A reusable product needs to be used enough times to justify the resources invested in making it. The answer depends on the comparison: what service is delivered, how the product is cleaned and transported, and how many uses it actually achieves.

UNEP’s 2021 synthesis of life cycle evidence encourages a shift from single-use products towards reusable alternatives. For a particular system, a transparent calculation helps identify the conditions that must hold. The example below teaches the arithmetic; it is not measured evidence about cups, packaging or any brand.

Define an equal service

Imagine two hypothetical containers delivering the same quantity of a product with the same protection and hygiene performance. Compare one completed delivery in each system. Include manufacturing, relevant transport, cleaning and end-of-life treatment within consistent boundaries. Product contents are assumed identical and unaffected in this simplified example.

Set out the illustrative assumptions

Assume a reusable container has a fixed climate impact of 2.0 kg CO2e, covering its manufacture, initial distribution and final treatment. Each completed use adds 0.04 kg CO2e for washing and return logistics. The single-use alternative causes 0.14 kg CO2e per completed delivery over the corresponding life cycle.

These numbers are invented for teaching. They are not emission factors and must not be used to make a real product claim. CO2e expresses greenhouse gases on a common climate-impact basis; it does not measure every environmental effect.

Calculate the break-even point

After n uses, the reusable option’s average impact per delivery is 2.0/n + 0.04 kg CO2e. Its impact is lower than the single-use alternative when 2.0/n + 0.04 < 0.14. Rearranging gives n > 20.

At 10 uses, the average is 0.24 kg CO2e per delivery. At 20 uses, both options equal 0.14. At 50 uses, the reusable average is 0.08. Under these assumptions, the first whole number of uses giving a lower result is 21.

Test the assumptions that could change the decision

If washing and return logistics instead add 0.09 kg CO2e per use, break-even moves to 40 uses and a lower result begins at 41. If that recurring impact reaches or exceeds 0.14, no number of uses makes the reusable option lower in this simple model with a positive fixed impact.

Loss and breakage matter because a container’s technical capacity is not its achieved lifetime. A fleet assessment should allocate impacts from all containers purchased, including early losses, across the total service actually delivered. Do not report only the best-performing containers.

Use the result responsibly

For a real project, collect data on return rates, completed cycles, cleaning loads, energy sources, transport and replacements. Test plausible ranges. Assess other relevant impacts, such as water use and pollution, rather than treating a climate result as an overall environmental verdict.

This screening calculation is not a complete life cycle assessment or proof of conformity with ISO standards. ISO 14040 and ISO 14044 provide the broader LCA framework and requirements; consult the applicable full standards when planning a formal study.

Sources and further reading

UNEP (2021): Addressing Single-Use Plastic Products Pollution using a Life Cycle Approach; official overviews of ISO 14040 and ISO 14044. Continue with circularity and environmental impact and our guide to reuse systems.

Published 4 October 2026. All numerical inputs are hypothetical.