May 13, 2026 · 7 min read
ROAS Calculator: Formula, Examples & Free Tool for Agencies
Learn the ROAS formula, see worked examples, and use a free ROAS calculator to forecast return on ad spend for any campaign.
Return on ad spend (ROAS) is the single most-asked metric in performance marketing — and the one most often miscalculated. A ROAS calculator turns the math from a back-of-envelope guess into a forecast you can defend to a client or a CFO. This guide walks through the formula, three worked examples, and how to use ROAS as a decision tool rather than a vanity number.
The ROAS formula
ROAS = Revenue from ads ÷ Ad spend. A ROAS of 4.0 (often written as 4:1 or 400%) means every $1 of ad spend returned $4 in tracked revenue. The formula is deliberately simple, which is why it's also easy to misuse.
Three worked examples
1. E-commerce campaign
Spend: $20,000. Tracked revenue: $90,000. ROAS = 4.5. On its own, that looks great — until you account for COGS at 55%, fulfilment at 8%, and the platform's 2.5% take rate. The real margin contribution drops to roughly $6,800. See our break-even ROAS guide for how to back into the threshold.
2. Lead-gen agency
Spend: $45,000. Closed revenue (90-day attribution): $180,000. ROAS = 4.0. But leads-to-revenue takes a quarter, so reporting ROAS without a window is misleading. Pair it with customer acquisition cost and a payback period.
3. SaaS subscription
Spend: $12,000. First-month subscription revenue: $4,800. ROAS = 0.4 — looks like a disaster, but if average lifetime value is $2,400, the campaign is profitable inside 90 days. SaaS teams should track LTV-based ROAS and LTV:CAC ratio instead.
What "good" ROAS looks like
- E-commerce with 60% gross margin: ~3.0–4.0 ROAS to be profitable
- High-margin info products: 1.5–2.0 can be plenty
- Subscription with long payback: first-month ROAS < 1.0 is fine if LTV holds
Google's own teams publish good baselines on Think with Google, and Stripe's merchant guides are a solid reference for how transaction fees affect the calculation.
Use a calculator that respects your margins
A standalone ROAS calculator is useful, but it ignores fixed opex, closing rate, and gross margin — the levers that actually decide whether a campaign scales. ProfitPulse models all of them in real time so you see the scaling-velocity impact alongside the headline ROAS.