Tesco vs Sainsbury's: Which UK Supermarket Is More Ethical?

Tesco vs Sainsbury's: Which UK Supermarket Is More Ethical?

Between them, Tesco and Sainsbury's take roughly four of every ten pounds spent in British grocery stores. They sit in millions of pension portfolios, often without the holder knowing. So the question of which is the more ethical business is not abstract. It shapes what shoppers fund at the till and what savers fund through their retirement.

The honest answer is that neither is clean, and the two firms fail in different places. Tesco is the more dramatic profile: genuinely strong on the environment, genuinely poor on corporate integrity. Sainsbury's is steadier, with fewer peaks and fewer scandals.

This comparison uses the Mashinii scoring system, which rates companies from -100 to +100 across 11 values. A score is built only from verified adverse records. A zero does not mean a company behaved well. It means we found no confirmed wrongdoing, which often reflects thinner evidence rather than innocence.

How the two supermarkets score

The table below sets the Tesco score against the Sainsbury's score across all 11 values.

Read across the rows and a pattern emerges. Tesco posts the higher highs and the lower lows. Sainsbury's clusters near the middle, positive where Tesco is negative on integrity, neutral where Tesco shows verified problems.

Where Tesco pulls ahead: environment and health

Tesco's strongest score is Planet-Friendly Business at +40, ahead of Sainsbury's at +20. As the largest UK grocer, Tesco has the scale to set emissions targets, push suppliers on packaging, and report against them. Its Zero Waste & Sustainable Products score of +30 reflects measurable progress on food-waste redistribution and plastic reduction, where Sainsbury's records a zero.

On Better Health for All, Tesco scores +30 against +20. Both retailers run reformulation programmes and promotion controls on high-fat, salt and sugar products. Tesco's lead here is narrow rather than decisive.

These are real strengths. A buyer who weights climate and health above all else would lean toward Tesco on the evidence.

Where Tesco falls down: integrity and data

The case against Tesco sits in two values. The first is Honest & Fair Business, where Tesco scores -30 against a positive +20 for Sainsbury's. This reflects the 2014 accounting scandal, in which Tesco overstated its profits by around a quarter of a billion pounds, triggering investigations and a deferred prosecution agreement. The episode left a lasting mark on how the firm's governance is read.

Supplier-payment disputes compound the picture. The Groceries Code Adjudicator, the regulator that polices how supermarkets treat suppliers, found in 2016 that Tesco had delayed payments to suppliers in breach of the code. That finding feeds Tesco's Fair Trade & Ethical Sourcing score of -30. Sainsbury's sits at zero on the same value, with no equivalent regulatory finding on record.

The second weak point is Safe & Smart Tech at -50, Tesco's worst score and the single widest gap between the two firms. Tesco operates the Clubcard, one of the largest consumer-data programmes in the country, and the score reflects verified concerns over how that data is collected and used. Sainsbury's, which runs its own Nectar scheme, scores zero here, which signals thinner evidence rather than a clean bill.

Where Sainsbury's is steadier

Sainsbury's does not win on any single dramatic measure. Its advantage is consistency. It is positive on integrity, neutral on sourcing, and avoids the data penalty that drags Tesco down.

On Fair Pay & Worker Respect, Sainsbury's scores -10 against Tesco's -20. Both have faced living-wage campaigns and equal-pay claims from store staff, but Sainsbury's was an early adopter of the real Living Wage commitment for its directly employed workers, which softens its score relative to Tesco.

Sainsbury's also edges ahead on Respect for Cultures & Communities at +25 to +20, reflecting community and charity programmes without the offsetting controversies that pull Tesco's wider profile down.

The shared failings

Neither firm escapes criticism on animal welfare. Both score -20 on Kind to Animals, tied to sourcing of intensively farmed meat, eggs and dairy across own-label ranges. Campaign groups have repeatedly named both retailers over chicken stocking densities and farm conditions.

Both also score zero on Fair Money & Economic Opportunity and No War, No Weapons. Those zeros mean no verified adverse record surfaced. They are not endorsements, and an investor should treat them as gaps in the evidence rather than proof of good conduct.

So which is more ethical?

There is no single winner. If you prioritise climate and waste reduction, Tesco's +40 and +30 scores make the stronger case. If you prioritise honest governance and fair treatment of suppliers, Sainsbury's clears a bar Tesco does not, given the accounting history and the regulator's payment finding.

For most ethically minded UK savers, the integrity gap is the one that matters. A business that overstated its profits and was found to have squeezed its suppliers carries a governance risk that a marginally better recycling rate does not offset. On that reading, Sainsbury's is the safer ethical hold, while Tesco is the better environmental one. The two judgments do not resolve into a tidy verdict.

The deeper point is that "ethical supermarket" is not one question but eleven. The right answer depends on which values you weight, and your portfolio almost certainly holds both.

See how your own holdings score

If Tesco or Sainsbury's sits in your pension or ISA, you can see the full breakdown behind these numbers. Run your portfolio through the Mashinii audit to surface every holding's record across all 11 values, or look up any company directly through company search.

For wider context, see our ranking of the most ethical LSE companies in 2026 and our guide to ethical investing in a UK pension.