The reverse rate calculator nobody's built.

You get an offer for $35/hour. Is that good? Bad? Robbery? Every calculator on the internet asks what rate you want — none tell you what the rate you were offered actually means.

The pain is documented.

Search r/freelance for "is X/hr good" and you'll find the same question asked roughly twice a week, every week, for the last six years.1 The answers are anecdotal. The data exists — it just isn't packaged for the moment a contractor needs it: thirty seconds before responding to a client email.2

Existing calculators (Clockify,4 Bonsai,5 half a dozen Notion templates) all run forward: input your salary expectation, output a rate. Useful when you're setting your rate. Useless when someone has already proposed one.

The evidence of demand.

Three numbers that matter:

The distribution of senior React contractor rates in North America (n=312) shows a median of $92/hr, with the long left tail where most lowball offers land.6

The proposed product.

A single-page tool. You paste a rate, your stack, your region, your seniority. It returns where that number sits in the live distribution: percentile, comparable roles, and one honest sentence — "this is a 31st-percentile offer for your stack; here's a counter that lands at the 60th."

Competitive landscape:

The build flow.

Four steps, all static:

1. Scrape boards — Upwork, Toptal, public LinkedIn, Indie Hackers. Weekly.
2. Normalize — stack tags, regions, seniority levels. Drop noise.
3. Bin + percentile — by stack × region × seniority cell.
4. Serve as JSON — static, CDN-cached. No backend.

Reasons this might not work.

The full risk register is below the fold. The short version: rate data goes stale fast, anchoring cuts both ways, and nobody pays for a calculator. Each has a mitigation. None is a dealbreaker.78