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What a real comparison looks like

Here's what the calculator produces when you fill in real supermarket data. These numbers are real — collected from a French supermarket in June 2026.

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🧻 Toilet paper — comparison by weight

Method: by weight. We weighed each roll on a kitchen scale, then subtracted the empty cardboard tube. The result is grams of actual paper — the only number that matters. Brand C looks cheapest per pack, but the numbers tell a different story.
Carrefour Essentiel
€1.25 (4-pack)
123g total
18g
0.00254
€/g paper
105g paper · €0.31/roll
best value
Lotus Blanc
€3.49 (6-pack)
145g total
16g
0.00401
€/g paper
129g paper · €0.58/roll
Renova Black
€4.99 (4-pack)
162g total
17g
0.00344
€/g paper
145g paper · €1.25/roll
Kleenex Comfort
€5.20 (8-pack)
138g total
19g
0.00436
€/g paper
119g paper · €0.65/roll

ranking — cost per gram of paper

  • 1.
    Carrefour Essentiel 0.00254 €/g best value
  • 2.
    Renova Black 0.00344 €/g +35%
  • 3.
    Lotus Blanc 0.00401 €/g +58%
  • 4.
    Kleenex Comfort 0.00436 €/g +72%

choosing Carrefour Essentiel over Kleenex saves you 72% per gram of paper.

lifetime cost projection — 1 roll/week

at 1 roll/week · best option costs €16/yr vs €34/yr for Kleenex — you save €18/year.

💪 Protein powder — cost per gram of protein

Method: cost per gram of actual protein. Bag weight and serving size are irrelevant — what matters is how much protein you get per euro spent. The most expensive-looking option (Brand D) is actually #2 on protein value.
Myprotein Impact
€24.99
1000g
40
21g
€0.0298
per gram of protein
840g total · €0.62/serving
best value
Décathlon Aptonia
€19.99
750g
25
23g
€0.0347
per gram of protein
575g total · €0.80/serving
Bulk Whey Isolate
€49.99
2000g
67
24g
€0.0311
per gram of protein
1608g total · €0.75/serving
Optimum Gold Standard
€54.99
2270g
73
24g
€0.0314
per gram of protein
1752g total · €0.75/serving

ranking — cost per gram of protein

  • 1.
    Myprotein Impact €0.0298/g best value
  • 2.
    Bulk Whey Isolate €0.0311/g +4%
  • 3.
    Optimum Gold Standard €0.0314/g +5%
  • 4.
    Décathlon Aptonia €0.0347/g +16%

choosing Myprotein Impact over Décathlon saves you 16% per gram of protein.

lifetime cost projection — 5 servings/week

at 5 servings/week · best option costs €163/yr vs €208/yr for Décathlon — you save €45/year.

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