Perpetual Contracts and Funding Rates
Perps never expire: the funding rate is the small recurring payment that keeps them glued to spot.
That's 9 funding payments over 3 days. It looks tiny against the position, but against the $50.00 margin you actually posted it's 9.0% — that's the number that eats your account. Always fold it into your break-even.
Play with the widget above first. Set a position size, pick a funding rate and leverage, and set the number of days you hold. Watch how a "tiny" fee quietly eats your margin. That single feeling is the whole module.
A perp never expires
A perpetual contract (a "perp") is a futures bet with no settlement date. A normal futures contract dies on a fixed day and force-settles to the spot price. A perp just keeps running. You can hold a 100x long for five minutes or five weeks. Nobody closes it for you.
That freedom creates a problem. If a contract never has to settle back to reality, what stops its price from drifting far away from the real coin price on the spot market?
The funding rate is the leash
The answer is the funding rate: a small payment that traders on one side of the market send to traders on the other side, every few hours (commonly every 8 hours).
It is not a fee the exchange keeps. It is a peer-to-peer transfer between longs and shorts, and its whole job is to pull the perp price back toward spot. When the perp trades above spot, longs pay, so being long gets more expensive and some longs close, dragging the price down. When the perp trades below spot, shorts pay, and the same pressure pushes the price back up. That constant tug is what keeps a never-expiring contract glued to the real market.
Who pays whom
Two cases, and this is the part to memorize:
- Positive funding → longs pay shorts. This happens when the crowd is leaning long and the perp sits above spot. If you are long, money leaves your account each interval. If you are short, you get paid.
- Negative funding → shorts pay longs. The crowd is leaning short, the perp sits below spot. Now shorts pay, and longs collect.
So the sign tells you which side is crowded, and holding the crowded side costs you money over time.
It is a real cost, not a footnote
Here is the trap. Funding is charged on your position size (the full notional value you control), not on the margin (the smaller cash you actually put up). On high leverage those two numbers are miles apart, so a rate that looks like a rounding error becomes a serious drain.
A funding rate of 0.01% every 8 hours sounds like nothing. But it lands three times a day, every day you hold, on your whole position. Combine that with 100x leverage and it can quietly burn a chunk of your margin before the price has moved a single dollar.
The survival rule: funding is a clock running against you. A perp is built for quick, high-conviction moves. The longer you sit on the crowded side, the more the leash costs you. Before you hold overnight, check the funding rate and ask "how many payments will I owe, and can my margin survive them?"
The funding formula and the 8-hour clock
Most venues compute funding from two parts:
Funding Rate = Premium Index + clamp( Interest Rate − Premium Index, −0.05%, +0.05% )
- Premium Index: how far the perp price sits above or below spot right now. This is the dominant term and the thing that flips funding positive or negative.
- Interest Rate: a small fixed baseline, commonly 0.01% per 8-hour interval (about 0.03% per day). It reflects the cost difference between the quote and base asset.
- clamp(…, ±0.05%): bounds the interest-vs-premium adjustment so a single interval's rate stays sane.
| Term | Typical value (per 8h) | Role |
|---|---|---|
| Interest rate | 0.01% | fixed baseline |
| Premium index | varies (can be ±) | tracks perp vs spot gap |
| Resulting funding | often ~0.01%, spikes higher | what you pay/receive |
Interval: funding usually settles every 8 hours (00:00, 08:00, 16:00 UTC on many venues), three payments a day. You only pay or receive if you are holding a position at the exact settlement timestamp. Open after it and close before the next one, and you pay nothing.
Payment = Position Notional × Funding Rate. Note: notional, not margin.
Reading funding as a sentiment gauge
Because the sign of funding shows which side is crowded, traders read it as a fear/greed meter:
- High positive funding: longs are stacked and paying a premium to stay long. The market is greedy and possibly over-extended. Crowded longs are fuel for a long squeeze (a sharp drop that liquidates them).
- Deeply negative funding: shorts are crowded and paying. Fear is high; the setup for a short squeeze (a sharp rally) is building.
- Funding near zero: balanced, no strong lean.
This is a context signal, not a trade trigger. Extreme funding tells you the crowd is lopsided and a violent unwind is possible. It does not tell you the exact moment. Some traders also run "funding carry": deliberately take the paid side (e.g. go short-perp / long-spot when funding is very positive) to collect the payment while staying market-neutral.
Worked example: the cost of holding a 100x perp
You open a long worth $10,000 notional at 100x leverage. That means your margin is only $100.
Funding is +0.01% per 8h (positive → you, the long, pay).
- Per interval: 0.01% × $10,000 = $1
- Per day (3 intervals): $3
- Per week (21 intervals): $21
Now compare to what you actually risked:
| Held for | Funding paid | As % of your $100 margin |
|---|---|---|
| 1 day | $3 | 3% |
| 3 days | $9 | 9% |
| 7 days | $21 | 21% |
You have lost 21% of your margin in a week and the price has not moved at all. If funding spikes to a hot-market 0.05% per 8h, that same week costs $105, more than your entire margin. The position gets bled to liquidation by funding alone.
Takeaway: on high leverage, always convert funding into "% of my margin per day," not "% of position." The small number is lying to you.
Quick knowledge check
1. Funding is positive. Are you paying or receiving as a long? Paying: positive funding means longs pay shorts.
2. Is funding charged on your margin or your full position size? Your full position (notional), which is why it hurts so much at high leverage.
3. What is funding actually for? To keep the never-expiring perp price anchored to the spot price by paying the crowded side to thin out.
Sources
- He, Manela, Ross & von Wachter, "Fundamentals of Perpetual Futures" (academic), on the funding-rate mechanism that tethers perpetuals to spot.
- BIS Working Paper 1087 (Schmeling, Schrimpf & Todorov), "Crypto carry" (the original perpetual swap funding mechanism).
- CFTC, "Policy Statement Concerning the Listing of Perpetual Contracts."
- Kim & Park, "Designing Funding Rates for Perpetual Futures in Cryptocurrency Markets" (arXiv:2506.08573).