Start from "losing all of this would change nothing for me" and work down, rather than up from "I want to make X". Fill in three numbers and you get a suggested range and a view of what costs look like at that size.

This is a ruler, not an answer. The final number is yours, and erring on the conservative side is the right instinct.

Amount I could lose entirely without it mattering

The pair's minimum order value

Withdrawal fee, converted (0 if not withdrawing)

100

suggested first trade (half of what you can absorb)

Lower bound of the usable range5.00
Upper bound of the usable range200.00
Withdrawal fee as a share of that size0.00%
One round trip of trading fees (at 0.1% one way)0.20%

Make sure you could genuinely accept this going to zero before moving on.

Computed in your browser; the numbers you type never leave this device. This tool is not investment advice.

How the ruler works and why it halves the number

What problem it solves

"Only risk what you can afford to lose" is true and unusable. This breaks it into steps you can fill in, and adds the constraint people forget — the share taken by a fixed withdrawal fee.

Why the suggestion is half your ceiling

Because the first trade should not consume your entire tolerance. There will be a second and a third, and you may want room to act during a dip. Keeping the first within half leaves you able to continue.

Where the lower bound comes from

It is the pair's minimum order value, below which the system refuses the order. If the amount you can absorb is already under that threshold, the conclusion is not "increase the size" — it is to re-examine whether this money is genuinely expendable. A platform threshold is not a reason to risk more.

Reading the withdrawal share

Withdrawal fees are fixed quantities per coin and network, so the smaller your balance the larger the share. If that share exceeds one or two percent, the usual answer is to accumulate before withdrawing, or to pick a cheaper network — not to raise the stake. Leave the field at zero if you are not moving the asset on-chain.

Where the data comes from

This page does not fetch anything from the internet. The trading-fee line uses a fixed assumption of 0.1% one way over one round trip purely for scale; for your real rate, use the cost calculator with the figure from your own fee page. The numbers already filled in are only examples, not any exchange's current parameters.

Who it is for

People who have drilled the demo account and are preparing a first real trade. If the readiness checklist is not full yet, this can wait — size is the last question, not the first.

First-trade size ruler