I put the same small business through two free AI ROI calculators and got two answers that cannot be compared. One said AI would grow revenue. The other said AI would cut costs. Both were right about their half of the story, and neither told me about the other half.
The two tools are Vendasta's AI Employee ROI Impact Calculator and UD's own AI Savings Calculator. If you are deciding whether an AI employee is worth paying for, the choice of calculator quietly decides which question you end up answering. This page compares them on the same criteria, shows where each one wins, and gives you a prompt that combines both halves into a number you can defend.
What does each AI ROI calculator actually measure?
Vendasta's calculator measures revenue you are missing: enquiries that arrive after hours or wait too long for a reply, converted into projected annual revenue lift. UD's AI Savings Calculator measures cost you could remove: staff time, efficiency, errors and waste, converted into monthly savings against an AI fee. One is a sales model, the other a cost model.
That difference is not a detail. It decides which businesses each tool flatters:
--- Vendasta's logic, as described in the FAQ on its calculator page: take your monthly lead volume, multiply by the share of leads missed at night and on weekends, then apply a 5 to 10% conversion lift from instant replies. The page cites research that up to 40% of enquiries arrive outside business hours.
--- UD's logic: pick one of eight industries, set headcount, average monthly salary, opening hours and an industry metric (for restaurants, monthly delivery orders and food waste rate), and the tool returns savings split into labour, efficiency, errors and waste, minus a calculated AI monthly fee.
A clinic that loses bookings every evening will look great in Vendasta and modest in UD. A restaurant with heavy admin and food waste will look the other way round.
Vendasta vs UD AI Savings Calculator: the facts side by side
Both calculators are free and run in a browser. Vendasta is a six-step English tool priced in US dollars, built by a company that sells AI employees through agencies. UD's tool is a Chinese-language, eight-industry calculator for Hong Kong businesses, shows results without sign-up, and puts its full report behind a contact form. Both were checked live on 13 October 2026.
Vendasta AI Employee ROI Impact Calculator
--- Price: free.
--- Format: six-step interactive form in English, US dollars.
--- Outputs: after-hours capture value, speed-to-lead lift, projected annual lift, hours saved per year, and current versus "with AI" annual revenue.
--- Report: saved report requires completing a form.
--- Built by: Vendasta, a Canadian platform that sells AI receptionists and other AI employees, mostly through agencies.
--- Related product pricing: Vendasta's own changelog lists Conversations AI at US$29 (Standard), US$39 (Pro) and US$79 per month (Premium, which adds voice with 300 minutes), and a mandatory US$49 per month support fee for the first three months of new AI Receptionist setups from 10 March 2026. These posts are undated in places, so confirm current prices with Vendasta.
UD AI Savings Calculator
--- Price: free, results visible without sign-up.
--- Format: Chinese interface, eight industries (catering, retail, property agency, education, medical clinics, logistics, construction, beauty), sliders for headcount (1 to 100), salary ($10,000 to $40,000) and opening hours (8 to 24).
--- Example output (catering defaults): 5 staff at $18,000, 10 hours a day, 500 delivery orders, 15% waste gives $38,325 monthly savings (labour $23,625, efficiency $7,800, errors $1,500, waste $5,400) against a $7,875 AI fee, a 387% ROI, and $1,379,700 over three years.
--- Report: full report requires name, company and email; there is also a WhatsApp contact button.
--- Built by: UD, the publisher of this page, which sells the AIStaff solution the calculator points to.
Where does Vendasta win, and where does UD win?
Vendasta wins when your real problem is lost sales from slow or after-hours replies, because it is the only one of the two that models revenue. UD wins when your problem is staff cost and workload in a Hong Kong business, because it uses local salary ranges, industry-specific inputs and a Chinese interface. Neither wins on transparency.
Vendasta is the better tool when:
--- you run a business where missed enquiries are the main leak, such as a clinic, salon, tutoring centre or property agency that gets messages at 11pm;
--- you need to justify AI to a sales-minded owner who cares about growth, not headcount;
--- you are comfortable working in US dollars and a US benchmark frame.
