Agency ROI calculator

• Total monthly cost = your monthly fee + the client's other monthly costs (ad spend, software).
• Monthly revenue gain = client's current monthly revenue x projected increase %.
• Monthly ROI = (monthly gain - monthly cost) / monthly cost, once results have started.
• 12-month ROI counts 12 months of cost but only the months after the implementation period as gain.
• Break-even (payback) month is the first month in which cumulative gain reaches cumulative cost. Solved directly: month = implementation months x monthly gain / (monthly gain - monthly cost), rounded up. If the monthly gain never exceeds the monthly cost, the engagement never pays back.
• Months of results needed = break-even month - implementation months.

Worked example

With the defaults, the client pays a $5,000 fee plus $1,000 of other costs: $6,000 a month. Their $50,000 monthly revenue rises 20%, a $10,000 monthly gain, after a 3-month implementation period. Once results start, monthly ROI is ($10,000 - $6,000) / $6,000 = 66.7%. Over 12 months the client pays $72,000 and gains $90,000 (9 months x $10,000), a $18,000 net gain and 25% ROI. Cumulative gain first passes cumulative cost in month 8 ($50,000 gained against $48,000 spent).

How to read the result

The calculator uses revenue gain, not profit. A client with a 30% margin keeps only $3,000 of a $10,000 revenue gain, which would not cover a $6,000 monthly cost. For a profit-based view, enter the projected increase multiplied by the client's margin. In the example, 20% x 30% = 6%.

Payback and break-even are the same month in this calculator. In the example, month 8 is 3 x $10,000 / ($10,000 - $6,000) = 7.5, rounded up; that is 5 months of results after the 3-month implementation period. A longer ramp-up pushes it out quickly: with a 6-month implementation period the same numbers break even in month 15.

Services differ in how quickly results show up and how easy they are to attribute. Set the implementation period to match:

• PPC and paid media: usually the quickest to measure, because spend and conversions are tracked in the ad platforms.
• SEO and content: slower to start and build over time, so a 12-month view can understate them.
• Web design and development: a one-off cost with returns through conversion rate; the gain depends on traffic.
• Branding: hardest to attribute directly; returns show up in pricing power and lower acquisition cost.
• Social media: paid social is easier to measure than organic, which is often an awareness play.

Use the client's own historical results or your past results for similar clients to set the projected increase and implementation period, not a generic figure.

• Start with the client's numbers. Ask for monthly revenue, traffic or lead volume before you propose.
• Show three scenarios. Conservative, expected and optimistic, so the client sees the range.
• Show the break-even month. Clients want to know when the spend is covered.
• State the ramp-up. Be explicit about how long before results start.

Common ROI calculation mistakes

• No implementation period: gains rarely start in month one.
• Revenue treated as profit: the client keeps only their margin on new revenue.
• Missing costs: ad spend, software and content reduce net ROI.
• Weak attribution: separate your results from seasonality and other campaigns.
• Measuring too early: slow-build services will look negative in the first months.