How our scores work

R(m) = median Good-condition used price at age m ÷ launch price

We measure R at 6, 12, 24 months, using Good-condition prices from when the product was within 1 month of that age (at least 3 prices). A product too young to have a checkpoint gets an estimate from its product family's average curve (or its category's), and we mark it est.

Sneakers, shoes, clothing, bags and accessories often sell unchanged for years, so for them we use the current US retail price in place of a launch price, and age is counted from when that version went on sale. Used prices pool all sizes.

Retention score = 100 × (0.2 × R(6) + 0.3 × R(12) + 0.5 × R(24))

Scores of 70+ are Strong, 45–69 Fair, below 45 Weak.

Real buy-in = (Price paid − Expected Good-condition resale at month m) ÷ m

By default the price paid is today's price and m is 24 months. Expected resale is the launch price × R(m), read from the retention curve (straight lines between the checkpoints), but never more than today's median Good-condition resale price: a device you buy today can't be expected to resell later for more than it already sells for used. The calculator on each product page lets you change both, from 1 to 24 months.

WorthBuyIn Score = 0.6 × Retention score + 0.4 × (100 − cost percentile)

The cost percentile ranks the product's real buy-in among similar devices (laptops, phones, tablets, watches, earbuds): 0 is the cheapest to own, 100 the most expensive. Macs are compared with Windows laptops and iPhones with Android phones. We always show the score with its two ingredients.

Not enough data: with fewer than 10 Good-condition used prices, or under 3 months on sale, we show “Not enough data yet” (or “Too new to score” for new models) instead of inventing a number.

Exactly three states, decided in this order:

• Wait if a new model in the same family is expected within 60 days, or a sale that usually cuts 10% or more starts within 21 days and today's price is above the 25th percentile of the last 180 days.
• Buy now if today's price is at or below the 20th percentile of the last 180 days and no new model is expected.
• Fair otherwise.

Every signal comes with a one-sentence reason built from the same inputs, so the banner, the signal, the takeaways and the price chart always agree.

Today's price is the lowest current new price across our sources (a source's price counts for up to 14 days). It's Good at or below the 25th percentile of the last 180 days, High above the 75th, and Fair in between. The usual range is the 25th to 75th percentile.

For each condition (Excellent, Good, Fair) we show the 25th to 75th percentile of used prices from the last 30 days, when there are at least 3. Until we have sold-price data these are asking prices, labeled “based on current listings”.

Prices outside 30%–150% of the typical price for that product and condition around the same time are treated as mistakes and left out.

The chart shows the lowest new price each day. Shaded areas mark sale events; upcoming sales and expected new models are listed above the chart.

Brand Value Score = 50% average retention score + 30% discount behavior + 20% off-price presence

Discount behavior is higher when a brand's products spend fewer days on sale, at smaller discounts, over the last 365 days. Off-price presence is a neutral 50 until we have outlet and off-price data.

We only use sources whose terms allow it, prefer official APIs, store facts only (product, price, condition, date, source link), and never show third-party listing photos or descriptions.

Sources in use right now: eBay Browse API, Manual entry (admin), Seed CSVs.

Prices people report on the site are checked by our team before they count.

Brands and retailers can't pay for placement or to change any score. If we ever use affiliate links, we'll say so right next to the link. Worth Buy In is not affiliated with Apple or any other brand shown.

Formula version 1.2.0. Retention is measured up to 24 months. About us