Every perpetual futures contract on a crypto exchange comes with a specification sheet — a dense block of numbers that tells you exactly what you're signing up for. Most traders skip it. That's a mistake, because the difference between a profitable trade and a liquidated one often hides… This is educational content about how the mechanics work — never a trade recommendation.
What contract specifications actually cover
Contract specs are the exchange's legal definition of what a derivatives product does. On OKX, you'll find them under the "Contract Info" tab for each perpetual. On Binance, it's the "Rule Details" page. The layout differs, but the data points are the same.
Here's what matters:
- Contract size — how much of the underlying one contract represents. OKX's BTCUSDT perpetual uses 0.01 BTC per contract. MEXC's BTCUSD coin-margined contract uses a fixed $100 face value.
- Tick size — the minimum price increment. For BTC perps this is usually $0.10 or $0.50. Placing an order between ticks gets rejected or rounded.
- Funding interval — how often funding settles. Standard is 8 hours. When rates hit the cap (typically ±2% on OKX), Binance and OKX both switch to hourly settlement, meaning 8x the cost in a single day.
- Price limits — the maximum percentage a contract can move in one settlement cycle. This varies by tier.
These aren't abstract numbers. They directly determine your holding costs, your maximum position, and when the liquidation engine kicks in.
Margin tiers: the part everyone misses
Here's where most traders get blindsided. Exchanges don't apply a single leverage limit to all positions — they use tiered margin requirements that tighten as your position grows.
On OKX, a BTCUSDT perpetual under 500 contracts might allow 100x leverage. Push past 500 contracts and you drop to 50x. Beyond 2,000 contracts, it's 20x. The tiers are published in the spec sheet, but almost nobody reads them before opening a position.
Why this matters: if you build up a large position at 100x and then cross a tier boundary, your required margin jumps — potentially triggering a margin call even if the price hasn't moved against you.
| Position size (BTCUSDT) | Max leverage | Maintenance margin rate |
|---|---|---|
| Under 500 contracts | 100x | 0.5% |
| 500–2,000 | 50x | 1.0% |
| 2,000–5,000 | 20x | 1.5% |
| Over 5,000 | 10x | 2.0% |
Binance uses a similar structure. MEXC caps coin-margined leverage at 125x across the board but still adjusts maintenance margin by position size. The lesson is the same: read the tier table before you size up.
Funding rate mechanics hidden in the fine print
The contract spec also defines how funding works — and this is where costs can silently eat your margin.
Standard funding settles every 8 hours at rates set by the exchange's formula (usually a weighted average of the perpetual premium and an interest rate component). But here's the catch most traders miss:
When the funding rate hits the exchange's published cap or floor (OKX caps at ±2%, Binance at ±3%), the settlement frequency can shift. OKX switches to hourly funding. That means instead of paying 3 times a day, you're paying 24 times.
The spec sheet also tells you which price index the contract uses for funding calculations and liquidation triggers. OKX uses a mark price constructed from multiple spot exchanges. Binance does the same. The specific exchange composition varies — and during a flash crash on any single venue, it can affect whether your position gets liquidated.
A practical checklist for reading any spec sheet
Here's the order I go through when checking a new contract. Takes about 3 minutes:
- Contract size and face value — what's one contract worth?
- Tick size — am I placing orders at valid price increments?
- Settlement currency — USDT or the coin itself? This affects how fees are charged.
- Maximum leverage at my intended position size — check the tier table, not just the advertised "up to 100x"
- Maintenance margin rate at my tier — this is your real liquidation threshold
- Funding interval and rate cap — what's my worst-case holding cost per day?
- Liquidation method — partial or full? Does the exchange use ADL (auto-deleveraging)?
- Trading hours and maintenance windows — when can the exchange halt trading?
It sounds tedious. It's not. Once you've read a few spec sheets, you'll spot the differences between exchanges in minutes. And you'll avoid the "how did I get liquidated?" moments that come from not knowing the rules of the game you're playing.
For a walkthrough of the liquidation process itself, check our liquidation mechanics guide. And if you want to calculate exact holding costs, try our funding rate calculator.
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