How the Westwick family office cost calculator works
The Westwick family office cost calculator estimates what a single family office costs to run for a year, from its size, location, portfolio and the work it keeps in-house. It returns a central figure, a range and a breakdown across eight expense lines. The model is built from family offices our partners have set up and run, not from bank surveys. On request, it also prices what the family pays to invest. Current version: 1.6.0, October 2026.
What does the calculator estimate?
It estimates the cost of running a single family office for one year, in the currency you choose. You get a central figure with the range we see around it in practice, the same cost in basis points of assets under management, and eight expense lines with their share of the total.
The eight lines are management, the investment team, finance and operations, external providers, advisory and family services, IT and cybersecurity, concierge and lifestyle, and overhead.
That figure covers the office. What the family pays managers, funds, custodians and brokers is priced separately, in the full analysis described further down.
What do you need to tell it?
| Step | What it asks |
|---|---|
| 1. The office | Assets under management and currency (USD, GBP, EUR, CHF, JPY or CNY). The country where the office sits, from a list of fourteen, or "Other". How many family members it serves. How many jurisdictions the family and its structures are taxed in. |
| 2. The allocation | The share of assets in nine classes: public equities, fixed income, private equity funds, venture capital, direct investments, direct real assets, real asset funds, metals, commodities and crypto, and art and collectibles. Anything left unallocated counts as cash. If the family holds companies directly, how many, and how many it controls. |
| 3. The services | For investment oversight, execution on the listed portfolio, accounting and reporting, tax and legal, and IT: whether the office does the work or buys it. Whether it runs a philanthropy function and concierge services. Whether the family owns a jet, a helicopter, a yacht or holiday homes. |
Where do the figures come from?
From family offices our partners have built, reset and run from the inside. The model carries what those offices pay their people and their providers, and what it costs to keep the structure standing, country by country.
We read the bank surveys, but we don't build on them. Their samples choose themselves, and an average taken across offices of very different shapes tells you little about yours. What an office does moves its cost far more than how much it holds.
The benchmarks, ratios and factors inside the model are not published. If you want to see how your own figure was built, a partner will take you through it line by line.
What does the model assume?
Two offices holding the same assets can cost very different amounts. The services in scope, the seniority of the people and the complexity of the portfolio count for more than the size of the balance sheet, and the model is built around that.
Smaller families don't build a full team. They hire a few generalists, the principal stays close to investment decisions, and advice is bought on retainer. The model prices that arrangement as it is, rather than shrinking a large office to fit.
Where an office would, in practice, change the way it works as it grows, the model makes the change gradually. A modest rise in assets should not add or remove a whole salary.
Outsourcing gets more expensive as the office grows. For each profile there is a size at which doing the work in-house costs less than buying it, and the model shows where that falls. Whether to make the move also depends on control and on who holds the data, which is the family's call.
A company the family controls has to be run. A minority stake only has to be followed. The model staffs the two differently.
Salaries vary between countries far more than the fees of international providers do, so each gets its own country adjustment.
Lifestyle assets are priced at what they cost to keep each year, not at what they cost to buy.
What do bank surveys leave out?
Most published figures on what a family office costs stop at running the office. The family also pays to invest: management fees, costs embedded in funds, custody, trading and carried interest. Where the portfolio holds private market funds, that is often the larger amount, and it is rarely added up in one place for the principal.
The full analysis prices it on the portfolio you entered, under three return scenarios. Carried interest is spread over the life of the funds, with part of it following each scenario's return, instead of being charged on a single year's performance.
On the model's own outputs, the gap looks like this:
| Basis | Portfolio | Annual cost, % of assets |
|---|---|---|
| Survey-based estimate, "all-in" | — | around 0.5–0.75% |
| Westwick model, fully costed | $500m, close to a third in private market funds | around 1.5–2% |
| Westwick model, fully costed | $500m, entirely listed | around 0.8% |
The family is already paying the difference. It has usually never seen it in one figure.
Why a range and not a single number?
Two families of the same size can differ by half again in cost, because of choices no model can see: how senior the hires are, the standard the principal expects, the work the office takes on without anyone writing it down. The range carries that.
What you get is an estimate. It is a fair way to check whether what you pay today holds up, and to open the conversation with your family office executives. A budget needs the detail of your own office; our partners can build one with you.
Currency and exchange rates
The model calculates in US dollars and converts at fixed rates, so the same profile gives the same answer from one day to the next. The rates in use date from 1 June 2026 and are updated periodically.
Model versions
Every change to the model is versioned.
| Version | Date | What changed |
|---|---|---|
| 0.3 | March 2026 | External provider fees revised upwards after review by the partners |
| 0.4 | April 2026 | Staffing rules set by the partners replace a generic mapping of services to roles |
| 0.5 | May 2026 | Teams modelled by seniority; pay adjusted by the country where the office sits |
| 1.0 | 10 June 2026 | First audited version of the model |
| 1.1 | August 2026 | Smaller offices priced as lean offices, outsourced services priced to rise with size, separate country adjustments for salaries and providers |
| 1.2 | August 2026 | Private holdings staffed on their value; controlled companies and minority stakes treated apart |
| 1.3 | August 2026 | Transitions smoothed, so that no small step in assets adds a whole post |
| 1.4 | August 2026 | The model returns amounts only; no staffing detail or rate leaves it |
| 1.5 | 30 September 2026 | Performance fees now differ across the three return scenarios |
| 1.6 | October 2026 | Belgium added to the countries covered |
What happens to your answers?
When you run an estimate, we record the figures entered, the result, and an approximate location taken from the connection. We don't keep your IP address; it is replaced by a one-way fingerprint. The records carry no name or contact detail, are never used for marketing, and are deleted after twelve months. We may publish findings in aggregate, never anything that identifies an estimate, a visitor or a family. The details are in our company policy.
Each connection can run fifteen estimates a day. The full analysis is prepared on request: we review your answers, then send it by email.
Offering the calculator to your own clients
Banks, providers and platforms can put the operating estimate in front of their clients through our API or an embedded version. Write to contact@westwick.org.uk.
Frequently asked questions
How much does a single family office cost to run?
It depends mainly on what the office does, how senior its people are and how complex the portfolio is, more than on its size. As an illustration, the model puts a UK office managing $500m, with half its assets listed, close to a third in private and real asset funds and a tenth in direct holdings, at roughly $3.3m a year to run. The calculator gives the figure for your own profile.
Does the calculator include investment fees?
The operating estimate does not. The full analysis, sent on request, prices manager and fund fees, custody, trading and carried interest on your portfolio under three return scenarios.
Is the calculator based on bank surveys?
No. It is built from family offices Westwick's partners have set up and run. We read the surveys, but self-selected samples and averages across very different offices say little about any one office.
How precise is the estimate?
It comes with a range, because two offices of the same size can differ by half again on choices no model sees. It is an estimate for testing what you pay, not a budget.
Which countries does it cover?
Belgium, Canada, China, France, Germany, Hong Kong, Japan, Luxembourg, Monaco, Singapore, Switzerland, the United Arab Emirates, the United Kingdom and the United States. Offices elsewhere are priced on a major financial centre.
Is it free to use?
Yes. Anyone can run up to fifteen estimates a day without registering. The full analysis asks for a name and an email address.