How We Score Durability: The Last Buy Index Explained

Most product review sites tell you what's popular. We tell you what lasts.

Every product on The Last Buy gets a Durability Index — a score from 0 to 10 that represents how long we expect it to hold up under real-world use. Not lab conditions. Not marketing claims. Real ownership, over years and decades.

Here's exactly how we calculate it, factor by factor.

The Five Factors

Our Durability Index weighs five factors. Each factor is scored independently on a 0-10 scale, then combined into the final composite score. No black boxes. No mystery algorithms. Just five things that actually predict whether a product will last.

1. Warranty (Weight: High)

A warranty is a manufacturer's bet on their own product. We score it based on coverage length, what's included, and how easy it is to actually use.

10/10: Lifetime, unconditional warranty. The company will replace or repair the product, no questions asked. (Example: Lodge cast iron — lifetime warranty, scores 10.)
7/10: Multi-year limited warranty with reasonable terms.
3.5/10: Standard 1-year manufacturer warranty with restrictive conditions.

Why it matters: Companies don't offer lifetime warranties on products they expect to fail. When Victorinox warranties their Swiss Army Knife for life, or Darn Tough guarantees their socks unconditionally, they're telling you something their marketing won't: they built it to not come back.

2. Materials (Weight: High)

What is the product actually made of? We evaluate material quality, construction method, and how the materials age under normal use.

9.5/10: Premium, proven materials. Full-grain leather, cast iron, marine-grade stainless steel, solid hardwood. (Example: Lodge Cast Iron Skillet — 9.5.)
7-8/10: Good materials with some compromises. Tempered glass, quality synthetics, mid-grade metals.
4-6/10: Materials that degrade predictably. Bonded leather, thin-gauge plastic, coated surfaces that wear.

Why it matters: Materials are the single best predictor of physical lifespan. A cast iron skillet doesn't care how many times you use it — the material doesn't degrade with use. A nonstick coating does. That difference shows up in decades of ownership.

3. Community Sentiment (Weight: Medium-High)

We aggregate real ownership feedback from communities like r/BuyItForLife, r/Frugal, and product-specific forums. We're looking for long-term satisfaction — not day-one unboxing excitement.

9.5+/10: Overwhelmingly positive multi-year feedback. Products people actively evangelize. (Example: Vitamix Blender — 9.6 sentiment.)
8-9/10: Broadly positive with minor, consistent complaints.
Below 7/10: Mixed reviews, common failure reports, or declining quality over production years.

Why it matters: Aggregate ownership experience across years is the closest thing to a real-world durability test. When hundreds of people independently report that their KitchenAid mixer still runs after 15 years, that's data — not anecdote. We weight sentiment from long-term owners more heavily than recent purchasers.

4. Brand Reputation (Weight: Medium)

We evaluate the brand's track record for durability specifically — not marketing presence, not market share. Has this company consistently produced products that last?

9.5+/10: Decades-long reputation for durability. The brand name is synonymous with lasting quality. (Example: Lodge — 9.8, Le Creuset — 9.8, Snap-on — 9.8.)
8-9/10: Strong durability reputation with broad community trust.
Below 7/10: Mixed track record, known quality declines, or inconsistent across product lines.

Why it matters: Brands with strong durability reputations have something to protect. They're less likely to cut corners on materials or manufacturing because their entire value proposition depends on longevity. A brand scoring 9+ has earned that score across many products and many years.

5. Repairability (Weight: Medium)

Can you fix it when something goes wrong? We evaluate parts availability, design accessibility, and whether the product was built to be maintained or discarded.

8+/10: User-serviceable with readily available parts. Designed for repair. (Example: Dualit Toaster — 8.7. You can replace heating elements yourself.)
6-7/10: Repairable by professionals, parts available but not trivially accessible.
3-4/10: Sealed, glued, or designed in a way that makes repair impractical or uneconomical.

Why it matters: Even the best products eventually need maintenance. A KitchenAid mixer (repairability: 8.0) with a worn gear can be fixed for $20 in parts and keep running for another decade. A sealed appliance with the same problem goes in the trash. Repairability doesn't just extend lifespan — it's what makes "buy it for life" actually possible.

How the Scores Combine

The five factor scores combine into the final Durability Index using a weighted formula. Warranty and materials carry the most weight because they're the most predictive of actual product lifespan. Community sentiment carries significant weight because it represents real-world validation. Brand reputation and repairability round out the picture.

A product needs strong scores across multiple factors to earn a high Durability Index. A great warranty on a poorly-made product won't score well. Excellent materials with zero repairability will be limited. The system rewards products that are durable by design — built well, backed confidently, validated by owners, and maintainable over time.

Confidence Levels

Not every product has equal data available. We assign a confidence level to each score:

High confidence: All five factors scored with strong data sources. These are our most reliable ratings.
Low confidence: One or more factors scored with limited data. The rating is directional but less precise.

We'd rather be transparent about uncertainty than pretend every score is equally solid.

What the Scores Mean in Practice

| Score Range | What It Means | |---|---| | 9.0 - 10.0 | Exceptional. Multi-generational durability. The gold standard of BIFL. | | 8.0 - 8.9 | Excellent. Built to last decades with proper care. | | 7.0 - 7.9 | Good. Significantly outlasts average products in its category. | | 6.0 - 6.9 | Above average. Durable for its class but not truly BIFL. | | Below 6.0 | Average or below. Expect a normal product lifespan. |

Why Transparency Matters

We built the Durability Index because we were frustrated with review sites that tell you what to buy without telling you why — or worse, tell you what to buy because someone paid them to.

Every score on The Last Buy can be traced back to its five components. You can see exactly why a product scored the way it did. Disagree with our assessment? The breakdown is right there. You have the same data we do.

Our goal isn't to be the final word on durability. It's to give you a structured, honest framework for making purchases that don't end up in a landfill two years from now.

That's the whole idea. Fewer purchases, better ones, and a lot less waste.