Work out debt to gdp ratio instantly with clear inputs, formula shown and shareable results.
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.
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
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.
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.
Because it determines whether debt compounds faster or slower than the economy. A negative differential means a country can grow out of its debt.