Estimate the monthly cost and payback of an automation, counting your own time.
Add up everything an automation costs you each month, including your own time, and compare that with the time and error cost it saves. If the saving is bigger, the flow pays for itself. Divide the build cost by the monthly gap to find how many months the build takes to repay.
The full monthly cost has five parts:
the tool plan usage charges AI charges any other subscriptions the flow needs the value of the time you spend keeping the flow running
When asked what an automation costs, most people give the tool's monthly plan and stop there, because that is the figure on their credit card statement. The plan price misses the AI charges, which arrive on a separate bill. It also misses the hours spent on the build and the time you spend each month checking and fixing the flow. If you leave all of that out, almost any automation will look like a bargain.
Work out a monthly figure for each of these four costs, for the one flow you are costing.
The tool plan is your subscription to Zapier, Make or n8n. When one plan covers several flows, count only this flow's share. If you run n8n yourself, there is no plan price. Use the cost of the rented server plus the time you spend keeping it updated.
For usage charges, remember that each tool measures usage in its own unit, as lesson 3.1, "Zapier, Make and n8n: three ways to build the same flow", showed. If your plan comes with an allowance, this flow uses up part of it. Once you go past the allowance, you either pay extra or move to a bigger plan.
AI charges apply every time the flow runs an AI step. You pay them through the tool's usage or, if you use your own API key, on the model provider's bill. The amount depends on how much text each run sends out and gets back. Find the figure on the provider's current pricing page and in your usage dashboard rather than guessing it.
Other subscriptions are services the flow needs that you would not pay for otherwise, such as a form tool, a document generation service or a paid messaging app.
Your own hours count twice: once for building the flow, and again every month for keeping it working.
Build time is a one-off cost. Add up the hours you spent designing, building and testing the flow. Count from the flow diagram you drew in module 2 to the failure tests in lesson 7.4, "Break your own flow on purpose".
Maintenance is a monthly cost and is never zero. Connections expire, someone renames a folder, the prompt in the AI step needs adjusting, and items in the review queue need clearing. Set aside a realistic number of hours each month to read the weekly summary from lesson 7.2 and fix whatever it shows. For a small flow, one hour a month is a modest first guess. After a few months, the log from lesson 7.3, "Logs and human review checkpoints", will show how much time upkeep really takes, and you can adjust the allowance to match.
To compare hours with the plan and AI bills, give your time an hourly value. You can work it out in one of two ways. Either divide your salary by your working hours, or use what you would pay someone else to do the task. Choose one and use it for both the costs and the savings, so both sides are measured the same way. Then multiply your build hours and your monthly maintenance hours by that rate.
The savings side starts from your scoring sheet in lesson 1.4, "Score your own task list". It records the task's manual minutes each month and its estimated error cost. Some of the work still needs a person after you automate it, such as reviewing drafts or clearing the review list. Subtract that time from the manual time to get the time saved, then multiply it by your hourly value.
Subtract your monthly costs, including maintenance, from the value of the time saved. The result is your net monthly saving. Divide the build cost by the net monthly saving to get the payback period in months.
Mei Ling handles enquiries at the centre, an education centre that enrols students, and she built a flow to help with them (an invented example; her figures are not real prices or rates). About 15 enquiries arrive each week, which is roughly 65 a month. The process fix in lesson 1.2 had already cut each enquiry to about 3 minutes by hand. With the flow, she spends about half a minute checking each draft, which saves her 2.5 minutes per enquiry. Over a month that is 2.5 minutes x 65 enquiries = 162.5 minutes, or about 2.7 hours. At S$25 an hour, that time is worth about S$67.70 a month.
On the cost side, she pays S$30 a month for the plan. The AI step costs S$0.02 per run, so 65 runs add S$1.30. She allows 1 hour a month for maintenance, which is worth S$25. Her monthly total is S$56.30 (S$30 + S$1.30 + S$25). That leaves her a net saving in time of about S$11.40 a month (S$67.70 - S$56.30).
The build took her about 8 hours, which at S$25 an hour is S$200. Payback is S$200 / S$11.40, about 17 or 18 months. Judged on time savings alone, that is a weak case.
Saving time was never her main reason for building the flow, though. In lesson 1.1 she identified the error cost. In busy months, replies went out slowly and the centre lost students as a result. If the flow prevents even a few lost enrolments a year, that would be worth more than the time figures.
A flow with weak time savings can still be worth building if it prevents a costly error. Write the error cost next to your figures, either as a dollar amount or in plain words, and base your decision on both the time and the error cost.
If the tool or the model provider charges by usage, your costs go up as your volume goes up. Your benefits usually go up too, but not always at the same rate.
Suppose Mei Ling's enquiries doubled to 130 a month. Her time saved would be worth about S$135.40 and her costs would be about S$57.60, so the flow would pay much better. That assumes her plan's allowance still covered the extra runs. An allowance can run out suddenly, and if the extra volume forced her onto a larger plan, the result could swing the other way. Do the sums again whenever your volume doubles or a tool changes its pricing.
In the activity below, you will fill in a cost sheet for your main flow with the plan, usage, AI and maintenance costs, and calculate the monthly payback. Use real figures from your accounts and pricing pages where you have them, and label every estimate as an estimate.
Fill in a cost sheet for your main flow with plan, usage, AI and maintenance costs, then work out the monthly payback.
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