About
Darshita Oza
Performance marketer at an agency. Builds calculators in evenings because the ones online don’t use the math marketers actually need.
I work on roughly forty DTC ecommerce and B2B SaaS accounts a year at a performance marketing agency. My specific focus is ROAS optimization for ecom and attribution work for B2B. I build the calculators on this site (and its companion sites) because the public calculators marketers find by Googling “ROAS calculator” use the wrong math — revenue divided by ad spend, ignoring margin, returns, and processing fees. That’s not ROAS in any meaningful sense.
What I work on
The day job is paid-media optimization for clients spending $20K to $300K per month. About 60% of my book is DTC ecommerce (apparel, beauty, home goods, supplements), 30% is B2B SaaS, 10% is hybrid — companies that started DTC and added a B2B motion. The accounts that taught me the most about contribution-margin ROAS were the ecom ones; the accounts that taught me about attribution were the B2B ones.
For ecom, the day-to-day work is bid management, feed optimization, creative ops, and the slow consolidation of conversion-event taxonomies. The single recurring conversation I have with new clients is some version of: “The number Google Ads is showing you is overstating profitability by 30 to 60 percent. Here’s why, and here’s the math.” That conversation is what the margin-aware ROAS calculator on the homepage of roascalculatorapp.com automates.
For B2B, the work is attribution modeling, multi-touch journey reconstruction, and conversion-value rules in Smart Bidding. The recurring conversation is some version of: “Your last-click ROAS is structurally biased against your top-of-funnel campaigns. Switching to a multi-touch model will reshuffle which campaigns look profitable.” The attribution simulator at myroascalculator.com makes that point visceral.
Why I build calculators
Two reasons. The first is selfish: I needed them. When I was learning paid-media work, I built spreadsheet calculators for myself because the math behind tROAS targets, CPL ceilings, and break-even ROAS wasn’t obvious from the ad-platform UI. I wanted to internalize the math by computing it by hand.
The second is institutional: the calculators on the public web are mostly broken. The first page of Google for “ROAS calculator” returns three or four tools that compute Revenue ÷ Ad Spend and call that ROAS. That’s the number Google Ads already shows. It’s also a number most operators know is misleading. Publishing margin-aware, attribution-aware, funnel-math-aware calculators is a small public-interest contribution.
The calculators are free, no login, no email gate. The benchmark data underneath each calculator is published as an open CSV under CC-BY 4.0. If you want to embed the calculators on your own site, contact me — embed support is on the roadmap.
How I work
Every calculator I publish is one I’ve used at least a hundred times in client work. The formulas are documented openly. The vertical presets come from a combination of my own client base (anonymized) and aggregated industry reports (cited where applicable). Where my own data conflicts with published benchmarks, I report both and note the discrepancy — usually it reflects either selection bias in my client base or measurement-methodology differences in the published source.
The site is updated as the math is refined. The recent example: the True ROAS calculator originally treated payment processing as a flat 3%; in 2025 I added a separate shipping/fulfillment input because client-side data showed that for furniture and home-goods verticals, shipping was the dominant variable cost, not processing. That kind of refinement happens quarterly.
Editorial policy
No vendor money for placement. The agency’s commercial work funds the editorial. Where I have an active commercial relationship with a vendor (currently Groas.ai through agency client engagements), it’s disclosed on the methodology page and in the relevant tool entries.
Find me
- LinkedIn: linkedin.com/in/darshita-oza
- Email: via the contact page
- Calculator embed requests: contact