How the BloFin ETHUSDT perp order box actually counts your size: 1 contract = 0.01 ETH

[Trading setup] If you type 1 into the size box on BloFin's ETHUSDT perpetual and think you bought 1 ETH, you bought 0.01 ETH. BloFin's public instrument data lists the ETH-USDT swap with a contract value of 0.01 ETH, a minimum size of 0.1 contracts, a lot step of 0.1 and a price tick of 0.01. Getting that unit right is step one of setting up a first trade.

The image is BloFin's live ETHUSDT perpetual page this afternoon, with the price header, chart and order book.

Setting up the order, in the order you actually click it:

1. Margin mode. Isolated keeps the loss on this position to the margin you put in it. Cross lets the position draw on your whole futures balance. For a first trade, isolated is the easier one to reason about.
2. Leverage. BloFin allows up to 150x on ETH-USDT. Leverage does not change how much ETH you hold; it changes how much margin you post for it.
3. Size. Decide in ETH, then convert: 1 ETH = 100 contracts, 0.5 ETH = 50 contracts. The smallest order, 0.1 contracts, is 0.001 ETH.
4. Order type. Limit if you care about the price, market if you care about getting filled now. A single market order is capped at 200,000 contracts (2,000 ETH); limit orders at 600,000.
5. TP/SL. Attach them on the order so the exit exists before the trade does.

Worked example with the API numbers at about 4:16 PM ET (last 2,316.03):

• Size: 100 contracts = 1 ETH = 2,316.03 USDT notional
• At 10x: margin = 2,316.03 / 10 = 231.60 USDT
• Funding at the current +0.022% per 8h: 2,316.03 x 0.00022 = about 0.51 USDT per settlement, paid by longs
• 24h range: 2,292.79 to 2,351.58, or 58.79 points, about 2.5% of price. At 10x, a full-range move against you is roughly 25% of that margin.

The same contract-value check matters on other pairs too, since BTC, SOL, XRP and DOGE perps all carry their own contract value. Read it once per symbol before your first order.

Size from the stop, not from a round number of contracts

Pick a risk budget first. Say 25 USDT, a number chosen only for this example. Suppose you go long at the 2,316.03 last price and the idea is wrong if price trades back to the 24h low of 2,292.79.

• Stop distance: 2,316.03 - 2,292.79 = 23.24, about 1.00% of price
• Size that risks 25 USDT: 25 / 23.24 = about 1.0757 ETH
• Round down to whole contracts: 107 contracts = 1.07 ETH
• Actual risk: 1.07 x 23.24 = about 24.87 USDT
• Notional: 1.07 x 2,316.03 = about 2,478.15 USDT; margin at 10x is about 247.82 USDT

A stop that tight is only a worked example. In practice you would put it where the chart says the trade is wrong, then run the same four lines.

Small sizes on this contract

Because 1 contract is 0.01 ETH, the ladder is easy to read at the 2,316.03 price:

• 0.1 contracts (the minimum) = 0.001 ETH = about 2.32 USDT notional
• 25 contracts = 0.25 ETH = about 579.01 USDT notional, margin at 10x about 57.90 USDT
• 100 contracts = 1 ETH = 2,316.03 USDT notional

What leverage does to the day's range

The 24h range was about 2.5% of price. Against that, the rough buffer to liquidation is 1/leverage:

• 10x: 10% buffer, so a full-range move uses about a quarter of it
• 20x: 5% buffer, so the same move uses about half
• 50x: 2% buffer, smaller than the day's range
• 150x: about 0.67%, which one ordinary candle can cross

Maintenance margin and fees make each real buffer a little smaller than shown.

Common mistakes

• Typing ETH where the box wants contracts, which is the whole point of this post.
• Treating the 150x ceiling as a recommendation.
• Skipping TP and SL on the ticket and planning to add them after the fill.
• Using a market order for size when a limit would do. A single market order can be up to 200,000 contracts, but that does not mean you should send anything near it.

Quick FAQ Q: Can I change leverage after opening? A: Check the position panel for what your account allows; do it before you size, not mid-trade. Q: Why do I see decimals in contracts? A: The lot step is 0.1, so sizes move in tenths of a contract, each 0.001 ETH.

Checklist before you press Buy/Long: margin mode set, leverage set on purpose, size converted to contracts, order type chosen, TP and SL attached.