# Buying a Fraction: Order Types Without the Jargon

URL: https://www.xineee.net/fractional-order-types/
Published: 2026-10-27T23:21:24+00:00 | Updated: 2026-10-27T23:21:24+00:00
Verified: 2026-10-27

## Quick answer
Crypto order types are rules about how an order reaches the market. Market orders trade price certainty for a fill; limit orders trade a fill for price certainty.

## Summary
Market orders buy certainty of fill, limit orders buy certainty of price. Here is what each crypto order type commits to, plus the arithmetic of buying a fraction.

## FAQ
Q: Do order types work the same on every venue?
A: No. Market and limit orders are near-universal, but stop triggers, time-in-force options and post-only rules vary by platform. Some venues implement a stop as a market order; others need a separate trigger service. Read the documentation before trusting a label.
Q: Can a limit order fill at a better price than my limit?
A: Yes. A buy limit at 2.00 can fill at 1.98 if the book gaps down through your price, because your order becomes the best bid and takes the better offer. The limit is a ceiling, never a floor.
Q: Is a stop-loss a guaranteed exit?
A: No. It becomes a market or limit order once a trigger prints, so in a gap or a thin book the fill can be far below the trigger, and on a stop-limit it may not happen at all. A stop defines an intention, not a price.
Q: Why did my post-only order get rejected?
A: It would have crossed the spread when it reached the matching engine. Post-only exists to stop you paying taker fees, so the venue refuses the order rather than letting it execute. Reprice slightly away from the touch and resubmit.
Q: What does time-in-force actually change?
A: How long an unfilled order stays alive. A day order expires at the session boundary, good-till-cancelled persists, and immediate-or-cancel dies on arrival.
Q: Should a first purchase use a market order or a limit order?
A: For a small first purchase on a deep pair, a marketable limit placed just inside the spread gives a fill with a hard ceiling on price. Both failure modes stay visible: you either fill, or you watch the order sit unfilled.