Tick Size and Minimum Orders: Why Price or Size Is Rejected

If your price looks correct and the balance is sufficient but the order is rejected, the price or quantity may not match the exchange's permitted increments. Here is a numerical explanation of tick sizes and minimum orders.

Exchanges do not accept every possible number

Each market uses a defined grid for prices and quantities. An order must fall exactly on that grid. Otherwise, the issue is not a missed fill: the order itself is rejected.

Common error messages include:

These point to increment or minimum-size rules rather than simply an empty balance. Four rules explain the main cases.

① Tick size: the minimum price increment

Tick size is the smallest permitted price increment and determines which prices you can enter in a limit order. It is the same basic concept as a stock market's quotation increment.

Low-priced altcoins can have much smaller ticks. A 0.00001 tick allows five decimal places, while a tick of 1 permits no fractional price. The key is that each market differs.

This often arises when pasting a calculated stop or target. An entry price minus 1.5% might produce 61,376.85, but with a 0.1 tick it must be rounded down or up to 61,376.8 or 61,376.9.

② Step size or lot size: the quantity increment

Quantity has the same kind of rule. Step size, also called lot size here, is the increment by which quantity can increase or decrease.

An attempted full-balance purchase can fail here. Dividing balance by price may produce 0.0234718..., which does not match the step. For that maximum-affordable calculation, round down to 0.023. Rounding up can cause an insufficient-balance rejection.

③ Minimum quantity and ④ minimum order value

Even a correctly aligned order is rejected if it is too small. There are two separate lower limits.

Minimum quantity specifies the minimum number of units. Minimum notional specifies the minimum total order value. Failing either requirement can cause rejection.

Low-priced coins are particularly likely to hit the minimum value requirement. That is why buying just one coin may be impossible.

A futures complication: contract quantity

Some futures and perpetual markets accept quantity in coins; others use contracts. For contract-based orders, each market specifies how much asset one contract represents.

At fixed quantity, leverage does not change notional. It changes required margin. At 20×, margin is $3,100 ÷ 20 = $155, but exposure remains $3,100. Confusing them can make losses seem unexpectedly large relative to the posted amount.

Why these increments exist

Infinitely small price increments would scatter orders across an unreadable order book. A price grid concentrates liquidity so bids and asks can meet meaningfully. Minimum notional rules also prevent tiny dust orders from filling servers.

However, an overly large tick can widen the spread and raise slippage costs, contributing to poor market-order execution in thin altcoins.

Practical checklist

1. Before trading a new market, check tick size, minimum quantity and minimum value. These usually appear near the order panel or under Contract Info or Trading Rules.
2. Align calculated prices to multiples of the tick. Automated trading code also needs this rounding.
3. For the affordable-quantity calculation described here, round quantity down to avoid exceeding the balance.
4. Read the exact error message before assuming insufficient funds. It identifies price, size or notional.
5. Orders with two prices, such as a stop-limit, require both prices to align with the tick.

If limit, market and conditional orders are still confusing, read order types first. The fee calculator explains costs on executed value.

Three key points

① Tick size controls price increments; step size controls quantity increments. Nonmultiples can be rejected before entering the book.
② Minimum quantity and minimum notional are separate conditions. Low-priced coins often hit the value requirement first.
③ The guide aligns prices in its chosen trade direction and rounds affordable quantity down.

Caution

The figures are examples. Actual rules differ by exchange, market and date. Check the relevant market information before trading. Decisions and their consequences remain your responsibility.