Resin Infusion Calculator for Composite Layups

Resin Infusion Calculator

Estimate mixed resin for vacuum infusion from laminate area, dry fiber stack weight, resin ratio, line loss, flow allowance, and pot life margin.

Named Infusion Presets

📏 Infusion Inputs

Use the combined dry stack weight for all plies in the infused zone.
0.58 means 0.58 resin mass units per 1 dry fiber mass unit.

Infusion Resin Estimate

Dry Fiber Stack

0
counted laminate mass

Laminate Resin

0
before plumbing loss

Total Mixed Resin

0
including line and flow loss

Pot Life Margin

0
usable working window

🧱 Infusion Planning Grid

0.45:1 Carbon target
Compact carbon stacks often plan lean resin ratios when the vacuum path is proven.
0.55:1 E-glass target
A useful starting point for stitched glass panels with clean flow media.
6-14% Flow allowance
Covers resin retained in peel ply, mesh, grooves, and wet feed paths.
25% Pot margin
Reserve working time for degassing, clamp changes, leaks, and slow fronts.

📊 Reference Tables

Reinforcement StackTypical Resin:FiberFiber Weight SharePlanning Use
Carbon cloth stack0.40 to 0.5266% to 71%Thin panels, plates, fairings
E-glass stitched fabric0.50 to 0.6262% to 67%Boat panels, covers, molds
Aramid / Kevlar0.55 to 0.7059% to 65%Guard parts and impact skins
Cored grooved panel0.60 to 0.7856% to 63%Decks, hatches, sandwich skins
Tooling or mold skin0.58 to 0.7557% to 63%Flanges and heavier mold areas
Line SizeApprox Hold-UpPer 10 ftUse In Calculator
1/4 in ID tube0.49 fl oz/ft4.9 fl ozSmall parts and short feed lines
3/8 in ID tube1.10 fl oz/ft11.0 fl ozCommon feed and spiral wrap estimate
1/2 in ID tube1.96 fl oz/ft19.6 fl ozLong manifolds and higher flow demand
10 mm ID tube78.5 ml/m785 ml / 10 mMetric feed line planning
Vacuum / Flow ConditionExtra ResinWhy It ChangesPlanning Note
Flat coupon, short path3% to 6%Low mesh and peel-ply retentionBest after a successful test coupon
Standard flat panel8% to 12%Normal feed, peel ply, and mesh hold-upGood default for first full panel
Grooved core panel12% to 18%Core kerfs and perforations hold resinVerify core absorption separately
Deep mold or flange14% to 22%Edges and resin breaks retain more resinWatch dry corners and slow fronts
Project TypeTypical AreaStack WeightStarting Setup
Carbon hatch8 to 16 sq ft400 to 600 gsm0.45 ratio with short lines
Boat deck insert20 to 50 sq ft700 to 1000 gsm0.65 ratio plus core allowance
RC wing skin0.5 to 2 m²150 to 300 gsmSmall bucket and long pot life
Tooling flange10 to 30 sq ft600 to 900 gsmExtra flow allowance at edges

💡 Infusion Tips

Dry stack check: If possible, weigh the cut reinforcement stack and use the calculator result as a cross-check against area-based mass.
Line loss check: The tubing volume is only part of the plumbing loss. Spiral wrap, cups, valves, and catch-pot wetting add extra retained resin.
Flow timing: Keep the fill time plus margin below the usable pot life. Warm resin and large buckets can shorten the practical window.
Ratio control: Add line and flow allowances after the laminate ratio so the target fiber content remains visible in the breakdown.
Safety note: Wear gloves, eye protection, and ventilation suited to the resin system. Follow the manufacturer mix ratio, vacuum bagging limits, pot life, exotherm limits, and maximum batch size. Do a leak check before opening the feed line.
Calculator results are planning estimates for resin infusion. Final demand depends on actual dry stack weight, compaction, fabric architecture, core absorption, flow media, tube volume, bag leak rate, resin temperature, and process timing.

Vacuum infusion require calculating the total volume of resin that will be required for a project. A common error in calculating the resin requirement is only calculating the resin necessary to soak the fiber. The fiber will absorb resin, but the peel ply and flow media will also consume resin.

If you dont account for the resin that these components consume in the calculation of the total volume of resin that will be infused into the laminate, the laminate will contain dry spots. These dry spots will cause the part to fail. To account for all of the resin that will be consumed by the vacuum infusion system, you must account for the resin that becomes trapped in the peel ply and flow media.

How to Calculate Resin Needed for Vacuum Infusion

Additionally, you must also account for the resin that remains in the feed lines, catch pot, and manifold. This resin that remains in the system is referred to as line loss. Line loss are a fixed number for each vacuum infusion system so that the amount of resin that is infused into the mold will reach every part of the mold.

One of the critical measurements for vacuum infusion is the resin-to-fiber ratio. The resin to fiber ratio is the amount of resin relative to the weight of the dry fiber. Using too much resin will result in a heavy part that is brittle when forced to flex.

Using too little resin will result in dry spots in the part that will make it weak. Because carbon fiber is tighter than fiberglass, the resin-to-fiber ratio will need to be leaner for parts that use carbon fiber. Additionally, if cored panels is used in the part, the amount of resin will need to be increased to allow the resin to soak into the cores.

To calculate the weight of the dry fiber that will be used in the part, you can weigh the fabric before it is placed onto the mold. This is the most accurate measurement of the dry fiber weight. Additionally, once you have calculated the dry fiber weight, the amount of resin that will be used will need to include an allowance for resin to flow through the mold to reach the vacuum brake.

It is better to have resin in the catch pot than voids in the skin of the part. The plumbing for the vacuum infusion system will also consume resin. The feed lines will be long and thin, and they will hold some of the resin that will be infused into the part.

If long feed lines are used in the infusion system, more resin will need to be mix into the system to compensate for the resin that will remain in the feed lines. The resin has a limited amount of time in which it will remain in its liquid state. This amount of time is referred to as the pot life of the resin.

The amount of time that the resin will remain usable will likely be less then the stated pot life of the resin. The time spent degassing the resin and the time it takes to fill the mold will use up some of the usable time of the resin. If the fill time is close to the stated pot life, the resin will begin to thicken.

Additionally, if the temperature in the infusion area drops, the resin will flow more slow. If the resin flows slowly, it may begin to harden before it reaches the end of the mold. Thus, you should of included some extra time in the infusion system to account for these issues.

For the infusions of large parts, use staged batching of the resin instead of batching the resin into one large batch. If one batch of all of the resin is mixed together, the chemical reaction will cause the resin to cook itself before it reaches the mold. By batching the resin into smaller batches that are mixed at different times, the temperature and viscosity of the resin will remain steady.

By accounting for the weight of the fiber, line loss, flow media, and the pot life of the resin, resin will flow steadily from the mold to each part of the mold. Alot of people forgets that the resin needs to flow smoothy. Its important to monitor the process.

Resin Infusion Calculator for Composite Layups

Author

  • Thomas Martinez

    Hi, I am Thomas Martinez, the owner of ToolCroze.com! As a passionate DIY enthusiast and a firm believer in the power of quality tools, I created this platform to share my knowledge and experiences with fellow craftsmen and handywomen alike.

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