Z-spread, I-spread & G-spread calculator

In short

One bond, three spread measures.

Interactive: Z-spread, I-spread & G-spreadHard

One bond, three spread measures side by side. The reference curve is flat here (one swap rate, one government yield) — enough to see how the measures relate; real desks feed in the whole curve.

Bond clean price Coupon % Years to maturity Swap rate % Government yield %

Yield to maturity: —
Z-spread (flat curve): —
I-spread: —
G-spread: —

With a flat curve, Z and I nearly coincide — the daylight between them in real markets is curve shape. Feed the same bond into the CDS–bond basis tool to complete the picture: bond spread vs. derivative spread.

The idea behind it

This calculator belongs to Spread Measures, where the mechanism it computes is explained step by step, with the formula, what each input means and where the simple model stops being right. Everything is computed in your browser; nothing you type is sent anywhere.

All calculators

Not advice. This explains how something works; it is not a recommendation, and nothing here is tailored to you. You can lose everything you put in — with leveraged instruments, considerably more. StrikeAndYield is not a regulated firm and provides no financial services.

The same in full — six points, and why each one matters

No advice, no recommendation. Nothing on this page constitutes investment, financial, legal, tax or accounting advice, a personal recommendation, or an offer or solicitation to buy or sell any financial instrument.
Nothing here is tailored to you. This is written for a general audience. It does not consider your objectives, financial situation, knowledge, time horizon or tolerance for loss.
The examples are simplified. Worked examples use round numbers and leave out costs, spreads, taxes, collateral, settlement and market conventions that materially change real outcomes.
The models are teaching models. Formulas shown are standard textbook formulations. Institutions add calibration, live market data and credit, funding and capital adjustments — nothing here will reproduce a dealer’s quote or produce a valuation you can rely on.
These instruments carry risk. You can lose your entire investment. Leveraged instruments — futures, options, CFDs, perpetual futures and similar — can cost you considerably more than you originally deposited.
We are not a regulated firm. StrikeAndYield is an independent publication by DELISORIA. It is not a bank, broker, fund manager or licensed adviser, it provides no financial services, and reading it creates no client relationship. For decisions about your own money, consult a professional licensed in your jurisdiction. See the full disclaimer.