Buying Refills at Big Green Smile: What Is the Real Cost per Wash?

A five-litre refill can look economical beside a smaller bottle, but litres alone do not tell you what each wash will cost. Concentration, the dose your laundry needs and the charges on a small order can change the result. At Big Green Smile, start with a familiar product, calculate the number of usable doses, then compare the whole delivered basket.

Compare the same formulation before comparing pack sizes

Write down the full product name, fragrance, concentration and intended use. A five-litre everyday laundry liquid and a five-litre concentrated version need not provide the same number of washes. Fabric conditioner is also a separate purchase from detergent, even when both bottles sit in the laundry section.

Big Green Smile lists both concentrated laundry refills and other large-format cleaning products. Use the individual product instructions to decide which belongs in your comparison. Check whether it suits the fabrics you wash: the retailer’s Ecover Concentrated Non-Bio Laundry Liquid Refill 5L listing excludes wool and silk. A low cost per wash is irrelevant if the formula is unsuitable for your washing.

Work out cost per wash using your actual dose

The useful calculation is: product cost ÷ number of washes at the recommended dose for your load. Convert litres to millilitres first. Five litres is 5,000ml; divide that by the dose in millilitres, rather than assuming every bottle delivers its largest advertised wash count in every household.

For example, Big Green Smile’s concentrated Ecover non-bio refill instructions give approximately 35ml for a standard load and 50ml for a larger or heavily soiled one. Those doses produce roughly 142 complete washes or 100 washes respectively from five litres. Check the current pack’s guidance for load size, soiling and water hardness before choosing the figure for your calculation.

Illustrative calculation, not a current offer: a hypothetical £30 refill would cost about 21p per wash at 142 washes, but 30p at 100 washes. The bottle price has not changed; the amount used has. Apply the same calculation to a smaller bottle before deciding which is better value.

Use the measure specified for the product. A cap from an old bottle or an unmeasured pump stroke is not automatically the right dose. Do not reduce the recommended amount simply to make a price comparison look better.

Add delivery and the small-order surcharge

At the time of checking on 1 November 2026, Big Green Smile’s delivery page lists £4.95 delivery for UK orders under £55 and free shipping for orders over £55. It also lists a separate small-order surcharge, calculated on goods after discounts and excluding delivery:

• Below £15: £8.
• £15 to below £25: £6.
• £25 to below £34.95: £4.
• £34.95 or more: no small-order surcharge.

These are different charges. Check the final basket, particularly at the £55 boundary or after applying a discount. A hypothetical £30 order would total £38.95 with the stated £4 surcharge and £4.95 delivery. If that order consisted only of the example refill, its delivered cost would be about 27p per wash at 142 washes or 39p at 100.

A planned top-up of something you already use may help spread delivery costs. An unwanted extra still costs money. Compare the amount you will actually pay for each basket, not just the charge that disappears when you cross a threshold.

For surface cleaners, compare usable solution

Laundry wash counts do not translate directly into cleaning-spray refills. First establish whether a refill is ready to use or needs dilution for the job you have in mind.

For instance, Big Green Smile’s Ecover All Purpose Cleaner Lemongrass & Ginger Refill 5L instructions specify 25ml in about five litres of warm water for mopping. On that particular basis, the refill supplies 200 measured bucket doses. That does not mean 200 rooms: floor area, dirt and how often you replace the water vary. Compare the cost per correctly prepared bucket between suitable products, then consider how often you use one.

Follow each product’s own surface, dilution and rinsing instructions; do not transfer one cleaner’s recipe to another. Buy the refill that matches the original labelled container and use any refill system as directed. Keep instructions available, and avoid an unlabelled bottle whose contents could later be mistaken for something else.

Buy an amount you can store and finish

Count your household’s typical weekly washes before choosing a large pack. At four washes a week, 100 doses represent roughly 25 weeks of use. That is a planning estimate, not a shelf-life claim: check the product’s storage instructions and any expiry or period-after-opening information.

Consider where the container will stand, whether you can lift and pour it comfortably, and whether a compatible dispenser costs extra. Keep cleaning products securely stored according to their labels and out of children’s reach. If you are trying a fragrance or formulation for the first time, a smaller bottle can be a sensible way to avoid being left with several litres you do not want.

Compare the final basket with a relevant alternative

Before paying, check the Big Green Smile discount code page for a potentially applicable offer, then read its exclusions and confirm the checkout total. Do not assume a code combines with bulk pricing or keeps the basket above a delivery or surcharge threshold.

Ethical Superstore is a useful comparison for this task because it also lists Ecover’s concentrated non-bio 5L refill and other household refills. Use the same formulation and quantity when comparing, and check the Ethical Superstore discount code page alongside that retailer’s current delivery charge. The better purchase is the suitable quantity with the lower total cost for the washes or cleaning jobs you will actually get from it.