Debt To GDP Ratio Calculator

Work out debt to gdp ratio instantly with clear inputs, formula shown and shareable results.

About Debt To GDP Ratio Calculator

Debt sustainability turns on the difference between the interest rate and the nominal growth rate. When growth exceeds the interest rate the ratio falls automatically even with a balanced primary budget; when the reverse holds, a primary surplus is needed just to hold the ratio steady.

Formulas

Debt ratio

Ratio % = Public debt / GDP x 100

Debt dynamics

Annual change = (r - g) / (1 + g) x Debt ratio

Stabilising primary balance

Required primary surplus % of GDP = (r - g) / (1 + g) x Debt ratio

Worked example

With the default values below, Debt To GDP Ratio Calculator returns Debt to GDP ratio of 83.05%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Public debt outstanding: 245,000,000,000,000
Gross domestic product: 295,000,000,000,000
Nominal GDP growth: 9.5
Average interest rate on debt: 7.2

Results

Debt to GDP ratio: 83.05%
Interest rate minus growth rate: -2.30%
Annual change in ratio from debt dynamics: -1.744%
Primary balance needed to stabilise the ratio: -1.744%

Step by step

1Values used
2Debt ratio
3Debt dynamics
4Stabilising primary balance
5Debt to GDP ratio= 83.05
6Interest rate minus growth rate= -2.30
7Annual change in ratio from debt dynamics= -1.744
8Primary balance needed to stabilise the ratio= -1.744

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Indicative estimate only. Fees, entitlements, limits and formulas vary by jurisdiction, statute, policy wording and the facts of the case. This is not legal, tax, insurance or financial advice — confirm with a qualified professional or the relevant authority.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Indicative estimate only. Fees, entitlements, limits and formulas vary by jurisdiction, statute, policy wording and the facts of the case. This is not legal, tax, insurance or financial advice — confirm with a qualified professional or the relevant authority.

Frequently Asked Questions

Is there a dangerous threshold?

No universal one. Japan sustains well over 200% in its own currency while some emerging economies face crises below 60%. Currency denomination and maturity matter more than the level.

Why does the growth-interest differential matter so much?

Because it determines whether debt compounds faster or slower than the economy. A negative differential means a country can grow out of its debt.