“Bar soap is better for the planet” gets repeated often enough in sustainability content that it’s worth asking whether it’s actually been measured, or just assumed because bars come without a plastic bottle. It turns out this has been studied formally — through life-cycle assessment (LCA), the standardized method researchers use to add up a product’s environmental cost from raw material to disposal — and the gap between bar and liquid is larger than the packaging alone would suggest.

Here’s what the research actually found, and where the comparison is more nuanced than it first appears.

What Life-Cycle Assessment Actually Measures

An LCA doesn’t just look at what a product is packaged in. Done properly under ISO 14040/14044 standards — the international framework researchers use for this kind of analysis — it accounts for raw material sourcing, manufacturing energy, packaging production, transportation weight and volume, in-use water consumption, and end-of-life disposal, all added together into comparable environmental impact figures.

A widely cited LCA from the Institute of Environmental Engineering at ETH Zurich compared hand washing with liquid soap against bar soap across this full chain, rather than just packaging. The researchers found that liquid soap production generated roughly ten times the greenhouse gas emissions of bar soap production. Two factors drove most of that gap: liquid soap requires substantially more energy to manufacture its raw surfactant ingredients, and it requires far more energy to produce its packaging — the study found liquid soap packaging alone demands close to twenty times the energy of bar soap packaging.

Why the Gap Is Bigger Than “Plastic vs. No Plastic”

It’s tempting to assume the entire difference comes down to bottles, but the ETH Zurich analysis found packaging is only part of the story. Transportation is a second major factor: liquid soap is typically 70–90% water, and shipping that water in rigid plastic bottles adds substantial weight and volume compared to a compact, low-moisture bar. The same research found liquid soap distribution generated close to eight times the emissions of bar soap distribution, largely because trucks and cargo containers are moving mostly water rather than active cleaning ingredients.

A separate 2023 life-cycle study published in the peer-reviewed journal Sustainability, which modeled the full manufacturing value chain of bar soap under ISO methodology, reinforced a related point: even within bar soap production, packaging materials meaningfully affect the final environmental score, and the researchers specifically recommended recycled paper or biogenic packaging over plastic wherever bars are individually wrapped — meaning even bar soap doesn’t get an automatic pass if it’s shrink-wrapped in plastic.

Where Liquid Soap Actually Performs Better

The data isn’t one-directional, and it’s worth being accurate about that rather than only citing the numbers that favor bar soap.

Consumer usage studies referenced in the same body of research found people tend to use noticeably less liquid soap per single hand wash than bar soap by weight, and some liquid formats use less rinse water per use in certain washing behaviors. Chemical industry analysis group Ethical Consumer and other reviewers have also noted that the use phase — how much product and water someone actually uses per wash — can partially offset liquid soap’s production and packaging disadvantages if a bottle is used efficiently, refilled, or bought in bulk concentrate form rather than replaced with a new plastic bottle each time.

In other words, the picture is: bar soap has a substantially lower footprint in manufacturing, packaging, and transport, largely regardless of user behavior — while liquid soap’s environmental cost is more sensitive to how it’s used and purchased.

The Plastic Waste Piece, Specifically

Beyond carbon accounting, plastic waste is its own separate problem, since most bottled body wash containers are not reliably recycled in practice even when technically recyclable — contamination, mixed materials (pumps, caps, labels), and inconsistent municipal recycling infrastructure all reduce real-world recycling rates for personal care plastic specifically. Retailer sustainability reporting has put concrete numbers on the scale of this: cosmetics company Lush estimated that switching customers to solid shampoo bars prevented around 100 metric tons of plastic packaging in a single year, with solid body wash bars adding several more tons of prevented plastic on top of that.

Bar soap, particularly when packaged in paper or left unpackaged, sidesteps this problem structurally rather than depending on the end user recycling correctly.

What This Means for Choosing a Bar

Not every bar soap is equally low-impact, and “bar soap” alone isn’t the full sustainability story. A few things are worth checking:

• Packaging material — paper, cardboard, or unwrapped bars have a meaningfully lower footprint than bars individually shrink-wrapped in plastic film
• Ingredient sourcing — palm oil–derived soap bases carry their own well-documented deforestation and land-use concerns unless sourced from certified sustainable growers; coconut, olive, and other regionally sourced oils sidestep some of that risk
• Shipping distance and format — concentrated bars shipped in bulk, minimally padded packaging compound the transport advantage further
• Actual usage life — a bar that lasts longer per gram used effectively lowers its per-wash footprint further, similar to how liquid soap’s footprint improves with efficient use

Where PALFICAB Fits In

This is part of why our bars ship in plastic-free packaging rather than bottled formats — it’s a direct, structural way to avoid the packaging and transport-weight costs the research above consistently points to, rather than a symbolic gesture. It doesn’t make every environmental question about personal care products disappear, but on the specific, measured factors life-cycle researchers track — production energy, packaging, and shipping weight — the format itself does the heavy lifting.

Frequently Asked Questions

Is bar soap actually better for the environment than body wash, or is that just marketing? It’s been measured through formal life-cycle assessment research, not just assumed. Multiple studies, including an ETH Zurich analysis, found liquid soap products carry meaningfully higher production and packaging emissions than bar soap, largely due to raw ingredient energy use and plastic packaging production.

Does the water content in liquid soap actually matter environmentally? Yes — liquid soap is typically 70–90% water, which adds significant shipping weight and volume compared to a compact bar, increasing transportation-related emissions.

Is all bar soap automatically eco-friendly? No. Packaging matters even for bars — plastic-wrapped bars lose some of the advantage — and ingredient sourcing (like non-certified palm oil) can carry its own environmental concerns regardless of format.

Does using liquid soap efficiently close the gap with bar soap? It can partially offset the difference. Buying in bulk, refilling containers, and using less product per wash all reduce liquid soap’s footprint, though production-stage differences remain the larger factor in most life-cycle studies.

What packaging should I look for if I care about plastic waste specifically? Paper, cardboard, or unpackaged bar soap avoids most of the plastic waste problem structurally, without depending on whether the packaging actually gets recycled after use.

The Bottom Line

The bar-soap-is-greener claim holds up under actual life-cycle assessment, not just at the level of “no bottle needed” — the bigger drivers are manufacturing energy, packaging production, and the sheer weight of shipping water-heavy liquid formulas. That said, the comparison isn’t absolute: packaging material still matters within bar soap, ingredient sourcing carries its own environmental weight, and efficient use can narrow the gap on the liquid side. Format is a strong starting signal, not the whole answer.

This article summarizes published life-cycle assessment research for general educational purposes.

Sources referenced

• Witlox, K., Keller, R., Jungbluth, N. “A LCA Case Study of Hand Washing with Liquid and Bar Soap.” Institute of Environmental Engineering, ETH Zurich.
• Gaurav, G., et al. “The Environmental Impacts of Bar Soap Production: Uncovering Sustainability Risks with LCA Analysis.” Sustainability, 15(12), 2023.
• Lush plastic-waste-prevention estimates, reported via Chemical & Engineering News (C&EN), 2017–2018 solid product launch data.
• Earth911 and Ethical Consumer summaries of comparative bar vs. liquid soap life-cycle data.