3D Printed Part Annealing Shrinkage Calculator
How to estimate 3D-print annealing shrinkage
This annealing shrinkage calculator projects cooled dimensions from the part's original size, a linear expansion coefficient, and the difference between annealing and baseline temperatures. Use it to estimate whether a heat-treated print may affect a fit, tolerance, or assembly alignment.
Enter the measured dimensions and your coefficient assumption, then compare the predicted cooled dimensions with the tolerance you need. The footprint overlay and mini-game illustrate the model, but annealed test coupons remain the best way to calibrate a particular filament and process.
Why visualizing 3D-print annealing shrinkage helps
For an annealed 3D-printed part, the canvas overlays the original footprint with the calculated cooled footprint so the predicted contraction is visible as well as numeric. As you change the coefficient or temperature difference, the blue rectangle moves inside the gray outline. The caption repeats the dimensions in text for users who do not rely on the drawing.
Understanding annealing shrinkage in 3D-printed parts
This 3D-print annealing calculator uses a first-order linear model to estimate the cooled size of a printed part. The model treats the entered original dimension as , uses the temperature difference , and applies the supplied linear coefficient . The calculator uses for each entered axis, where is the projected cooled dimension. It also reports the percentage change, .
Annealing a fused-filament part can change more than its temperature. Reheating can relax print-induced stresses and, for polymers capable of crystallizing, can introduce structural changes that a simple thermal coefficient does not fully describe. The calculated figure is therefore a planning estimate, not a substitute for a measured process-specific shrinkage allowance.
The coefficient is especially important in this annealing estimate because it controls the scale of every predicted dimensional change. The calculator assumes that one constant linear coefficient applies across the entered temperature interval and to every axis. Actual behavior can vary with polymer formulation, print orientation, wall thickness, infill, moisture, restraint, and the heating and cooling profile.
Worked example: annealing a PLA bracket
For a printed bracket measuring 100 mm by 40 mm, an annealing temperature of 80 °C, a baseline temperature of 25 °C, and a coefficient of 100×10⁻⁶ /°C give . The calculator therefore projects cooled dimensions of 99.45 mm × 39.78 mm. In the footprint view, the blue rectangle is centered inside the gray original outline because the same factor is applied to length and width.
Annealing shrinkage comparison by coefficient
| Material | CTE (×10⁻⁶/°C) | Shrinkage over 60 °C |
|---|---|---|
| PLA | 100 | 0.60% |
| ABS | 80 | 0.48% |
| Nylon | 100 | 0.60% |
How to interpret the annealing shrinkage diagram
In the annealing shrinkage diagram, gray represents the entered room-temperature footprint and the semi-transparent blue rectangle represents the calculator's cooled footprint. Equal margins around blue indicate the model's uniform, isotropic scaling. A real print that shows unequal measured margins is exhibiting axis-dependent change that one shared coefficient cannot represent.
Limits of a 3D-print annealing shrinkage estimate
Annealing shrinkage depends on the full thermal history of a printed part, not only on the two temperatures in this form. Heating uniformity, dwell time, cooling rate, part geometry, supports, and local thermal gradients can all change a part's shape. This calculator assumes uniform temperature and uniform dimensional response, making it most useful as a straightforward initial estimate.
Filled and reinforced filaments can also behave differently from an unfilled base resin. Glass, carbon, mineral, or other fillers may alter expansion, constrain deformation, and create stronger directional effects. When a filament datasheet provides a relevant value, enter that value; otherwise, establish an effective coefficient from measured coupons made with the same filament and print settings.
Measure annealed parts only after they have returned to the baseline temperature used in the calculation. Calipers or other suitable metrology tools should be applied at consistent reference features, and several measurements can reveal whether one location or axis moves more than another. The result shown here is a uniform projection, so it should be compared with an average or critical-feature measurement rather than treated as a complete deformation map.
Dimensional stability is only one consideration when deciding whether to anneal a print. A heat cycle may be chosen for material or performance reasons, but it may also make a nominally accurate print unsuitable for a tight mating feature. Estimating the expected size change before the cycle helps identify where extra clearance, stock for machining, or a compensating CAD scale may be needed.
Some parts can continue changing as they equilibrate after heat treatment. If a component will be machined, bonded, or assembled to a close tolerance, record the time between annealing and measurement as part of the process. Repeating the same coupon test after a consistent stabilization period produces more useful compensation data than relying on a generic coefficient alone.
