A calculator that does not show its working is a black box, and a seller handing figures to a client deserves better than that. This page sets out exactly what the sheet does with each number you give it, in the order it does it, so you can check the output by hand or explain it to somebody across a kitchen table.
Step one: the fee itself
A commission is the sale price multiplied by the rate, so a rate expressed as a percentage becomes a pound figure the moment a price is entered. A fixed fee is simply itself. The sheet takes both, because agents quote both and some quote a fixed fee with a percentage above a threshold, and it keeps them as separate inputs so that two quotes stated in different forms can be compared on one screen rather than on the back of an envelope.
Step two: VAT, applied only where it belongs
VAT at the standard rate of 20 percent applies to the agency fee. It does not apply to the mortgage you are redeeming, and treating the whole sheet as VATable is a common and expensive slip. So the sheet applies the rate to the fee line alone and shows the VAT as its own row rather than folding it into the fee. If your quote was already inclusive, you enter it as inclusive and the row reads zero, which keeps the two forms of quote directly comparable.
Step three: the fixed lines and the redemption
Conveyancing, the energy certificate and removals are entered as pound figures because that is how they are quoted, and they are summed without adjustment. The outstanding mortgage is subtracted last, after the costs, because it is not a cost of selling at all: it is your own borrowing being repaid out of the proceeds. Keeping it separate is what makes the final row mean something, because it distinguishes what the sale cost you from what the sale leaves you.
The row that matters
Sale price, less fee, less VAT on the fee, less the fixed lines, less the mortgage redeemed, is the seller's net proceeds. Every other row on the sheet exists to make that one defensible. It is the figure that decides whether the next purchase works, and it is the one worth running twice: once at the asking price and once at the price you would actually accept.
Questions people ask about estate agent fee calculator
Does the sheet include stamp duty?
No. Stamp duty is paid by a buyer, not a seller. If you are buying as well, that is a separate sum and not part of what selling costs you.
Why is the mortgage subtracted after the costs?
Because redeeming a loan is not a cost of selling. Keeping it below the cost lines lets the sheet show both what the sale cost and what it leaves.
Can I compare a fixed fee and a commission in one go?
Yes. Enter each quote in turn at the same sale price. The crossover point is the price at which the two answers meet.