The Bulk-Discount Myth

Slovenia's 3.96-L Persil is €6.06/L. The 2.25-L is €12/L — same brand, same shelf, double the price per litre for a smaller bottle.

Per-litre gap, same brand: 2×
Markets in the data: 8
Annual cost to ignore it: €60

Slovenia — Persil: €/litre by pack size

Slovenia — Persil: €/litre by pack size
Label	Value
1.8 L	7.33
2.25 L	12
2.475 L	10.9
2.97 L	10.1
3.96 L	6.06
5.94 L	10.77

Source: Sivix, selected products from the story

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21 April 2026

Everyone knows the biggest bottle is the best deal. In Europe's laundry aisle, nobody told the retailer. A 3.96-litre bottle of Persil in Slovenia runs €23.99 — €6.06 a litre, as cheap as Persil ever gets. The 2.25-litre bottle next to it is €26.99 — €12 a litre. Same brand, same shelf, double the per-litre price for a smaller bottle.

What the data shows

Across four markets where we can plot the full pack-size curve for a single brand, the "bulk discount" rule holds only in parts — and often breaks dramatically.

Slovenia — Persil (470+ records, 2025-06-26 to 2026-04-06):

Pack	€/litre	Records
1.8 L	€7.33	73
1.98 L	€7.36	90
2.25 L	€12.00	76
2.475 L	€10.90	70
2.97 L	€10.10	23
3.6 L	€10.55	53
3.96 L	€6.06	53
5.94 L	€10.77	8

Persil's shelf is a roller-coaster. The 3.96-litre bottle is the per-litre bargain. The 2.25-litre next to it is almost twice as expensive per litre. The 5.94-litre family pack — the biggest bottle on the shelf — is more expensive per litre than the 3.96. Bigger is not always cheaper.

Slovenia — Ariel (447 records): the 1.8-litre bottle is cheapest per litre at €8.03, with the 2.7-litre at €11.63 — 45% more per litre than the mid-pack. The 3.87-litre bulk bottle comes in at €10.18/L, still dearer than the 1.8.

Lithuania — Ariel: 1.35 L €8.04, 1.8 L €5.97, 2.7 L €9.26. Middle wins; the family pack is the most expensive per litre on the shelf.

Croatia — Persil: 1.98 L €7.45, 2.97 L €8.08, 3.96 L €5.05 (thin data, 3 obs), 2.7 L €9.13. The 2.7 L is 81% more per litre than the 3.96 L sibling.

Where bulk does work: Finland — Omo. 0.92 L at €8.47/L, 1.84 L at €6.33/L — the larger bottle is genuinely 25% cheaper per litre. This is the exception.

Why this happens

Pack-size pricing is a deliberate merchandising tool. Retailers know shoppers assume bigger equals cheaper; they also know most shoppers don't actually check the per-litre tag. So they price the "family pack" as a premium tier — the halo product that implies the brand is prestigious — and park the real value in a mid-size bottle that doesn't trigger the premium instinct.

Persil's 3.96-litre bottle in Slovenia at €6.06/L looks like the right call on every shelf-tag comparison — until you notice it's competing with the 2.25 L at €12/L in the same brand line. That's not a supply-chain explanation. It is a pricing strategy.

What it means for you

Before reaching for the biggest bottle, check the per-litre sticker. The European laundry aisle is full of examples where the middle-size bottle is the bargain and the "family pack" is the trap. A Slovenian household reaching for Persil 2.25 L on habit pays roughly €6 more per litre than the sibling 3.96 L. Across a year of typical weekly washing that's about €60, for no reason but pack-size optics.

Croatia — Persil: €/litre by pack size

Croatia — Persil: €/litre by pack size
Label	Value
1.98 L	7.45
2.7 L	9.13
2.97 L	8.08
3.96 L	5.05

Source: Sivix, Croatia shelf prices 2025-06-26 to 2026-04-07

Data source: Based on 13,500+ price records across 41 brand-by-pack-size cohorts in eight European markets between 2025-06-26 and 2026-04-07. Each cohort has at least five observations. Data reflects real shelf prices as reported at time of purchase.

Products referenced in this story

Real shelf prices as reported by Sivix contributors. Tap any product to see current prices.

Sweet spot — €6.06/L

Persil Gel Regular 88 washes 3.96 L

SI · View on Sivix →

Roller-coaster peak — €12.00/L

Persil Color 44 washes 2.25 L

SI · View on Sivix →

Where bulk works — €6.33/L

Omo Color 1.84 L

FI · View on Sivix →

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