Investment fees calculator
Investment fees calculator: what do fees really cost?
Compare a platform that charges a percentage of your pot with one that charges a flat monthly fee, both holding the same fund, and see the cost over the years, including the growth the fees take with them.
What do fees really cost?
Compare a platform that charges a percentage of your pot with one that charges a flat monthly fee, both holding the same fund. Small numbers, compounded for decades, become big ones.
Your numbers
Option A: percentage platform
Option B: flat-fee platform
Illustrative value after 25 years
A · Percentage fee
£0
B · Flat fee
£0
How to read this
Charges are taken monthly from the pot, so every pound paid in fees also stops earning growth for the rest of the period. That is why the true cost is far bigger than the fees you can see on a statement. Percentage fees tend to suit smaller pots and flat fees larger ones; where the line falls depends on your numbers. More on this in why fees decide your returns.
How it works
Why small fees become large ones
A fee of 0.45% a year looks tiny. But it’s charged on the whole pot, every year, and each pound taken in fees also stops earning returns for every year after. Over 25 years the total cost is usually several times the fees you see on your statements.
The hidden cost
The fees on your statement are only part of it. The rest is the growth those pounds would have earned if they’d stayed invested.
That hidden part is what the difference between the two options shows.
Percentage or flat fee
A percentage fee grows as your pot grows, so it’s cheap when you start and expensive later. A flat fee stays the same, so it’s relatively expensive on a small pot and cheap on a large one.
Where the crossover falls depends on your numbers.
The fund charge
The fund charge, often shown as the OCF (ongoing charges figure), is paid on top of the platform fee in both cases.
A low-cost index fund might charge 0.1% to 0.25% a year; some actively managed funds charge 0.75% or more.
Questions
Common questions
Quick answers about the figures. For your own circumstances, gov.uk and your provider have the details.
Are the platform fees here real prices?
No. They’re example figures. Platforms change their charges, so check the current price list of any platform you’re considering and put those figures in.
Does it include trading charges?
No. Some platforms charge to buy or sell, and some charge nothing for regular monthly investing. If you trade often, those charges add up too.
Does moving platform cost anything?
Most platforms no longer charge to transfer out, but check before you move. A transfer done properly doesn’t use any of your ISA allowance, as I explain in how to transfer an ISA.
Other calculators
New to ISAs?
Read the sixteen articles in order.
Getting Started takes you from the basics to opening your ISA, then the principles that keep you invested and how wealth builds over time.
Go to Getting StartedAll results are illustrations, not forecasts, and not financial advice. They assume steady rates that real markets never deliver. The value of investments can go down as well as up, and you can get back less than you put in. Allowances, tax rates and ISA rules can change, so always check gov.uk for the current figures.
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