The unit: pico-dollars
Every amount in our ledger is calculated and stored as a whole number of pico-dollars —
one pico-dollar is 10−12 USD (one trillionth of a dollar).
For scale, one US cent is ten billion pico-dollars. Working at this resolution means an amount far
smaller than a cent is an exact whole number, never a fraction we have to round away.
Internally the charge path uses 128-bit integers and the database stores integer pico-dollars.
No floating-point arithmetic is ever used to compute a charge or a balance.
Usage charges — exact, with no rounding
Charges that scale with a quantity — tokens, per-seat, and
per-instance fees — are computed as an exact integer of pico-dollars:
quantity × the published per-unit rate. There is no division, no truncation, and
no rounding on this path.
A charge of a few millionths of a cent is recorded as exactly that. It is
never floored to $0.00.
Storage rent — one small, published rounding
Storage rent is the one place a rounding legitimately exists, because it is intrinsic rather than a
choice: rent is prorated daily, and a month's day count (28–31) does not divide evenly in any
fixed-point money unit.
Each day's rent is computed in whole pico-dollars. The only rounding is that daily proration, and it
leaves a residual of less than one pico-dollar per day (under ~3×10−11 USD
across a whole month). It is truncation in your favor — never an over-charge —
it follows a single published rule, and it is replayable: we can re-derive every daily
charge from your storage history.
Planned: a monthly true-up that drives this residual to zero, making the monthly storage total
exact to the pico-dollar.
What you see vs. what we bill
Numbers shown in the dashboard and API are rounded to a readable unit. Two rules govern that display,
and neither affects what you are billed:
- A real charge is never shown as $0.00. Display values round half-up with a floor, so a genuine sub-cent charge stays visible.
- The exact pico-dollar value is the source of truth. Every wallet and transaction surface carries the exact amount, and no accounting decision — a debit, a balance check, a spend limit — is ever made on a rounded number.
Cash settlement
The single place internal pico-dollars would convert to the whole cents a payment processor can move
is at cash settlement, and that rule would be stated here.
Today no usage-based cash settlement exists: account top-ups are fixed whole-dollar
amounts credited exactly, and subscription tiers are billed at their flat published price — so there
is currently no usage→cents rounding step in effect at all.
How we keep ourselves honest
The unit is the substrate; the proof is the product. Every billing cycle is independently checked:
- A reconciliation process re-derives every recorded charge from the rate card and the metered quantities, and flags any drift between what was computed and what was recorded.
- An adversarial reconciliation harness drives the full workflow against the live system and verifies that every billable event is charged the exact expected amount — most recently with zero amount-mismatches across a full cycle.
We account in pico-dollars and bill quantity-based usage exactly — a charge smaller than a cent
is never rounded away. Storage carries one small, published, in-your-favor proration of under a
pico-dollar per day (with a monthly true-up to zero planned). We always bill the exact value, not the
rounded one.