Start with money out and assets in
One quote says no fee. Another lists a service charge. Neither label tells you which delivers more for your money. Start with two quantities: the total leaving your payment account and the net amount of the same asset reaching the destination.
Divide the first by the second. That is the effective unit cost. It reflects the quoted price and included deductions together; it does not measure the exchange’s profit or replace a market price.
Count each charge once
If a quote says “pay 1,000 GEL, receive 365 USDT”, record those figures first. A bank charge of 10 GEL paid on top makes total spend 1,010 GEL. If a crypto fee has already been deducted to produce the 365 USDT net figure, do not subtract it again.
A fee paid in a different asset needs conversion into your payment currency at a chosen, consistent time.
Keep the conversion source. Without it, adding amounts denominated in different currencies produces a meaningless total.
A calculation you can reproduce
These are invented teaching figures, not current GEL prices. Quote A asks for 1,000 GEL, with 10 GEL paid separately, and delivers 365 USDT. Quote B asks for 1,000 GEL, has no extra charge and delivers 368 USDT.
B: 1,000 ÷ 368 ≈ 2.7174 GEL / USDT
B has the lower unit cost in this example. The quantities differ, so this does not establish a guaranteed cash saving on an equal-sized order. Minimum orders and tiered charges may change a new quote.
Only 1,000 GEL to spend? Check the budget first
“Lower unit cost” and “enough money to pay” are separate questions. Quote A above requires 1,010 GEL. If your entire budget is 1,000 GEL, that quote is already outside it. Enter your actual budget in both purchase routes and obtain executable quotes before comparing the quantities received.
Do not simply scale the 1,010 GEL quote down to 1,000 GEL. Minimum orders, fixed charges and price tiers can change the smaller order. Comparing complete quotes is more reliable than guessing the price of an order you have not requested.
If instead you need exactly 365 USDT, request that quantity from both routes and compare the total payments. Buying as much as possible for a budget and paying as little as possible for a fixed quantity are different tasks. Keep the question consistent throughout your comparison.
Which number gets the 20% fee reduction?
The eligible fee, not the purchase principal. Suppose a covered trading fee is 10 GEL. A 20% reduction makes it 8 GEL, saving 2 GEL. The 10 GEL fee is hypothetical, not a Binance rate.
Fee saving: 10 − 8 = 2 GEL
Do not multiply a 1,000 GEL purchase principal by 80%, or assume separate bank charges also shrink. If a benefit is already reflected in the final payment or net received quantity, use the displayed figures without another deduction. When fees are charged first and rebated later, record the actual payment and check the rebate separately after it arrives.
A task voucher’s face value is not an immediate discount on this order either. Product coverage, rebate percentage and expiry may affect what you can use. Leave unearned rewards out of the quote calculation so the result can be checked against real records.
Define where the asset must be usable
An account credit and delivery to an external wallet are different endpoints. Write down which one your purchase must reach. If you are comparing account credits, a withdrawal you have not planned does not belong in the quantity yet. If you need wallet delivery, check the actual network, recipient requirements, minimum and net withdrawal quantity for both routes.
Suppose one quote delivers 100 units to an exchange account while another delivers 99 to a wallet. Dividing their payments by these quantities does not compare delivery to the same place. Complete the first route with its actual withdrawal conditions, or compare both routes at the account stage. If those conditions are unavailable, record the account-level result and leave wallet delivery unresolved. The delivery guide walks through that boundary.
The endpoint also limits the conclusion. A lower purchase unit cost does not establish convenient withdrawals, reliable service or lower costs on every network. Those questions need their own evidence rather than an invented risk surcharge added to the calculator.
A percentage saving needs a named denominator
Using the homepage's hypothetical example, A costs 1,010 divided by 365 per unit; B costs 1,000 divided by 368. To describe B as cheaper than A, subtract B's unit cost from A's and divide by A's. The result is approximately 1.8%. Saying A is more expensive than B uses B as the denominator and produces a slightly different percentage.
The calculator reports the lower unit cost relative to the other quote. It does not promise the cash saving from buying an identical quantity because order minimums, fixed charges and size-dependent quotes may differ. For a cash difference, obtain executable offers delivering the same net quantity and subtract their total spending. The budget and quantity guide explains the two questions.
Keep sufficient precision while calculating and round at the end. Rounding both prices too early can hide a small difference. Conversely, displaying eight decimal places does not make an expiring quote more certain: arithmetic precision and quote validity remain separate.
Unknown outside charges can reverse the ranking
A bank conversion may not have settled when you first compare a purchase. Record the known order amount and net quantity, leaving final local-currency spending pending. You can calculate in the quote currency or show an explicitly assumed estimate, but you cannot call that estimate the settled payment.
Consider equal received quantities with A's confirmed spending at 1,000 and B's order amount at 998 plus an unknown outside charge.
B has only 2 of cost headroom. An additional charge above 2 reverses the apparent ranking. That number is a break-even difference, not a forecast of the bank's tariff.
Ask the charging party whether anything is payable beyond the displayed total, in which currency it settles and where the final record will appear. If the fee cannot be established before purchase, that uncertainty belongs in the comparison. It is not a reason to enter zero. For a completed payment, see the card-statement check.
Repeated payments and fills need quantity weights
Fixed charges change with the number of charged events. Under an explicitly constant-price assumption, two orders with a separate charge of 4 each incur 8, while one order incurs 4. That arithmetic does not establish the actual larger-order price or justify adding money you did not intend to spend. Count the charges for the plan you already considered; see the fixed-fee guide.
For completed purchases, divide combined spending by combined net quantity.
In an invented example, one purchase costs 200 and delivers 100 units, while another costs 900 and delivers 300. Combined cost is 1,100 divided by 400, or 2.75. The simple average of their unit costs, 2 and 3, would be 2.5 and would underweight the larger purchase.
Several executions within one order require the same quantity weighting, followed by the correct treatment of fees. The partial-fill guide separates execution price, unfilled quantity and net receipt. Never add an order summary to its own underlying fills.
Keep the quote and the completed result as separate records
Changing the payment method, amount or quote time may replace the original paired values. Do not combine a new payment with an old, more attractive received quantity. Save each pair together with its time and status. The quote-refresh guide separates preview, acceptance and the final record.
After a purchase, add actual spending and the matching asset credit beside the estimate. Do not overwrite the estimate and make it appear that the final result was known beforehand. If a later bank charge becomes clear, update the actual column once and retain its source. For every deduction, check whether it is already inside the payment or net receipt; the fee-currency examples show where duplication occurs.
A useful saved comparison names its currency, asset, endpoint, time and unresolved conditions. It can conclude that one executable quote has a lower observed unit cost while another needs a payment condition clarified. It cannot establish future returns or convert an unsupported payment method into a usable one.
A lower number is not the whole decision
Collect quotes close together in time, using the same currency, asset and delivery destination. An exchange balance and delivery to an external wallet are different endpoints. Include withdrawal costs if the latter is what you need.
Then check expiry, limits, who receives payment and whether you can use the method. A lower unit cost does not establish safety. If the confirmation screen refreshes the quote, recalculate using the new figures instead of relying on an expired comparison.