The Crypto Times Indonesia USDT Premium Index · daily fix 11:30–12:30 WIB · CTPI-USDT-SPOT-IDR

Methodology v0.1.0 · DRAFT pending calibration and Owner sign-off. Values marked TO BE SET are filled from calibrate.py after roughly 44 hours of live capture; the version number does not change when they are filled, because filling them does not change how a fix is computed.

What is measured

The Crypto Times Indonesia USDT Premium Index (CTPI-USDT-SPOT-IDR) measures how much more (or less) a dollar stablecoin costs in Indonesian rupiah on Indonesian exchange order books than the global dollar price converted at the reference exchange rate, every trading day. Two numbers are published: the raw premium (rupiah price of USDT versus USD/IDR) and the peg-adjusted premium (the headline), which also divides out USDT’s own small deviation from $1 so that only the Indonesia-versus-world gap remains.

What to expect. No level is presumed. Indonesians reach a digital dollar through rupiah bank and e-wallet on-ramps into a small set of OJK-supervised exchanges; fees, on-ramp friction, retail demand and venue depth can hold the rupiah price of USDT away from the world price in either direction. The archive records the size and persistence of that gap; the page does not dress a quiet reading up as a story.

The daily fix

Fix window 11:30–12:30 WIB (12:00 ± 30 minutes), published at 12:31 WIB (05:31 UTC) by a systemd timer with Persistent=true; if the host is off through the window, the timer runs on boot, finds no samples and refuses to publish. No estimate is ever published in place of a missed fix; a missed or late fix is recorded in the corrections log as a publication-timing entry.

The ECB publishes its daily reference rates around 16:00 CET, which is 21:00–22:00 in Jakarta, nine hours after the window closes; the fix therefore always prices against the prior ECB business day’s rate, the family’s deterministic rule, and its date is cited with every fix.

Official fixes are computed every Monday to Friday (WIB). Local public holidays do not pause the index: crypto trades every day, so a Indonesian public holiday is an ordinary fix day, priced against the ECB reference rate by the usual rule below. Weekend runs store an indicative point at the same fix time, measured against the last business day’s USD/IDR and marked distinctly on the chart.

Inputs

• Venue quotes: the USDT/IDR order book of each constituent exchange, sampled every 60 seconds during Indonesian market hours (08:00–23:59 WIB) and every 300 seconds overnight. Each sample’s raw payload is stored verbatim and never modified.
• USDT/USD reference: Kraken spot USDT/USD best-bid/best-ask mid, sampled on every collector pass, seconds before the venue books.
• USD/IDR reference: the ECB euro foreign exchange reference rate cross (EUR/IDR ÷ EUR/USD), published under a permissive licence on TARGET business days. The prior business day’s rate applies; it may be carried across weekends and holidays for at most 5 calendar days, beyond which an official fix refuses.

Why the family pairs every sample with its own reference

The engine that computes this index also computes The Crypto Times India Bitcoin Premium Index, where the global leg moves inside the window; the family rule pairs each venue sample with the reference captured nearest to it in time (within 120 seconds; unpaired samples are counted and dropped, never estimated). For a stablecoin leg the pairing changes nothing materially, but one rule for the whole family is worth more than two.

Computation

1. For each paired sample: r = venue_mid_idr ÷ usdtusd_ref — the USD/IDR rate implied by that venue’s USDT quote.
2. Per venue: the median of r across its paired samples is the venue observation; the median two-sided rupiah depth resting within ±TO BE SET bps of mid (stored bands: 50, 100) is the venue weight.
3. Eligibility: a venue is excluded if it is shadow-listed, has fewer than 2 paired samples in the window, has zero in-band depth, or its depth is below the floor of Rp TO BE SET two-sided. Exclusions are recorded in the fix’s provenance with the venue’s would-be value.
4. Aggregate: the depth-weighted median of the venue observations, R. A venue must supply real resting depth, not just a printed price, to move the fix.
5. Peg-adjusted premium (headline): premium_pct = (R ÷ USDIDR − 1) × 100.
6. Raw premium: raw_premium_pct = (observed_mid_median ÷ USDIDR − 1) × 100.
7. Published price level: value = R × usdtusd_ref (rupiah per USDT), where usdtusd_ref is the median of the references actually paired, so that value ÷ (usdtusd_ref × USDIDR) − 1 reproduces the headline premium exactly from the figures on the page.

Publication gates

An official fix requires at least TO BE SET eligible venues, a publishable USD/IDR reference within the carry ceiling, at least one paired USDT/USD reference, and no existing official fix for that time. Officials are immutable once written; restatements go only through governance tooling and appear in the corrections log.

Quality flags (published with the fix, never hidden)

two_venue_aggregate; high_venue_dispersion when venue observations differ by more than TO BE SET bps; unpaired_samples(n); insufficient_venues on indicative fixes only.

Constituents and venue disclosure

Candidate venues at launch: Indodax, Tokocrypto and Luno (Luno’s rupiah book confirmed on 23 September 2026), with Pintu and Reku onboarded from configuration once a public rupiah order book is confirmed for each. Since January 2025 Indonesia’s crypto exchanges are supervised by the Financial Services Authority (OJK); a venue’s regulatory or security history is disclosed beside the fix, never assumed away. Tokocrypto runs on Binance’s cloud platform; only a rupiah book served by Tokocrypto itself is used, never a Binance-hosted book. Constituent status is set from measured order-book depth during calibration and reviewed against the family venue policy; the venue-status line and the per-exchange table state, every day, which venues the number includes and why any is excluded. Changes appear in the changelog.

