Investment Platform Fee Comparison Calculator – ISA, SIPP & GIA

How this calculator works

Who this is for: self-directed investing

This tool compares self-directed (DIY) platforms, where you choose your own investments and the platform simply holds them and handles your trades. It does not cover managed or “robo” services that pick and run a portfolio for you, or financial advice. Those add a management or advice fee on top of the platform cost, often 0.5% to 0.75% a year or more, so their charges are not comparable like-for-like with a DIY platform. If you would rather someone else chose your investments, a managed service may suit you better, just expect to pay more for it. For free, impartial help deciding, MoneyHelper is a good government-backed starting point.

Fee calculation method

Costs are worked out month by month on your actual balance, so platform fees reflect the contributions you add through the year, not just your starting pot. By default no investment growth is assumed; the advanced options let you add an expected growth rate and a multi-year time horizon to project costs into the future.

What’s included

Calculations cover the three costs the platform itself charges you: platform (account) administration fees, trading and dealing fees, and FX (currency conversion) fees on non-GBP investments such as US shares. Free regular-investing deals are applied where a platform offers them for your selected investment type, and frequent-trader discounts where available.

What’s not included

Fund management charges (OCF/TER) are not included. You pay these to the fund manager whatever platform you hold the fund on, so they don’t change the comparison between platforms. Exit and transfer fees, and conditional discounts such as loyalty bonuses, account bundles or fund-specific deals, are also not modelled.

Limitations

Platform fee structures are interpreted from each provider’s published documentation, and complex tiered structures may carry minor calculation variances. Not every UK provider is included. Results are estimated annual costs based on current published rates, which may change without notice.

Important information

This is a fee comparison tool, not investment advice. Always verify current fees, terms and conditions directly with the provider before opening an account. Every platform here is authorised by the Financial Conduct Authority, and you can check any firm on the FCA register. The value of investments can go down as well as up, and you may get back less than you invest. ISA and pension rules and annual allowances are set by the government and may change.

Data accuracy

Fee information is based on providers’ published rates and is updated regularly. Platform features, investment options and account terms vary between providers, so check provider websites for complete details before making investment decisions.

Which platform is cheapest for you?

There is no single cheapest platform. It comes down to how much you hold and how you invest, which is exactly what the calculator above works out for your own numbers. A few patterns are worth knowing, though.

Fee-free platforms usually win on cost

A handful of platforms charge no account fee at all: Trading 212, InvestEngine, Freetrade, Lightyear, Prosper and IG. For most people these come out cheapest outright, and the gap only grows the bigger your pot, since a percentage fee would otherwise take more and more. They make their money another way, through currency conversion, interest on your cash or paid-for extras, so it is worth a quick look at how before signing up. Several also run welcome offers you can find on our free share offers page.

The trade-offs on an ISA or General Investment Account

Cheaper is not automatically better for you, so it pays to know where fee-free platforms make their money back. They tend to offer a narrower menu of investments, so if you want a particular fund or investment trust, check it is on the list before you switch. Many earn their keep on currency conversion, which means buying US or other overseas shares can cost more than it first looks. And some keep part of the interest on the cash sitting in your account rather than passing all of it on to you. Support also tends to be app-based, with little or no phone service. For most straightforward index investors none of this is a dealbreaker, but it is worth a look if you hold a lot of overseas shares, keep a large cash balance, or want the widest possible fund choice.

The bigger catch: pensions you will draw on later

If you are picking a SIPP that you will one day take an income from, look before you leap on the fee-free ones. Several are built for growing a pot, not taking money out of it. Trading 212’s SIPP, for instance, has no drawdown facility at all and is accumulation only. Years from retirement that does not matter. Close to it, you will want a platform that offers flexi-access drawdown, or you will have to transfer your pension out later to start drawing an income, which is a hassle you can avoid by choosing well now. Pension Wise, part of MoneyHelper, offers free government-backed guidance on your retirement options.

Why how often you trade changes the answer

Here is the thing almost every “cheapest platform” table quietly hides: the answer depends on how often you buy and sell, not just how much you hold. There are really two kinds of investor.

Buy and hold. You pay into a few funds or ETFs each month, usually through free regular investing, and you rarely sell. Almost all of your cost is the platform’s account fee, so the cheapest options are the fee-free platforms, or a flat-fee one that lets you invest regularly for free. This is how most index investors behave, and it is what this calculator assumes by default.

Active trading. You buy and sell more often, maybe picking individual shares or rebalancing through the year. Now dealing fees matter as much as the account fee. A platform that looks cheap on a flat fee can work out dear if it charges, say, £9.50 a trade, while a platform that caps its percentage fee and offers cheap dealing pulls ahead.

That is why our numbers can differ from a table that silently assumes you trade every month. If you do more than the odd trade, open the advanced options and set One-off trades a year to match how you actually invest. The ranking then reflects your behaviour, not someone else’s assumption.

If you would rather pay a fee directly

Some people prefer to pay a platform fee directly, or want something the free platforms do not offer. Among the platforms that charge, the cheapest choice depends on two things: how big your pot is, and what you hold in it.

A Stocks and Shares ISA or General Investment Account. Scottish Widows is usually cheapest whatever you hold, because it charges no platform fee at all, just £5 a trade. Interactive Investor’s flat fee is the main alternative once your pot runs into six figures.

A SIPP in ETFs or individual shares. Here the percentage-fee platforms cap what they charge (Fidelity and AJ Bell both cap a SIPP at around £140 a year), so a capped platform tends to win on a larger pot. As a rough guide:

• Vanguard up to around £55,000 (its own ETFs only; it does not offer individual shares)
• Interactive Investor from about £55,000 to £100,000
• Fidelity or AJ Bell above £100,000

A SIPP in funds. Most percentage platforms do not cap their fee on funds, so it keeps climbing as your pot grows. That leaves two front-runners: Vanguard on smaller pots (its 0.15% charge is capped at £375 a year), and Interactive Investor’s flat fee once you are into a large six-figure balance. The capped-ETF bargains, Fidelity and AJ Bell, are not the cheapest for funds.

These are rules of thumb; the calculator above gives you the exact crossover for your own portfolio and the way you invest.

Our data and independence

Every platform’s fee structure is held as structured data, and the costs are worked out with the same engine that powers the calculator, so the figures you read and the rankings you see always match. We update the data whenever a platform changes its pricing, and the comments and updates log further down records each change with the date it happened.

We do not take payment for rankings. Results are always sorted cheapest first. Platforms marked Spotlight are commercial partners, but they are only ever nudged up when two options cost exactly the same, never ahead of a cheaper one. We also leave out fund charges (the OCF), because you pay those whatever platform you hold the fund on, so they would not change which platform is cheapest. Figures come from each provider’s published rate card and are estimates, so always check the current terms before opening an account.