UD's calculator is the better tool when:
--- your team is stretched and the question is whether AI can absorb routine work without new hires;
--- your industry is one of the eight covered and you want inputs like delivery orders or waste rate rather than abstract hours;
--- you want a quick Chinese-language estimate in thirty seconds, without filling in a form first.
The honest summary: if you only run one, you only see half the case. A restaurant that adds an AI ordering assistant might save staff time and also capture late-night orders. Neither tool shows both.
What are the honest limitations of both calculators?
Both are lead-generation tools from companies that sell AI, and both hide key assumptions. Vendasta does not show how its six steps turn into the final lift on the page itself. UD does not disclose its formula, shows money only as "$", and projects three years with no ramp-up. Treat every output as a hypothesis, not a quote.
UD AI Savings Calculator, first:
--- Hidden formula. You cannot see or adjust the share of work AI is assumed to absorb, which is the single most sensitive input.
--- Straight-line projection. Year 2 and year 3 are simply year 1 multiplied, with no setup period, learning curve or review time.
--- Calculated AI fee. The $7,875 monthly fee in the example is produced by the tool, not entered by you, so it may not match a real quote.
--- No revenue side. Missed sales and after-hours demand are not modelled at all.
Vendasta:
--- Revenue optimism. The page claims businesses "typically" find annual revenue can rise 30% or more, with no method shown. That is a marketing figure.
--- No cost of the AI itself in the headline. The headline is revenue lift; you still need your own subscription, setup and support costs to get to ROI.
--- US frame. Benchmarks, currency and lead behaviour are North American, and Hong Kong customers on WhatsApp may behave differently.
We could not see every one of Vendasta's six input screens without running the interactive form, so this comparison relies on the page's published outputs and FAQ method. For a wider field, see our comparison of free AI savings calculators, which also covers Layer3 Labs and Cloudswitched.
Which AI ROI calculator should you use?
Use Vendasta if lost enquiries are your biggest leak, UD's calculator if staff cost is, and both if you are not sure. Then combine the two outputs in one stress-test prompt that adds the costs neither tool counts: setup, review time and a slow first quarter. The combined conservative number is the one to take into a budget meeting.
The verdict by user type:
--- Clinic, salon or agency owner losing evening bookings: start with Vendasta's model, then check the cost side in UD's.
--- Restaurant, retail or logistics manager with an overloaded team: start with UD's calculator, then ask whether faster replies would also bring in orders.
--- Practitioner writing the business case for your boss: run both and use the prompt below.
Try this prompt:
I ran two free AI ROI calculators for the same business.
Revenue side (Vendasta): monthly enquiries [number], share arriving after hours [%], projected annual revenue lift US$[amount].
Cost side (UD AI Savings Calculator): [staff] staff at HK$[salary] per month, estimated monthly savings HK$[amount], AI fee HK$[amount].
Act as a cautious finance manager in Hong Kong. Convert everything to HKD at 7.8. Then build conservative, base and optimistic scenarios. For each one:
1. Count only the revenue lift you can tie to a specific channel, such as WhatsApp or web chat.
2. Assume the first three months deliver 25% of the target.
3. Add a one-off setup cost of HK$[your estimate, or "unknown, assume a range"] and 3 hours a week of staff review time at our hourly rate.
4. Show monthly net benefit, first-year net benefit and payback month.
Present it as a table, then tell me which single assumption moves the result most and what evidence I should collect to pin it down.
If the conservative scenario still pays back within a year, the project is worth a proper quote. For what real AI staff costs look like locally, see our Hong Kong AI staff pricing guide.
A calculator is where the conversation starts, not where it ends. Pick the one that matches your real problem, add the half it ignores, and you walk into the meeting with a number that survives the first hard question. We understand AI. We understand you better. With UD by your side, AI doesn't feel cold.
Reviewed by the UD AI team. Disclosure: UD operates the AI Savings Calculator compared here. Both tools were checked on their live pages on 13 October 2026; Vendasta pricing comes from Vendasta's public changelog and may have changed. Features and defaults may change.
See your cost-side number in 30 seconds
Pick your industry in UD's free AI Savings Calculator, move the sliders and see monthly, yearly and three-year estimates with no sign-up. When you are ready to turn the estimate into a real plan, we'll walk you through every step, from checking the assumptions to tool setup and deployment.
