Buy 1 Get 1 vs 40% Off — Which Is Actually Better?
Ever stood in a supermarket aisle choosing between a BOGO deal on one brand and 40% off on another? Most people grab the 40% off because the number looks bigger — but Buy 1 Get 1 = 50% off, which is almost always better. Here's the math so you never have to guess again.
This article breaks down every common promo type with real calculations — so you can make the right call in seconds, every time.
The Math Behind "Buy 1 Get 1" (BOGO)
Let's work through a real example step by step:
- Shampoo, standard price: $5.00 per bottle
- Buy 2 at regular price = $10.00
- With Buy 1 Get 1 = pay $5.00, get 2 bottles
Discount = ($5.00 − $2.50) ÷ $5.00 × 100 = 50%
So Buy 1 Get 1 always equals 50% off — for the same product at the same price.
"Buy 2 Get 1" Works the Same Way
Pay for 2, receive 3:
- Yoghurt cups, $2.00 each
- Buy 2 = pay $4.00, get 3 cups
Discount = ($2.00 − $1.33) ÷ $2.00 × 100 = ~33%
Buy 2 Get 1 always equals a 33% discount — for the same product.
Quick-Reference Table: Every Promo Type
Save this table for your next grocery run:
| Promotion | Equivalent Discount | You pay per item |
|---|---|---|
| Buy 1 Get 1 (BOGO) | 50% | 50% of original |
| Buy 2 Get 1 | 33% | 67% |
| Buy 3 Get 1 | 25% | 75% |
| Buy 4 Get 1 | 20% | 80% |
| Buy 5 Get 1 | ~17% | 83% |
| 10% off | 10% | 90% |
| 30% off | 30% | 70% |
| 50% off | 50% | = BOGO |
When Does "40% Off" Actually Beat BOGO?
Short answer: when they're different brands or sizes.
Real-world example — comparing across brands:
- Brand A: 600ml bottle, $4.00 + Buy 1 Get 1
- Brand B: 1.5L bottle (1,500ml), $6.00 + 40% off
BOGO → $2.00 per bottle → $2.00 ÷ 600ml = $0.0033/ml
Brand B:
40% off → $6.00 × 0.6 = $3.60 → $3.60 ÷ 1,500ml = $0.0024/ml
In this case, Brand B (40% off) wins — even though the promo looks worse, the larger size makes it cheaper per ml.
3 Traps People Fall Into Every Week
- Assuming BOGO = 33% — it's 50%, every time, for the same item.
- Thinking "Buy 2 Get 1" means half price — it's 33%, not 50%.
- Assuming bigger pack = cheaper per unit — in 30–40% of cases it isn't. Always check.
Don't want to do the math in your head?
Enter price + quantity + promo type into DealCheck — it calculates the unit price instantly.
🔍 Compare prices nowSummary (memorise these)
- ✅ Buy 1 Get 1 = 50% off, always
- ✅ Buy 2 Get 1 = 33% off, always
- ✅ % off = exactly what it says
- ⚠️ Different brands / sizes = must compare unit price (per ml, g, or piece)
- 💡 Use DealCheck when you can't decide in-store
Next time you're standing in the aisle — take 30 seconds to compare unit prices. It adds up to hundreds of dollars a year.