Choosing between a robo-advisor and a do-it-yourself (DIY) investing platform is, at its core, a decision about how much an investor wants to pay for someone else to make the underlying investment decisions. Robo-advisors typically build and manage a diversified portfolio automatically based on a short questionnaire, while DIY platforms simply provide the tools — an ISA or SIPP wrapper, a fund supermarket, dealing screens — and leave fund selection entirely to the investor. Both routes can be entirely reasonable; the right choice tends to depend on time, confidence, and how much the convenience is genuinely worth paying for.
How the two models differ in cost structure
Robo-advisors
A robo-advisor typically charges a single all-in percentage fee that bundles together the platform charge and a management fee for building and rebalancing the portfolio, often somewhere in the region of 0.25%–0.75% a year. On top of this, the underlying funds used within the robo-advisor's model portfolios (often low-cost index trackers or the provider's own in-house funds) carry their own ongoing charges figure (OCF), typically in the range of 0.10%–0.30%.
DIY platforms
A DIY platform charges only for the platform itself — commonly a percentage fee or flat fee as discussed elsewhere on this site — leaving the investor to select their own funds, each with its own separate OCF. There is no additional "management" layer charge, because the investor is doing that job themselves.
A worked hypothetical example
Suppose an investor has £30,000 to invest and is weighing a hypothetical robo-advisor against a hypothetical DIY platform, each held for one year with no further contributions or withdrawals:
| Cost component | Robo-advisor | DIY platform (self-selected tracker funds) |
|---|---|---|
| Platform/management fee | 0.55% (£165) | 0.25% (£75) |
| Underlying fund OCF | 0.20% (£60) | 0.12% (£36) |
| Total annual cost | 0.75% (£225) | 0.37% (£111) |
In this hypothetical example, the robo-advisor costs roughly £114 a year more than the DIY route on an identical £30,000 pot. Over many years, and especially as a pot grows through further contributions, that annual difference compounds meaningfully — but it needs to be weighed against what the robo-advisor is actually providing in return: automatic diversification, periodic rebalancing, and no need for the investor to research or choose funds themselves.
What investors are actually paying for with a robo-advisor
- Portfolio construction — selecting a diversified mix of asset classes and geographies appropriate to a stated risk level, without the investor needing to research this themselves.
- Automatic rebalancing — periodically buying and selling to bring the portfolio back to its target allocation as markets move, which many DIY investors either skip or do inconsistently.
- Simplicity — a single number (risk level or target date) determines the whole portfolio, reducing the number of decisions an investor has to make.
What DIY investors are trading for a lower fee
- Time spent researching and selecting funds.
- Responsibility for deciding on and maintaining a sensible asset allocation.
- Discipline to rebalance periodically, which is easy to postpone indefinitely without a prompt.
Who tends to find each approach a reasonable fit
Robo-advisors may suit
Investors who want a diversified portfolio without researching individual funds, who value not having to make ongoing decisions, or who are just starting out and want a simple, automated starting point. This may suit investors who would otherwise leave money uninvested or in cash for long periods simply because choosing funds feels daunting.
DIY platforms may suit
Investors comfortable choosing a small number of diversified funds (for example, a single global tracker fund, or a simple mix of a global equity fund and a bond fund), who are willing to review and rebalance periodically themselves, and for whom the lower ongoing cost outweighs the convenience of automation.
A middle ground
Some DIY platforms offer "ready-made" or multi-asset fund options — a single fund that itself holds a diversified, professionally managed mix of assets — which can replicate much of a robo-advisor's simplicity at a DIY platform's typically lower cost, since only one layer of fund-level charges applies rather than a separate platform-level management fee on top.
How the decision changes at different portfolio sizes
The pounds-and-pence cost gap between a robo-advisor and a DIY platform grows with portfolio size, in the same way any percentage-fee comparison does. On a very small portfolio — say a few thousand pounds — the difference between 0.75% and 0.37% might amount to only a few pounds a year, arguably not worth agonising over given the value of getting started with any diversified investment at all. On a much larger portfolio, built up over many years, the same percentage gap becomes a genuinely significant sum, and more DIY-minded investors often find the case for managing their own fund selection strengthens as their pot grows and the effort of research is spread over a larger base of assets. There's no fixed threshold at which one approach becomes objectively correct — it depends on the individual's confidence, available time, and the value they place on the convenience being offered.
