Blended APR — how loan cost is averaged across positions
A cost-weighted realized APR across all your DeFi debt positions, weighted by both principal size and how long it was held.
What is Blended APR?
Blended APR is a single interest rate that summarises the cost of all your DeFi debt positions over the selected time window (7d, 30d, 90d, or 1y). It is not a simple arithmetic average of each position's APR — it is weighted so that larger and longer-held debts dominate the result.
Realized, not quoted
The number is derived from the actual growth of your debt between daily snapshots — not from the rate the protocol advertises. If a protocol shows a 5.00% borrow APR but your debt actually grew at an effective 4.73% over the period (because the rate fluctuated, or because some days were partial), the Blended APR uses 4.73%. This makes it an honest measure of what you really paid.
How it's calculated (formula)
For the selected window, the system aggregates two numbers across every position: • total cost (USD) — interest accrued, summed across every snapshot gap • principal × days (USD-days) — the debt balance multiplied by how long it was held, integrated over the window The blended rate is then: Blended APR = (Σ costUsd) × 365 / Σ (debtUsd × days) Multiplying by 365 annualises the rate so it is comparable to a quoted APR. If a position only existed for half the window, only that half contributes to its USD-days.
Worked example
Suppose you have two debt positions held for the full 30-day window: • Position A: $16,500 debt, $2.70 of interest accrued • Position B: $960 debt, $0.09 of interest accrued Each position's realized APR is: APR(A) = $2.70 × 365 / ($16,500 × 30) = 4.73% APR(B) = $0.09 × 365 / ($960 × 30) = 2.83% The blended rate uses the totals: total cost = $2.79 total USD-days = $16,500 × 30 + $960 × 30 = 524,300 Blended APR = $2.79 × 365 / 524,300 = 4.63% The result sits very close to A's APR because A carries roughly 96.6% of the principal·time exposure.
Why principal × time, not just principal
Weighting by principal alone would overstate a small position that was opened recently, and understate a large one that was repaid mid-window. Using principal × days makes a $10k debt held for 30 days count the same as a $20k debt held for 15 days — both represent the same exposure to interest. The Share column in the per-position table is computed from this same principal·days quantity, which is why it can differ from the share of current debt.
How the per-position APR is computed
Each position in the By position table also shows an individual realized APR, computed with the same formula but restricted to that position: APR(position) = costUsd × 365 / (debtUsd × days) Because the loan cost engine subtracts deposits and repayments from raw debt diffs (so user actions don't masquerade as interest) and substitutes any anomalous days with the position's own realized rate, the APR reflects pure interest accrual rather than balance changes.
Window-scoped — what changes when you switch ranges
Switching between 7d / 30d / 90d / 1y recomputes the blended rate over that window. The number can shift if a position was opened or closed partway through, if borrow rates changed across the period, or if recent days carry unusually high or low cost. A wider window smooths short-term spikes; a narrower window reflects current borrowing conditions more closely.
When does it show '—'?
The blended APR displays a dash when there is not yet enough data to compute a realized rate. This usually means the daily snapshot job has run fewer than two times for your debt positions, or all positions opened today. The first cost data point appears once two snapshots taken at different times exist for the same position.