Market Sizing for Australian Startups

If you're founding or fundraising from Australia, market sizing is the single number that determines whether an investor keeps reading your deck. This guide walks through the standard framework (TAM / SAM / SOM), the two mechanical approaches for calculating each, and, most importantly, how to apply them credibly from an Australian base. It's written for founders at pre-seed through Series A.

The three numbers

TAM — Total Addressable Market. The total revenue opportunity if your product achieved 100% market share, globally, with no competitors. It's a theoretical ceiling. Think of it as: "If every human or business on earth who could possibly use this bought it, at the price they'd pay, what's the annual revenue?"

SAM — Serviceable Addressable Market. The portion of TAM you can realistically reach given your business model, distribution, language, regulation, and geographic focus. This is TAM narrowed by what your company actually does. "Of the global market, which slice can we actually sell into?"

SOM — Serviceable Obtainable Market. The portion of SAM you can realistically capture in a defined time window (usually 3–5 years) given your team, capital, go-to-market, and competition. "Of what we can sell to, what will we actually win?"

The common analogy: TAM is the ocean, SAM is the sea you're sailing in, and SOM is the fish you'll catch this trip. All three should be stated as annual recurring revenue figures — not user counts, not lifetime value, not transaction volume.

The two ways to calculate: top-down vs bottom-up

Top-down

Start with a published industry figure and narrow it down using percentages.

Example: "The global project management software market is US$7.2B (Gartner). Australia represents ~2% of global IT spend, so AU TAM ≈ A$220M. We target mid-market, which is 30% of that = A$66M SAM. We'll win 5% in 3 years = A$3.3M SOM."

Top-down is fast and uses credible-looking sources. The problem: it's almost always wrong, because the report's definition of "the market" rarely matches your product. Investors know this and discount the number heavily.

Bottom-up

Start with unit economics — who your customer is, how many exist, what they'll pay — and multiply up.

Example: "There are 68,000 Australian medium businesses (ABS, 20–199 employees). Our product is sold per seat at A$40/user/month. Average mid-market team size is 15 knowledge workers. 68,000 × 15 × A$40 × 12 = A$489M SAM."

Bottom-up forces you to know your customer and your price. Investors trust it far more. For Australian startups, always lead with a bottom-up approach and use a top-down approach as a cross-check.

The gold standard is doing both, showing they land in the same order of magnitude, and being transparent about which inputs are assumptions vs. sourced.

The Australian data sources you should actually know

These are the sources AU investors will recognise and trust:

  • Australian Bureau of Statistics (ABS) — abs.gov.au. The foundational source for population, households, businesses by size and industry (ANZSIC), income, employment, and consumer spending. Free. "Counts of Australian Businesses" is the key dataset for B2B sizing.
  • IBISWorld Australia — paid, but sold in most university libraries and many coworking spaces. Gives industry revenue, growth, and concentration by ANZSIC code. This is what consultants quote.
  • Austrade and Export Finance Australia — useful for export market sizing and international comparables.
  • Reserve Bank of Australia (RBA) — macroeconomic data, payments data, lending figures.
  • ASBFEO (Australian Small Business and Family Enterprise Ombudsman) — aggregates ABS data into accessible small-business snapshots.
  • Roy Morgan and Nielsen — consumer behaviour and media usage; paid but often cited.
  • Industry regulators — APRA (financial services), AER (energy), ACMA (telco), TGA (therapeutics), Clean Energy Regulator. If you're in a regulated vertical, the regulator's annual report often contains the exact market figure you need.
  • Statista AU — aggregator; a fine starting point but not a primary source.
  • ASX company filings and broker reports — public-market incumbents reveal the shape of the market in their investor decks. If you're competing with a listed company, read their annual report before building your model.
  • State government data portals — data.nsw.gov.au, data.vic.gov.au, etc. Underused by founders.

One rule: cite primary sources wherever possible. "ABS Cat. no. 8165.0, June 2025" beats "according to a report we saw" every time.

Worked example 1: B2B SaaS (bottom-up, Australia-first)

Product: A compliance automation tool for allied health clinics (physio, psychology, dietetics).

Step 1 — Define the customer unit. Private allied health practices in Australia.

Step 2 — Count them. ABS + AHPRA registration data puts allied health practices at roughly 35,000 in Australia. Confirm with the relevant peak body (APA for physiotherapy, APS for psychology, etc.).

Step 3 — Define pricing. Target A$250/practice/month, based on 10 competitor benchmarks and 15 customer interviews.

Step 4 — Calculate SAM. 35,000 × A$250 × 12 = A$105M AU SAM.

