How Is the Funding Rate Actually Calculated?.

Nearly every serious perp venue calculates funding with the same skeleton: Funding Rate = Average Premium Index + clamp(Interest Rate − Average Premium Index, −0.05%, +0.05%). The premium index measures how far the perp is trading from its index price, sampled repeatedly and averaged over the calculation window. The interest rate is a small fixed constant, 0.00125 percent per hour on venues like Hyperliquid and Variational, representing the cost of borrowing dollars versus holding the asset. The clamp limits how much the interest component can adjust the result, which keeps the premium as the primary driver. Both Hyperliquid’s and Variational’s documentation publish this exact structure.

Take the parts one at a time. The premium index is the heart of the formula, and the detail that matters is that it is built from impact prices, not last-trade prices. The venue asks what it would actually cost to execute a defined notional size against the market, the impact bid and impact ask, and measures those against the index. On Variational the impact margin notional is generally 7,500 dollars; the venue then samples this premium every sixty seconds and averages the samples over the window with a recency-weighted scheme, while Hyperliquid samples every five seconds and averages over the hour. Using executable prices rather than prints makes the measurement harder to manipulate with a single small trade, and the averaging means the rate reflects sustained pressure rather than a moment.

The interest component exists to give funding a structurally correct resting level rather than zero, the reason a normal funding rate is slightly positive, roughly 11 percent annualized flowing to shorts at equilibrium. The clamp around it, plus or minus 0.05 percent on most venues, prevents that fixed component from ever dominating the live premium signal. Clamps and the separate question of caps, the hard ceilings on the final rate, get their own treatment in do funding rates have caps and clamps.

Where venues genuinely differ is in four parameters around the shared skeleton: the index they measure against and how it is built, the sampling cadence and weighting, the calculation window, which on Variational varies per market between one and eight hours while Hyperliquid computes an eight-hour rate and pays one eighth of it every hour, and the final cap, 4 percent per hour on Hyperliquid against 2 percent per hour on Variational. Those parameter differences, small as they look, are most of the reason the same asset prints different funding on different venues, the subject of why funding differs across exchanges.

Last mechanical detail, because it changes what you actually pay: the rate is applied to your position’s notional value, and on Hyperliquid that notional is computed using the spot oracle price rather than the venue’s own mark, so the perp’s dislocation cannot inflate the payments it generates. The full payment arithmetic is in is funding charged on margin or notional, and which price plays which role is in mark price versus index price. For the conceptual layer above all this machinery, the pillar is what a funding rate actually is.