An iterative coupon workflow makes this annealing calculator more valuable. Print a small representative feature, record its dimensions, anneal it with the intended cycle, and measure it after cooling. Use the difference to refine the coefficient or to define a direct scale factor for later parts. This links the simple model to the behavior of your actual machine, filament, and oven.
Scaling a 3D-printed part after annealing tests
Although this tool applies one coefficient uniformly to the length, width, and optional height, annealed prints may not shrink equally along all three axes. Layer orientation, geometry, and gravity during heating can produce different measured changes in X, Y, and Z. When that happens, determine separate measured compensation factors for the affected axes rather than assuming the uniform preview is a complete prediction.
Some slicers and CAD tools support nonuniform scaling. Combining those controls with measured pre- and post-annealing dimensions can help target a final fit, but the compensation should be verified with another coupon or representative print. Critical assemblies benefit from recording the filament, orientation, fixture, and thermal cycle alongside the dimensions.
Annealing schedules and equipment for printed parts
An annealing setup should heat the printed part as evenly and repeatably as possible. Verify the actual chamber temperature with an appropriate thermometer rather than assuming a displayed setpoint is exact, and support shapes that could sag while soft. The temperature, dwell period, and cooling approach should follow the material supplier's guidance where available.
For annealed 3D prints, abrupt temperature differences can create gradients through the part and make the simple uniform model less representative. A repeatable ramp, hold, and cooling process is easier to calibrate than an uncontrolled cycle. Thick sections and complex shapes may require additional validation because their interior and exterior do not necessarily follow the same temperature history.
Measuring and compensating annealed dimensions
For 3D-print annealing compensation, begin with reference dimensions that can be measured consistently before and after the heat cycle. Calipers are useful for many linear features, while more complex parts may require a fixture, scan, or coordinate measurement process. Small coupon features near critical geometry can provide a practical indication of local change without sacrificing an entire production part.
Designing selected features oversize and machining them after annealing is another way to manage tight requirements. The calculator's percentage output can help estimate the likely dimensional allowance, but machining stock and tolerances should be chosen from measured behavior of the actual material and process.
Material-specific annealing shrinkage considerations
Each polymer and filament blend requires its own annealing investigation. A manufacturer may specify a recommended thermal range or may provide dimensional-change information, but pigments, fillers, moisture condition, extrusion history, and print settings can still change the outcome. Use the value entered in this calculator as a documented assumption, then update it when coupon measurements provide better evidence.
Reinforcement and color additives can alter how a printed part responds to heat. Treat a new color, brand, or filled variant as a potentially different material for shrinkage planning, especially when a part has critical dimensions. A measured coefficient from one filament should not automatically be transferred to another formulation.
Safety and handling during print annealing
Annealing 3D-printed polymers requires suitable ventilation, heat-safe handling, and equipment appropriate for the material. Avoid contaminating food-preparation equipment with plastics or residues, use heat-resistant gloves when moving hot fixtures, and follow the filament supplier's safety information. Keep softening parts supported so they do not deform under their own weight.
Before heat treating a complex print, consider how delicate features, bridges, and enclosed volumes will be supported. A dedicated, repeatable setup can improve both safety and dimensional consistency, which in turn makes the calculator's coefficient-based estimate easier to calibrate.
Advanced modeling of annealed print deformation
For 3D-printed annealing work that demands more detail than a uniform linear estimate, engineers may use measured material data and simulation to study temperature gradients, restraint, and shape change. Those approaches can model effects that this calculator intentionally leaves out, including nonuniform geometry and time-dependent behavior.
Empirical models can also be built from a controlled series of coupons annealed at different conditions. Such data may reveal how the effective shrinkage coefficient changes with a particular material and cycle. This calculator remains useful as a transparent linear baseline when a full process model is unnecessary.
Recording annealing shrinkage results
After calculating a 3D-print annealing estimate, use “Copy Result” to place the displayed cooled dimensions and percentage shrinkage on the clipboard for a lab notebook, spreadsheet, or slicer workflow. Pair those values with the filament, dimensions, orientation, and oven settings so future compensation decisions are based on traceable trials.
Related 3D-print process calculators
Estimate material usage with the Filament Usage Estimator, dry filaments before annealing using the Filament Drying Time Calculator, or gauge structural impacts in the Porosity Strength Calculator.
Annealing Drift Lab Mini-Game
Drag the heat throttle and tap corrective pulses to keep shrinkage within tolerance. Each run reflects your current α and ΔT inputs so the oven feel mirrors the calculator.
Aim for ΔL = α·L·ΔT while the oven fights back.
Idle — input values to sync the challenge.