offset

Offset printers measure color with spectrophotometers and control it to industry standards (for example ISO 12647 or G7 gray balance). For you, that means:

• Proofs can predict the result: contract proofs simulate the printed color.
• Reorders match when printed to the same standard and board.
• Approved samples become your reference for future runs.

Supply Pantone references for key colors and tell us about any color that is critical.

Boards printed by offset

Litho-lamination: offset quality on corrugated

Corrugated board is too thick and uneven to pass through a sheet-fed offset press. Litho-lamination solves this: a paper top sheet is printed by offset, then glued (laminated) onto single-face or single-wall corrugated. The result combines offset image quality with corrugated strength, used for premium mailers, retail-ready shipping boxes and displays. It involves an extra step and typically higher minimums than digital printing on corrugated.

File preparation for offset

• CMYK + named Pantone spot colors (no RGB elements)
• Overprint settings checked (especially for black text and finish layers)
• Rich black for large areas; 100% K for small text
• Total ink coverage under about 300%
• Trapping handled by prepress, but avoid tiny gaps between colors
• 300 ppi images at final size
• 1/8 in bleed and safe zones on the dieline

See our artwork guidelines.

• CMYK images at 300 ppi; Pantone spot colors named correctly
• Rich black for large dark areas; 100% K for small text
• 1/8 in bleed and safe margins
• Separate layers for finishes (foil, spot UV, emboss)

See our artwork guidelines and printing guide.

Box StylesFolding CartonsLightweight printed paperboard cartons that ship flat and fold up fast on your packing line. Box StylesTuck End BoxesStraight and reverse tuck end cartons that open and reclose cleanly. Ideal for lightweight retail products. Box StylesRigid BoxesLuxury setup boxes made from thick greyboard wrapped in printed or specialty paper. IndustriesCosmetic BoxesMakeup and beauty cartons with premium finishes and compliant label space.

When to choose offset

• Quantities of about 1,000+ per design for cartons
• Exact Pantone colors are critical
• Special inks (metallics, fluorescents) are part of the design
• Premium retail cartons with fine detail
• Long-term reorders where consistency matters

Choose digital printing for short runs and many versions; choose flexographic printing for simple graphics on shipping boxes at volume.

Inside an offset carton job: from file to finished cartons

1. Prepress. Your artwork is checked, colors are separated into plates, traps are added, and multiple cartons are arranged ("imposed") on a press sheet. A digital contract proof can be produced to simulate the printed color.
2. Plate making. Computer-to-plate (CTP) systems image each aluminum plate directly from the file with lasers.
3. Make-ready. Plates are mounted, inks loaded, and the press is adjusted for registration and color. Operators print make-ready sheets until color matches the approved standard.
4. Production run. Sheets are printed at high speed while inline cameras and spectrophotometers monitor color and registration.
5. Coating. An in-line aqueous or UV coating unit protects the print as it leaves the press.
6. Finishing. Off-line steps add lamination, foil stamping, embossing and spot UV.
7. Die-cutting and stripping. A die-cutter cuts and creases the cartons; waste is removed.
8. Window patching and gluing. Windows are applied, and cartons are folded and glued on a folder-gluer.
9. Inspection and packing. Cartons are checked, counted and packed flat.

Imposition: why carton size affects price

Offset presses print large sheets, and several cartons are printed on each sheet. The number of cartons per sheet (the "number up") strongly affects cost. A carton that fits 12 up on a sheet costs less to print than one that fits only 8 up, even if the cartons are similar in size. When we quote, we consider the best layout for your size. If your size is flexible, we can sometimes suggest a small dimension change that improves sheet usage and lowers the price.

Ganging and shared runs

When several cartons share the same board and finishes, they can sometimes be printed together on one sheet ("ganging"). This spreads plate and make-ready costs across several designs. It is useful for product lines with several SKUs in similar sizes. Ask about ganging if you have multiple cartons to order at the same time.

Proofing offset jobs

For most jobs, a PDF proof and 3D preview are sufficient. For brand-critical colors, ask for a contract proof or a printed sample.

Offset and sustainability

Modern offset printing has improved substantially in environmental terms:

• Vegetable- and soy-based inks are available for many applications.
• Process-free and chemistry-free plates reduce plate-processing chemicals in some print shops.
• Make-ready waste is reduced by automation and color control.
• Aqueous coatings keep cartons easy to recycle.
• Efficient imposition minimizes board waste.

The largest gains, however, still come from right-sizing cartons and choosing appropriate board and finishes.