Hybrid approaches worth considering
Some investors use a robo-advisor for a portion of their portfolio (for example, a pension they want to set and largely forget) while managing a DIY portfolio for another portion (such as an ISA where they enjoy researching and selecting individual funds). This isn't necessarily the cheapest approach in aggregate, but it illustrates that the choice needn't be all-or-nothing — different pots can reasonably be managed differently based on how much attention each one is likely to receive.
What to check when comparing specific robo-advisor providers
- Whether the stated management fee is genuinely all-in, or whether the underlying fund OCFs are charged separately on top and need to be added to get the true total cost.
- How many risk-based portfolio options are offered, and how they differ in underlying asset allocation — a wider range allows for a closer match to an individual's actual risk appetite and goals.
- How and how often rebalancing is carried out, and whether this is disclosed clearly rather than left vague.
- Whether the range of account types (ISA, SIPP, LISA, JISA) matches what the investor actually needs, since not every robo-advisor offers the full range.
- Whether there is a minimum investment amount, which can vary meaningfully between providers and matters for someone starting with a modest sum.
Comparing the true all-in cost
The fairest comparison is not the headline management fee alone, but the combined effect of platform fee, management fee (if any), and underlying fund OCF — sometimes called the total cost of investing. The companion article on calculating platform fee plus fund fee total cost sets out this calculation in more detail and applies equally whether the "fund fee" comes from a single ready-made fund, a robo-advisor's model portfolio, or a self-selected basket of individual funds.
Tax efficiency and rebalancing inside a robo-advisor
One less-discussed advantage some robo-advisors offer is that rebalancing is carried out within the tax-efficient structure the account already sits in — for example, inside an ISA, where switching between funds doesn't trigger a taxable disposal. A DIY investor manually rebalancing a General Investment Account, by contrast, needs to be mindful that selling one fund to buy another can realise a capital gain, potentially using up some of the £3,000 annual Capital Gains Tax exempt amount for 2025/26, or creating a CGT liability at 18% or 24% depending on the investor's income tax band. This isn't a reason in itself to prefer one approach over the other — the same consideration would apply to a DIY investor rebalancing inside their own ISA or SIPP without any tax consequence — but it's a factor specifically relevant to DIY rebalancing carried out in a taxable account, and worth being aware of before manually switching funds outside a tax wrapper.
Non-cost factors worth weighing alongside fees
- Range of account types — not every robo-advisor offers a full range of ISA, SIPP, and LISA wrappers; checking this against personal tax-wrapper needs matters as much as cost.
- Flexibility — DIY platforms typically allow holding any fund on their platform's fund list, while robo-advisors usually restrict investors to their own model portfolios.
- Behavioural fit — an automated approach that keeps an investor consistently invested through market volatility may, for some people, be worth more than the fee saved by managing things manually, particularly if the alternative is inconsistent contributions or panic-selling during a downturn.
How risk profiling works and its limitations
A robo-advisor's portfolio recommendation is typically generated from a short questionnaire covering an investor's time horizon, financial goals, and attitude to risk (often including questions about how the investor might react to a hypothetical market fall). This is a genuinely useful starting point, but it's worth recognising its limits: a short questionnaire cannot fully capture an individual's complete financial picture, including other assets, debts, or specific goals that might reasonably affect how a portfolio should be structured. Some robo-advisors periodically ask investors to retake or review the questionnaire, since risk tolerance and circumstances can change over time, particularly as retirement approaches and the appropriate balance of growth-seeking and capital-preserving assets often shifts, a theme covered in more depth in the companion article on de-risking a portfolio from equities to bonds over time.
Key takeaways
- Robo-advisors bundle portfolio construction and rebalancing into their fee; DIY platforms charge only for the platform, leaving fund selection to the investor.
- The combined cost of a robo-advisor (management fee plus underlying fund OCF) is typically higher than a comparable DIY tracker-fund portfolio, though the gap varies by provider.
- The extra cost of a robo-advisor pays for portfolio construction, automatic rebalancing, and simplicity — value that differs from investor to investor.
- Ready-made multi-asset funds on DIY platforms can offer a middle ground: broad diversification without a separate management-fee layer.
- Comparing the full all-in cost — platform fee, management fee, and underlying fund OCF together — gives a fairer picture than looking at any single charge in isolation.