Overall score
Our overall score is based on a combination of customer score, fees score, and assets score.
We don’t analyse the performance of investments listed by investment platforms, as different investors will opt for different investments.
Customer score and ratings
We surveyed 3,053 investors – members of the Which? Connect panel and of the public – who gave 4,146 reviews of stocks and shares Isas in January 2026.
Each platform must get at least 30 responses to receive a customer score, which is based on overall satisfaction and likelihood to recommend.
The customer score makes up 60% of the overall score.
We also ask investors to rate their current platform for customer service, ease of use, information on investments, and value for money.
Fees score
The fees score uses snapshots of account and transaction fees at £5,000, £10,000, £25,000, £50,000, £100,000, £250,000, and £500,000. The fees assume four purchases and four sales in a year, spaced out in across months.
Fees are weighted higher closer to £50,000 as this is close to the average portfolio size, according to HMRC data.
The scores are assigned relative to the cheapest platform which would receive a score of 100%.
The fees score makes up 30% of the overall score.
Assets score
The assets score adds together all of the assets available within a stocks and shares Isa and assigns a score relative to the maximum out of the providers which receives 100%.
The assets score makes up 10% of the overall score.