Worked example: a supplement line

A supplement brand sells six products in 2.5 × 2.5 × 5 in cartons, 3,000 of each per order.

1. Process: offset, ganged on shared sheets because the cartons share size and board.
2. Board: 18pt SBS.
3. Inks: CMYK plus one Pantone brand color across all six designs.
4. Finish: aqueous matte coating with a spot UV product name.
5. Result: consistent brand color across the line at a low unit cost, with fine detail for Supplement Facts panels.

See supplement boxes.

Common mistakes with offset artwork

1. RGB images left in files, which shift when converted.
2. Unnamed spot colors or duplicate Pantone names, creating extra plates.
3. Small text in four-color black, which blurs if registration shifts.
4. Excessive ink coverage in dark areas, causing drying problems.
5. Missing bleed.
6. Finish layers not set to overprint.

Sheetfed presses and sheet sizes

Most packaging offset printing is done on sheetfed presses, which print individual sheets rather than a continuous roll. Press size determines the largest sheet that can be printed, and sheet size determines how many cartons fit on one sheet. Large-format presses print big sheets that hold many cartons at once, which is one reason offset becomes so economical at volume. Smaller presses suit smaller jobs and cartons.

A typical carton press has several printing units in a row, one for each color, often followed by a coating unit. Six-color and seven-color presses are common, allowing CMYK plus one or two spot colors and an inline coating in a single pass. This is why offset can combine photographic images with precise brand colors and a protective coating so efficiently.

Screening: how images become dots

Offset presses print solid ink or no ink; there is no "half" ink. To create tones and photographs, images are broken into tiny dots of varying size or spacing, a process called screening. Conventional (AM) screening uses evenly spaced dots that vary in size. Stochastic (FM) screening uses tiny dots of the same size placed at varying density, which can reproduce fine detail and smooth tones and avoid patterns. Hybrid screening combines both approaches. The screening method is chosen by the printer, but it explains why offset can render skin tones, product photos and subtle gradients so well.

Inline coatings

Many offset presses apply a coating in the final unit as the sheet passes through:

• Aqueous coating is water-based, dries quickly and protects against scuffs. It is the most common choice for cartons.
• UV coating cures under ultraviolet light and gives a higher gloss and stronger protection.
• Varnish is applied like an ink, either across the whole sheet or as a spot effect.

An inline coating protects the print during die-cutting, folding, gluing, packing and shipping. If a lamination, foil or spot UV is planned, the coating must be compatible, so tell your supplier about every finish when requesting a quote.

Color standards and calibration

Consistent offset color relies on calibrated presses, controlled ink densities and agreed standards. Many printers work to recognized standards for printing conditions and gray balance, and use color bars on every sheet to measure density and color with instruments during the run. For brand owners, the practical points are simple: supply Pantone references for critical colors, approve a proof or press sample, and keep the approved sample as the reference for reorders. When the same carton is reprinted months later, the printer measures against that reference to keep colors consistent.

Grain direction and folding

Paperboard has a grain, the direction in which most fibers are aligned. Board folds more cleanly across some directions than others and is stiffer in one direction. Printers plan the layout of cartons on the sheet so the grain runs in the best direction for the carton's strength and folding. This affects how many cartons fit on a sheet and therefore price. It is another reason why carton size, board choice and sheet layout are planned together rather than separately.

Drying, setoff and curing time

Offset inks dry through absorption and oxidation. Printed sheets need time to dry before they are die-cut, folded and glued. If sheets are stacked too soon, wet ink can transfer to the back of the sheet above, a problem called setoff. Printers manage this with spray powders, coatings, UV-curing inks and drying time. Rushing a job can increase the risk of setoff or scuffing, so realistic timelines help quality as well as the schedule.

Offset for rigid box wraps

Rigid boxes are made by wrapping printed paper around greyboard. The wrap paper is usually printed by offset, which gives sharp images and accurate colors on thin, smooth papers. The printed wrap is then laminated or coated if needed, cut and glued around the board. Because wrap papers are thinner than carton board, folding and wrapping around corners must be considered in the artwork: designs that run across edges need precise alignment, and very dark colors may show slight cracking at tight corners unless the paper is laminated.

What to look for at a press check

A press check lets you see sheets as they come off the press and approve color before the full run. If you attend one, in person or by video:

• View sheets in standardized lighting rather than under room lights.
• Compare key colors against your Pantone references and approved proof.
• Look at skin tones, product photos and neutral grays.
• Check solids for evenness and look for streaks or spots.
• Confirm text, barcodes and small details are sharp.
• Remember that coatings and laminations slightly change color and gloss.

