An AI ROI calculator for a small business needs four numbers: the hours one job takes today, the true cost of an hour worked, an honest saving after checking time and non-users, and every cost including set-up. Divide the yearly net saving by the yearly cost. If the honest figure pays back within six months, trial it. If only the vendor’s figure does, stop.
Why do most AI ROI calculators give the wrong answer?
Most AI ROI calculators give the wrong answer because they multiply a vendor’s best-case saving by everyone’s salary.
They assume every person uses the tool, every output is right first time, and every saved minute turns into money. None of those three holds in a real 12-person firm.
The formula itself is fine. Return on investment is the net benefit divided by the cost. The trouble is the inputs. A calculator that asks “how many staff do you have?” before “which job are you fixing?” has already gone wrong.
Bedrock AI’s view is that an hour saved is worth nothing until you can name what fills it. If the saved time becomes more quotes sent, fewer late nights or a hire you no longer need, it is money.
If it disappears into the week, it is a nice feeling.
How much time does AI actually save at work?
Two large studies put the average saving at a little over two hours a week per person who actually uses AI. The St. Louis Fed’s November 2024 survey found users saved 5.4% of their work hours, about 2.2 hours in a 40-hour week.
The UK government’s own trial landed in the same place. The cross-government Microsoft 365 Copilot experiment gave about 20,000 government employees licences from September to December 2024. Users reported saving 26 minutes a day on average, which is roughly 2.2 hours over a five-day week.
The spread matters more than the average. In the Fed survey, 33% of users saved an hour a week or less, while 20.5% saved four hours or more. In the government trial, 17% noticed no clear time saving at all.
Both studies rely on people estimating their own time, and the government report says so plainly. Treat two hours a week per active user as a ceiling for general office work, then test it against your own job.
How do you calculate AI ROI for a small business?
You calculate AI ROI for a small business in six steps, and the order matters. Each step narrows a hopeful number into one you can defend.
- Pick one job. Name a single task, such as writing quotes or answering the same five customer emails. “Using AI in the office” cannot be measured.
- Time it for a week. Ask the people who do the job to log how long it takes. Guesses run high or low, and both ruin the sum.
- Cost an hour worked. Add employer National Insurance to pay, then divide by the hours people actually work, after holidays.
- Discount the saving. Subtract the time spent checking AI output, and leave out anyone who will not use it.
- Count every cost. Include seats, set-up hours and training hours, valued at the same hourly rate.
- Apply the payback rule. Divide one-off costs by the monthly net saving to get payback in months.
Step one is where most of the value sits. Our guide to scoring your workflows shows how to pick the job with the most volume and the highest cost of delay.
What is an hour of staff time really worth?
An hour of staff time is worth more than the hourly wage, because National Insurance, holidays and bank holidays all sit on top. Use the cost per hour actually worked, or every saving looks smaller than it is.
Take the UK median. The ONS Annual Survey of Hours and Earnings puts median hourly pay for full-time employees at £19.67 in April 2025. Over a 37.5-hour week, that is about £38,357 a year.
Employer National Insurance adds 15% on earnings above £5,000, according to HMRC’s 2026 to 2027 rates. On this salary that is about £5,003, for a total of £43,360. Pension contributions come on top, and this example leaves them out to stay conservative.
Full-time staff are entitled to 5.6 weeks of paid holiday under GOV.UK’s holiday rules. That leaves about 46 working weeks, or 1,725 hours. So £43,360 divided by 1,725 hours gives £25.14 per hour worked, against a headline wage of £19.67.
What does a worked AI ROI example look like?
A worked AI ROI example for a 12-person firm shows the honest saving at well under half the vendor’s figure, and still worth doing. Here, four office staff each spend six hours a week writing quotes and client emails.
The vendor says AI halves the job. The honest version assumes 1.5 hours saved per person after checking each draft. It also assumes one of the four never really takes to it, which is close to the 17% who saved nothing in the government trial.
| Input | Vendor-style calculator | Honest calculator |
|---|---|---|
| Hours on the job per week | 24 (4 staff × 6) | 24 (4 staff × 6) |
| Hours saved per week | 12 (half the job) | 4.5 (3 users × 1.5) |
| Working weeks a year | 52 | 46 |
| Cost of an hour | £19.67 (wage only) | £25.14 (loaded, per hour worked) |
| Yearly saving | £12,274 | £5,204 |
| ChatGPT Business seats | Often left out | £720 (4 × £15 × 12) |
| Set-up and training | Left out | £578 (23 hours × £25.14) |
| First-year net return | £12,274 | £3,906 |
The seat price comes from OpenAI’s pricing page. As of October 2026, a standard ChatGPT Business seat is £15 per user per month on annual billing. The 23 hours cover 15 hours of set-up and two hours of training for each of the four staff.
On the honest numbers, first-year costs are £1,298 against a £5,204 saving. That is a return of about 300% in year one.
The monthly saving is £434, less £60 in seats, leaving £374 a month. The £578 of one-off costs pays back in under two months.
The vendor figure is more than twice as high, and it is the one that gets quoted in sales calls. The honest figure is the one you can hold a supplier to.
When is an AI project not worth the money?
An AI project is not worth the money when the job is too small to repay the set-up. The same goes when the saving only works on the vendor’s assumptions. Three signs show up before you spend anything.
The first is a small job. If the task takes the whole team two hours a week, halving it saves 46 hours a year. At £25.14 an hour that is £1,156, and two seats plus 20 hours of set-up take £863 of it.
The second is a saving with nowhere to go. If nobody can say what the freed hours will be used for, the return stays on paper. The government trial itself could not establish how saved time was spent.
The third is a tool nobody opens after week three. Adoption is the input most calculators skip, and it is the one that most often turns a good sum into a loss. Our piece on why AI tools get abandoned covers the usual causes.
Bedrock AI’s rule is to trial anything that pays back within six months on the honest numbers. If it only pays back on the vendor’s numbers, it does not get built.
How do you check the ROI once AI is in use?
You check the ROI once AI is in use by timing the same job again after four weeks. Use the same people and the same log. Compare the new weekly hours with the baseline, then rerun the sum with the measured figure.
Four weeks is long enough for the novelty to wear off and short enough to cancel a monthly plan.
If the measured saving is below half your honest estimate, find out why before adding seats. Often one person has found a better way to use it, and the others need showing.
Before you add seats, check the account settings too. Our guide to whether ChatGPT is safe for business use covers which plan keeps client data out of training. If the build-or-buy question comes up next, see build vs buy AI for a small business.
FAQ
What is a good ROI for AI in a small business? A good ROI for AI in a small business is one that pays back its set-up costs within six months on measured hours. In the worked example above, a 12-person firm paid back in under two months and returned about 300% in year one.
Can I use a free AI ROI calculator online? A free AI ROI calculator online is fine for the arithmetic, but check its assumptions first. Most use the wage instead of the loaded hourly cost, assume every member of staff uses the tool, and leave out set-up and training time.
How many hours a week does AI save per employee? AI saves about 2.2 hours a week per active user on average, according to both the St. Louis Fed survey and the UK government Copilot trial. The spread is wide, and 17% of government trial users noticed no clear saving.
Should I count the owner’s time in an AI ROI calculation? The owner’s time should count in an AI ROI calculation, usually at a higher rate than staff time. Set-up often falls on the owner, so valuing those hours at zero makes the project look cheaper than it is.
Can an AI ROI calculation include extra sales as well as time saved? An AI ROI calculation can include extra sales, such as enquiries answered out of hours that would otherwise be lost. Count them only once you have measured them for a month. Projected sales are the easiest number in the sum to inflate.
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