Microplastic Laundry Shedding Calculator
Why microplastic shedding from laundry matters
Many everyday textiles—especially synthetic fabrics such as polyester, nylon, acrylic, and elastane blends—can release tiny fibers when they are washed. These fibers are a form of microplastic (commonly defined as plastic particles smaller than 5 mm). During a wash cycle, mechanical action (tumbling, agitation), water flow, and detergent can loosen fibers from yarns and seams. Some portion of those fibers may pass through household plumbing and wastewater treatment, and a fraction can reach rivers, lakes, and oceans (or accumulate in sewage sludge depending on local treatment practices).
This calculator provides a directional estimate of how many grams of microplastic fibers your laundry could shed per wash based on a few major drivers researchers frequently identify: load mass, fabric type, and washer style. It is intended for learning, comparison, and “what-if” scenarios—not for compliance reporting or precise measurement.
What the calculator estimates
The output is an estimated mass of fibers released in a single wash:
- Estimated shedding (g/wash): the modeled grams of microfibers generated during the cycle
- Per-kilogram intensity (g/kg) (implicit): the estimated grams per kilogram of laundry for the chosen conditions
Because shedding varies widely across garments and conditions, treat the number as a midpoint-style estimate. The best use is to compare scenarios (e.g., synthetic vs blend, front-load vs top-load) using the same load weight.
Inputs and factors
1) Load weight (kg)
This is the total mass of clothing/textiles placed in the washer (dry or roughly dry). Larger loads tend to produce more total shedding because there is more material present. However, real-world shedding per kg can go up or down depending on overloading, underloading, and friction conditions.
2) Fabric type
The calculator uses a fabric factor to represent typical relative shedding:
- Synthetic: highest modeled shedding (factor ≈ 1.0)
- Blend: moderate modeled shedding (factor ≈ 0.6)
- Natural fiber: lowest modeled microplastic shedding (factor ≈ 0.2)
Note: natural fibers (cotton, wool) are not plastics, but they can still shed fibers. This calculator focuses on microplastic fiber release, so natural fibers are treated as lower contribution to microplastics specifically (not “zero overall fiber shedding”).
3) Machine type
Washer mechanics affect friction and abrasion. A simplified machine factor is applied:
- Front-load: gentler tumbling (factor ≈ 1.0)
- Top-load: more vigorous agitation (factor ≈ 1.2)
Formula used
The model is a multiplicative estimate:
R = W × B × F × M
Where:
- R = estimated microplastic release (grams per wash)
- W = load weight (kg)
- B = base shedding rate (grams per kg per wash). Here: 0.5 g/kg
- F = fabric factor (unitless)
- M = machine factor (unitless)
MathML version of the same equation:
The chosen constants are intentionally simple to keep the calculator understandable. Real shedding can span orders of magnitude depending on garment construction (fleece vs tightly woven), age, and washing conditions.
Worked example
Scenario: You wash a 6 kg load that is mostly synthetic in a top-load washer.
- W = 6 kg
- B = 0.5 g/kg
- F (synthetic) = 1.0
- M (top-load) = 1.2
Calculation: R = 6 × 0.5 × 1.0 × 1.2 = 3.6 g per wash
How to think about it: if you did that same wash twice per week, the modeled release would be about 7.2 g/week (3.6 × 2), or roughly 374 g/year (7.2 × 52). Those rollups amplify uncertainty, so use them mainly to compare habits, not as a precise annual total.
Interpreting your results
Use it for comparisons
The estimate is most useful when comparing choices under similar conditions:
- Switching from top-load to front-load reduces the machine factor in this model.
- Washing more blends or natural fibers reduces the fabric factor for microplastics.
- Reducing load weight reduces total shedding, though very small loads may increase friction in some machines in reality.
What a “high” number means here
“High” is relative. A high estimate typically indicates a combination of (a) heavier loads, (b) more synthetic content, and/or (c) more aggressive washing mechanics. If you want to reduce shedding, consider: gentler cycles, lower agitation, full-but-not-overloaded loads, and microfiber-capture solutions (filter, bag, or laundry ball) where appropriate.
Comparison table (example scenarios)
The table below illustrates how the model responds to different inputs for the same 5 kg load (B = 0.5 g/kg):
| Scenario | W (kg) | Fabric (F) | Machine (M) | Estimated R (g/wash) |
|---|---|---|---|---|
| Synthetic + top-load | 5 | 1.0 | 1.2 | 5 × 0.5 × 1.0 × 1.2 = 3.0 |
| Synthetic + front-load | 5 | 1.0 | 1.0 | 5 × 0.5 × 1.0 × 1.0 = 2.5 |
| Blend + front-load | 5 | 0.6 | 1.0 | 5 × 0.5 × 0.6 × 1.0 = 1.5 |
| Natural fiber + front-load | 5 | 0.2 | 1.0 | 5 × 0.5 × 0.2 × 1.0 = 0.5 |
Assumptions & limitations
- Base rate is a simplification: The model uses a single base shedding rate (0.5 g/kg/wash). Published findings vary widely by fabric, garment construction, and measurement methods. Your true value could be much higher or lower.
- Fabric categories are coarse: “Synthetic,” “blend,” and “natural” are broad. A polyester fleece, a tightly woven nylon shell, and a polyester-cotton tee can behave very differently.
- Cycle settings not included: Water temperature, cycle length, spin speed, detergent type, and whether you use a delicates bag can materially change shedding.
- Garment age and wear not included: New vs aged items, pilling, and damage can increase fiber release.
- Capture and treatment not modeled: Some households use microfiber filters; wastewater treatment removal rates differ by location; captured fibers may end up in sludge rather than waterways.
- Output is per wash, not environmental fate: The calculator estimates fibers released from textiles during washing, not how much reaches oceans or organisms.
References (for further reading)
For users who want to dig deeper into microfiber shedding and measurement variability, these sources are a good starting point:
- Henry, B., Laitala, K., & Klepp, I. G. (2019). Microfibres from textiles: A literature review. (Reviews variability and methods.)
- De Falco, F. et al. (2019). Studies on microfiber release during domestic washing. (Multiple papers explore drivers like fabric structure and washing conditions.)
- UNEP / IUCN reports on primary microplastics and microfiber pathways. (Context on sources and pathways.)
These references are provided for context; the calculator’s simplified factors are intended for scenario comparison rather than reproducing any single study’s measured rate.