Live indicative readings

Between fixes the page shows a 5-minute indicative reading computed with the same pairing and aggregation, against the USD/IDR rate in force at the sample. Past 15 minutes without a usable sample the live block shows STALE rather than a stale number. Indicative readings are never part of the daily fix series.

The family’s synchronized reading

Besides the daily fix, the engine records one reading a day at 12:00 UTC — the same moment for every index in the family (19:00 WIB here) — computed exactly as above over 11:55–12:05 UTC (18:55–19:05 WIB), against the latest ECB reference captured before the window closes, which is always the prior business day’s rate. It exists so that a future multi-country composite can combine markets observed at the same instant rather than hours apart. It is not this index’s official value and is never part of its fix series; a day on which it cannot be computed is recorded as INVALID with its reason. Around that window the collector samples every 60 seconds whatever the local hour. The series is published at /v1/sync on the engine host.

Versioning

The methodology version changes only when the way a fix is computed changes — never for display, documentation or the filling of calibration values above. Package versions are separate.

2026-09-24 · engine v1.12.3 · methodology v0.1.0 (draft)

Methodology text: Local public holidays do not pause the index: a holiday is an ordinary fix day, priced against the ECB reference rate by the usual rule; weekends stay indicative. No change to how the fix is computed. Official fixes remain switched off.

2026-09-24 · engine v1.12.1 · methodology v0.1.0 (draft)

Venue discovery (run 23 September 2026): Indodax, Tokocrypto (a rupiah book, as required) and the Kraken and ECB references answered as documented, and Luno’s rupiah book was confirmed, so Luno is enabled as a third candidate. Official fixes remain switched off.

2026-09-23 · engine v1.8.0 · methodology v0.1.0 (draft)

Index created on the CTPI family engine, configured for USDT/IDR: Indonesian venues Indodax and Tokocrypto enabled; Luno, Pintu and Reku shipped as configuration-only candidates pending confirmation of a public rupiah order book; USDT/USD reference from Kraken paired per sample; ECB USD/IDR denominator; noon-WIB fix published 12:31 WIB; raw and peg-adjusted premiums; the family’s synchronized reading recorded daily at 12:00 UTC (19:00 WIB). Official fixes remain switched off ([fix].official_enabled = false) until calibration values are set from live data and the methodology is signed; the daily timer stores indicative (shadow) fixes meanwhile.

No corrections, restatements or publication-timing entries yet. Entries are added here, inside this document, never on a separate page: a missed or late fix is recorded as a publication-timing entry; a change to a published value is a restatement, with the old value, the new value, the reason and the date.

Date	Type	Fix date	Detail
none recorded

The daily fix series to date. Full series JSON with a stable schema: /v1/fixes.json.
CSV JSON

How much more (or less) one USDT costs in rupiah on Indonesian exchanges than the world dollar price converted at the ECB-derived USD/IDR rate, in percent, at the daily fix. Positive means buyers in Indonesia pay more than the world price; negative means less.

Rupiah reaches a digital dollar through bank and e-wallet on-ramps into a small set of supervised exchanges, while USDT and dollars move freely elsewhere. Fees, transfer friction, retail demand and the depth of each venue’s book can hold the rupiah price of USDT above or below the world price. The archive records how large that gap is and how long it lasts; it does not presume a sign or a level.

Peg-adjusted. The raw premium compares the rupiah price of USDT with USD/IDR; the peg-adjusted premium also divides out USDT’s own small deviation from $1, so only the Indonesia-versus-world gap remains. Both are published every day.

No. It is a measurement of one gap, once a day, from public order books. It says nothing about where the rupiah or USDT will trade tomorrow, and it recommends no trade and no exchange.

Candidate constituents are Indodax, Tokocrypto and Luno (its rupiah book was confirmed on 23 September 2026), with Pintu and Reku added once a public rupiah order book is confirmed for each. Since January 2025 Indonesia’s crypto exchanges are supervised by the Financial Services Authority (OJK). Tokocrypto runs on Binance’s cloud platform; only its own rupiah book counts. Constituent status is set from measured order-book depth during calibration and reviewed against the published venue policy; the venue-status line and the per-exchange table state, every day, which venues the number includes and why any is excluded — including a venue’s regulatory or security history.

No. These are public, on-exchange order-book prices on Indonesian venues open to KYC-verified users. The premium is a market measurement, not a rupiah exchange rate, and the reference rate is the ECB cross, not Bank Indonesia’s.

Crypto trades every day. Official fixes run Monday to Friday, and local public holidays do not pause the index: a holiday is an ordinary fix day, priced against the ECB reference rate by the usual rule. The ECB reference does not update at weekends, so weekend readings are published as indicative, measured against the last business day’s USD/IDR, and marked distinctly on the chart.

The per-exchange table shows sampled order-book best bid and ask — tradeable quotes at sample time, subject to depth and fees. The index value itself is a computed benchmark, not a quote.

The citable number is the once-daily fix. A live indicative reading updates continuously above it and is never part of the daily fix series.