Step 5 — Cross-check top-down. IBISWorld "Allied Health Services in Australia" puts the industry at ~A$20B in revenue. Software spend in healthcare is typically 1–2% of revenue, so ~A$200–400M. Our A$105M target is a plausible slice of that. Good — the two methods are in the same zone.

Step 6 — Expand to global TAM. Same methodology applied to OECD markets with similar healthcare structures (UK, Canada, NZ, Ireland, parts of the EU): roughly 20× the AU base. Global SAM ≈ A$2B.

Step 7 — SOM. Plan to serve NSW/VIC metro first (45% of AU practices), realistically win 8% in 3 years: 35,000 × 45% × 8% × A$250 × 12 = A$3.8M AU SOM by Year 3.

The pitch: AU beachhead is large enough to build a A$10M+ ARR business; global expansion unlocks A$100M+.

Worked example 2: Consumer mobile app (top-down cross-check)

Product: A budgeting app for Australians aged 25–45.

Step 1 — Define the audience. ABS: Australians aged 25–44 ≈ 7.8M people. Smartphone penetration ≈ 90% → ~7M reachable users.

Step 2 — Define monetisation. Freemium; target 8% conversion to A$7.99/month premium.

Step 3 — SAM. 7M × 8% × A$7.99 × 12 = A$53.7M AU SAM at steady-state penetration.

Step 4 — Honest reality check. That is a small SAM for a venture-backed consumer app. This is exactly the Australian founder's dilemma: the local market alone cannot fund a venture outcome. You need either (a) a clear international expansion path, (b) higher-monetisation B2B2C distribution (e.g. white-label to super funds or banks), or (c) a bootstrapped plan that doesn't require venture capital.

Step 5 — Global SAM. English-speaking markets (US + UK + Canada + NZ + Ireland) ≈ 150M people in the same age band. Same economics = ~A$1.15B. That's the slide that makes a seed round possible.

The honest lesson: sometimes the Australian number tells you your business is either a lifestyle business or a globally-scaled one. Investors want to know you've made that call deliberately.

The expansion ladder: AU → ANZ → APAC → global

A clean market-sizing slide for an AU startup usually reads as a staircase:

  1. Australia — bottom-up, credible, defensible. Your immediate GTM.
  2. ANZ — trivial extension for most SaaS; typically AU × 1.2.
  3. APAC / English-speaking — depends heavily on your product. SaaS into Singapore, HK, UK, and Ireland is plausible. SaaS requiring country-specific regulatory integration (tax, payroll, health) is not.
  4. Global — aspirational but supported by the same bottom-up method, just with country counts swapped in.

Each step should use the same methodology, with explicit assumptions about which changes (population, pricing, penetration, regulation) apply. Investors can tell when the global number was reverse-engineered from a round figure.

How Australian investors actually read the slide

Based on how Blackbird, AirTree, Square Peg, and others talk about this publicly:

  • They care about bottom-up SAM far more than TAM.
  • They want to see that you've personally talked to enough customers to know the pricing input is real.
  • AU-only businesses are fundable if the AU SAM is large (think: A$1B+ verticals like superannuation, logistics, construction, mining services).
  • For most software startups, they expect an AU beachhead with a clear global expansion path.
  • "1% of a big number" narratives are dismissed on sight. "We'll win 500 of 35,000 customers in 3 years because of X distribution advantage" is respected.
  • SOM is the number they'll hold you to. Be honest — an ambitious but defensible SOM beats a huge made-up one.

Pre-pitch checklist

Before your next deck update, run through this:

  1. Is TAM stated in annual revenue, not users or transactions?
  2. Is SAM calculated bottom-up and cross-checked top-down?
  3. Is the Australian customer unit defined and counted from a primary source (ABS, regulator, peak body)?
  4. Is the price point defended by specific customer interviews or comparable benchmarks?
  5. Does SOM specify a time horizon (3 or 5 years) and a plausible % of SAM?
  6. Is the growth rate of the market included, with a driver?
  7. Is the expansion path (AU → ANZ → global) shown as a ladder, not a leap?
  8. Are sources cited inline with dates?
  9. Have you stress-tested: if a sceptical investor halved every assumption, is the business still fundable?
  10. Does the number match the capital you're raising? (Rule of thumb: raising A$3M needs a SOM path to at least A$30M ARR; raising A$15M needs a path to A$100M+.)

Sources: Australian Bureau of Statistics (Population, June 2025; Counts of Australian Businesses, August 2025); ASBFEO Small Business Counts (August 2025); IBISWorld Australia; Reserve Bank of Australia. Figures current as of April 2026.