Press checks are most valuable for first runs and color-critical products. For reorders, the approved sample from the first run is usually enough.

Keeping color consistent over years

Brands that reorder the same cartons for years need consistent color across many runs. Keep an approved, signed sample from each product and store it away from light. Share it with your supplier at every reorder. Use the same board grade and coating, because changes in board brightness or coating alter how colors appear. If you change suppliers, provide the approved samples and Pantone references, and request a proof before production.

Offset artwork checklist

• CMYK artwork with spot colors named exactly as Pantone references.
• Images at least 300 ppi at final size.
• Rich black for large dark areas and 100% black for small text.
• Bleed and safe zones applied to the correct dieline.
• Finishes on separate layers named clearly.
• Barcodes in 100% black on a light background, with quiet zones.

Offset for multi-product ranges

Offset is especially efficient for brands with many products in the same carton size. Several designs can be printed on the same sheet, sharing setup costs, as long as quantities line up. A skincare range with six products, for example, might print all six cartons together, with quantities balanced across the sheet. Planning ranges this way can lower unit costs significantly compared with printing each product separately.

Offset and metallic inks

Metallic inks, such as gold and silver, can be printed by offset. They give a soft shimmer rather than the mirror-like brightness of foil, but they are less expensive and can be printed in fine detail. Metallic inks work best on coated boards and can be combined with coatings for extra sheen. Printing CMYK over metallic ink, or on metallic board, creates colored metallic effects.

Offset lead times

Offset involves platemaking, printing, drying, finishing, die-cutting and gluing. A typical carton job takes longer than a digital one, especially when finishes are added. Plan lead times early, especially for launches and seasonal products. Once plates and dies exist, reorders move faster.

Offset sustainability considerations

Offset inks and coatings are designed for paperboard recycling, and printed cartons are widely accepted in paper recycling programs. Efficient sheet layouts reduce board waste, and plates can be recycled. Choose recycled or certified board, aqueous coatings and moderate ink coverage where sustainability is a priority. Combining products on shared sheets also reduces waste by using each sheet fully.

Offset printing FAQ for designers

Designers often ask whether to convert spot colors to CMYK for offset. Keep brand-critical colors as spot colors if the budget allows an extra printing unit; otherwise, convert them carefully and approve a proof. Avoid mixing spot and process versions of the same color in one design, which can cause visible differences.

When to move from digital to offset

As volumes grow, brands often move from digital to offset. A common trigger is when a single design reaches quantities where offset's lower per-unit cost outweighs its setup cost. Ask your supplier to quote both methods at your expected quantities; the crossover point varies by carton size, colors and finishes.

Specification checklist for offset cartons

• Board grade and caliper.
• Carton style and dieline.
• Colors: CMYK plus any spot colors, with Pantone references.
• Coatings, laminations and finishes.
• Quantities per design, so sheets can be planned.
• Proof type: digital, printed or press check.

More offset FAQ

Is offset worth it for small runs?

For small runs, digital printing is usually more economical. Offset becomes competitive as quantities grow.

Quick decision guide: is offset right for this job?

How to brief us on an offset carton job

Offset jobs are planned around sheets and quantities. Send:

• Carton style, size and board. Or the product, and we will recommend.
• Number of designs and quantities. So we can plan sheets efficiently.
• Colors. CMYK and any Pantone spot colors.
• Finishes. Coatings, laminations, foil, spot UV, embossing, windows.
• Timing. Offset needs time for plates, drying and finishing.

Send what you have, even if some answers are rough. Our specialists reply within one business day with recommendations, a price estimate and next steps, and every order includes free design help and a 3D proof before anything goes to production.

Carton prices at offset quantities

Offset lithography is at its best on paperboard cartons in larger runs. Estimated unit prices for full-color cartons at volume:

A dash means the quantity is below that style’s minimum. Prices are estimates from our published model; the actual print process is chosen for your run length and design.

How to order offset printing

1. 1Request a quote

   Tell us the style, size, quantity and artwork you have. Use the form or the live estimator.

2. 2Free design & dieline

   We send a dieline for your exact size, check your artwork and help with layout at no charge.

3. 3Approve your proof

   Review a digital 3D proof (and an optional physical sample) before anything is printed.

4. 4Production & QC

   Your boxes are printed, finished, die-cut and inspected against the approved proof.

5. 5Delivered to your door

   Shipped flat-packed with tracking to any address in the contiguous US.

Written and reviewed by the CustomPacka Packaging Team · Updated October 21, 2026