8 Numbers That Every LEGO Reseller Should Know

Category: Investing

By BrickBucks

Eight numbers that distinguish a real LEGO reselling business from a hobby that loses money. Track them or lose money.

Casual LEGO resellers track revenue. Serious ones track unit economics. The difference between a hobby that costs money and a real side income usually comes down to whether you measure the right numbers. Here are the eight metrics every LEGO reseller should be tracking — and what target values look like.

1. Gross margin per set

Definition: (Sale price − cost of goods − platform fees − shipping) / sale price.

Target: 40-60% on retired sets. 15-30% on near-MSRP in-production sets. Below 15% means you're working for free.

Why it matters: revenue without margin is just movement. A $200 set sold for $250 with $40 in fees and $20 in shipping nets $190 from a $200 cost — a loss disguised as a sale.

2. Sell-through rate (90 days)

Definition: percent of inventory sold within 90 days of listing.

Target: 60%+ on sealed retired sets, 80%+ on common parts.

Why it matters: low sell-through is a price problem or a sourcing problem. If your sealed sets aren't moving in 90 days, you're priced above market or the items aren't in demand.

3. Cost per part (Bricklink stores)

Definition: total cost of parted-out sets / total number of saleable parts produced.

Target: $0.04-$0.08 average per common part, lower on bulk parted-out sets.

Why it matters: the Bricklink resell math only works if your parts cost ~25-35% of the average sale price per part. If cost-per-part drifts above $0.10, you're competing on premium items only.

4. Return on investment (ROI) per set

Definition: (Net proceeds − cost basis) / cost basis. Expressed as annualized return if hold period exceeds 1 year.

Target: 50%+ total return on retired-set sales held 2+ years. 12-20% annualized after fees.

Why it matters: raw dollar profit without ROI context is misleading. A $200 profit on $1,000 invested over 3 years is a much better outcome than $200 on $5,000 invested over 5 years.

5. Average hold period

Definition: average days between purchase and sale of an inventory item.

Target: dependent on strategy. Flipping near-MSRP sets: under 90 days. Investment sets: 3-7 years. Bricklink parts inventory: 30-180 days per SKU.

Why it matters: hold period is the denominator on annualized returns. A 60% gain over 6 months is much better than a 60% gain over 6 years — but the latter is what casual resellers settle for.

6. All-in fee load

Definition: (platform fees + payment processing + shipping costs) / gross sale price.

Target: Bricklink ~8-12%. eBay ~16-22%. Amazon ~25-32%. Facebook Marketplace local ~0-3%.

Why it matters: sellers consistently underestimate fee load and overestimate net margin. Track it explicitly.

7. Return rate

Definition: percent of completed sales that result in returns or refunds.

Target: under 3% on sealed sets, under 5% on parts and used items, under 8% on bulk lots.

Why it matters: high return rate signals listing accuracy problems, shipping damage problems, or buyer-mismatch problems. Each return costs you 100% of the sale plus return shipping plus restocking time.

8. Inventory turn (annual)

Definition: total annual revenue / average inventory value at cost.

Target: 2-4× for flip-focused resellers. 0.3-0.5× for hold-focused investors. Below 0.2× on flip inventory means you have a stale-inventory problem.

Why it matters: inventory tied up in slow-moving stock is dead capital. A turn rate below your target is a signal to liquidate stale items at a small loss and rotate capital into faster-moving inventory.

The reseller scorecard template

A monthly spreadsheet that tracks these eight numbers across your active inventory takes ~30 minutes to maintain and saves multiples of that in bad-decision avoidance. For a starting template structure:

For broader strategy, see our ultimate LEGO investing guide and 9 Bricklink selling tips.