Comparable Store Sales (Comps) Formula
How apparel brands calculate comparable-store sales — the same-cohort growth signal that strips out the noise from newly opened doors.
What Comps measures
Comparable store sales — "comps" — is the percentage change in sales for stores or cohorts open for a full comparable period (typically 13+ months). It strips out new-store growth and measures the underlying health of the existing business.
Comps % = (Current Period Sales − Prior Period Same-Store Sales) ÷ Prior × 100For DTC brands without physical stores, comps can be applied to same-cohort customer sales or same-channel sales. The principle is the same: remove expansion-driven growth to see what's happening at the base.
Worked apparel example
Same-store sales: current period $1.08M, prior period $1.0M.
Comps % = ($1.08M − $1.0M) ÷ $1.0M = 8.0%
8% sits in the top band of the illustrative ranges below. The read that matters over time: a year of low-single-digit or negative comps means the existing base is not growing, and fixed store costs spread over flat sales compress margin.
8.0% comps — strong positive growth on same-store base.
Illustrative planning ranges
Illustrative reference points, not a published benchmark — set targets from your own history.
Failure modes we see
New-store growth masking negative comps. A brand reports 15% topline growth — good news. Strip out 20 new stores and same-store comps are −3%. The existing footprint is compressing while expansion dollars paper over the problem.
How RetailNorthstar handles comps
Comps track at chain, cluster, door, and category grain. The "same cohort" definition is enforced cleanly — new doors drop out until their 13th month — so the signal is trustworthy.
Related formulas
- Plan vs Actual Variance — comps vs plan, not just vs LY
- Average Dollar Sales — one of the comps drivers
- Category Mix % — where comps are coming from
See comps by cohort, door, and category — with the drivers (traffic, basket, mix) decomposed.
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