How the Pengő Became the Forint: Hungary's Currency Reform of 1 August 1946
On 31 July 1946 Hungary withdrew the pengő and the adópengő. On 1 August 1946 it introduced the forint at a rate of 400 octillion pengő to one, retiring twenty-nine zeros in a single step and ending the most extreme hyperinflation ever documented. The forint is still Hungary's currency today.
Last updated: July 2026
Hungary replaced the pengő with the forint on 1 August 1946 at a conversion rate of 4 × 1029 pengő to one forint, the largest currency conversion ratio in monetary history. The reform worked immediately and permanently: the forint held its value from the first week and remains in circulation eighty years later. This page covers the final month of the pengő at week and day resolution, what the conversion rates actually were, why the stabilization succeeded where the adópengő experiment had failed, and what the last pengő notes are today.
The final month of the pengő, week by week
Between 1 July and 1 August 1946 Hungary issued five new banknote denominations, made a parallel currency legal tender, printed its two largest notes ever, and then retired the entire currency. The compression is the story.
| Date | What happened |
|---|---|
| 1 January 1946 | The adópengő is introduced as an inflation-indexed accounting unit. One adópengő equals one pengő. |
| 13 May 1946 | The 1,000,000,000 pengő note is issued, the last note denominated in plain pengő. |
| 25 to 28 May 1946 | The first adópengő tax bills are printed; Finance Minister Ferenc Gordon begins issuing them on 29 May. |
| 27 May to 27 June 1946 | The milpengő series runs its full course, from 10,000 milpengő (1010 pengő) to 1,000,000,000 milpengő (1015 pengő), six denominations in thirty-one days. |
| 1 July 1946 | The b.-pengő series opens at 10,000 b.-pengő (1016 pengő). One adópengő is now worth on the order of 109 pengő. |
| 2 July 1946 | 100,000 b.-pengő issued (1017 pengő). |
| 8 July 1946 | 10,000,000 b.-pengő issued (1019 pengő). |
| 8 to 9 July 1946 | Adópengő tax bills become legal tender (sources differ by one day). |
| 11 July 1946 | The Hungarian National Bank issues the 100,000,000 b.-pengő note (1020 pengő), the highest face value ever put into circulation, and the last pengő banknote ever released. |
| 18 July 1946 | The 10,000,000 adópengő note is printed. |
| 25 July 1946 | The 100,000,000 adópengő note is printed, the last banknote Hungary produces before the reform. |
| 31 July 1946 | The pengő and the adópengő are withdrawn. |
| 1 August 1946 | The forint is introduced at 4 × 1029 pengő to one forint. The hyperinflation ends. |
| 30 September 1946 | Adópengő tax bills finally lapse. |
Sources for this timeline are listed at the foot of the series catalog. Where a date is documented to the day, it is given to the day; where only the month is established, the table says so rather than inventing precision.
The conversion rates
The pengő converted to the forint at 4 × 1029 to one. The adópengő, which had been indexed against inflation since January, converted at 2 × 108 to one, a difference of twenty-one orders of magnitude between the two currencies Hungary had been running side by side.
Set the two ratios beside each other and the adópengő's seven-month record becomes measurable. It was created to hold its value against the pengő and it did precisely that, ending the period worth twenty-one orders of magnitude more than the currency it shadowed. What it could not do was hold purchasing power, because a unit indexed to a collapsing currency tracks the collapse rather than escaping it. The adópengő guide covers that mechanism in detail.
Why the forint held when everything before it had failed
The forint succeeded because the reform changed the underlying fiscal position rather than only the units on the notes. Hungary had already tried renaming the problem twice, with the milpengő and b.-pengő notations and then with the adópengő, and neither slowed the collapse.
That contrast is the durable lesson of 1946 and the reason economists still study the episode. Adding named multipliers to a currency is a printing convenience; it changes how a number fits on a piece of paper and nothing else. Indexing a parallel unit to inflation is more sophisticated, and it protected the specific thing it was designed to protect, government tax revenue, but it left the money supply untouched. The August reform was different in kind: a new currency introduced alongside the fiscal and monetary changes needed to stop the issuance that had driven the spiral. Prices stabilised almost immediately, and the forint has been Hungary's currency continuously since, through the communist period, the 1989 transition and European Union accession.
Hungary's collapse remains the most extreme hyperinflation ever documented, with prices roughly doubling about every 15 hours at the July 1946 peak (Hanke-Krus World Hyperinflation Table, Cato Institute). Its stabilization is equally notable, and less often remarked on: the worst hyperinflation in history was ended in a single step, and it never came back.
The last notes Hungary ever issued
Two notes mark the end of the series. The 100,000,000 b.-pengő of 11 July 1946 was the last pengő banknote issued, and the 100,000,000 adópengő printed on 25 July 1946 was the last banknote of any kind produced before the reform.
A third belongs in the same sentence. The 1,000,000,000 b.-pengő note, worth 1021 pengő, was printed but never released, overtaken by the changeover before it could circulate (Hungarian pengő, Wikipedia, citing Linzmayer, The Banknote Book, 2019). It is the highest face value ever printed on a government banknote, and it exists today only because examples reached collectors rather than tills. The distinction between it and the 100 million b.-pengő, which did circulate, is worked through in the highest denomination banknote ever printed.
What the changeover left for collectors
Because the reform retired the currency abruptly rather than gradually, large quantities of pengő and adópengő notes were left in unspent condition, which is why a series from the worst hyperinflation in history remains affordable eighty years later.
Abrupt demonetizations are good for collectors, and 1946 is a clear case. Notes issued in the final weeks had barely any time in circulation before they stopped being money, so crisp uncirculated examples of several b.-pengő denominations survive in quantity. The pattern repeats across hyperinflation collecting: Zimbabwe's Trillion Series and Venezuela's retired bolívar issues reached the market the same way, in sealed unspent bundles, and that is why the most dramatic notes in the field are so often the most accessible. Every hyperinflation ranked sets the crises side by side.
Planet Banknote stocks the Hungarian series across grades, with common milpengő issues from $99 and the record-setting 100,000,000 b.-pengő at $1,145 in PMG 66 EPQ as of July 2026. Prices and availability change with inventory. The full grade ladder is in the series catalog.
Frequently asked questions
When did the pengő become the forint?
On 1 August 1946. The pengő and the adópengő were both withdrawn on 31 July 1946, and the forint was introduced the following day at a conversion rate of 4 × 1029 pengő to one forint. The forint remains Hungary's currency today.
What was the pengő to forint exchange rate?
400 octillion pengő to one forint, that is 4 × 1029 to one, which retired twenty-nine zeros in a single step and is the largest currency conversion ratio in monetary history (Bomberger and Makinen, 1983). The adópengő converted separately at 200 million to one forint.
What was the last Hungarian pengő banknote?
The 100,000,000 b.-pengő note, issued by the Hungarian National Bank on 11 July 1946 and worth 1020 pengő. It is both the last pengő note issued and the highest face value ever put into circulation on any banknote. A larger 1,000,000,000 b.-pengő note was printed but never released.
Why did the forint succeed when the adópengő failed?
Because the August 1946 reform changed the fiscal and monetary position rather than only the units printed on the notes. The milpengő and b.-pengő notations were printing conveniences, and the adópengő indexed a parallel unit to inflation, which protected tax revenue but left the money supply untouched. The forint was introduced alongside the measures needed to stop the issuance driving the spiral, and prices stabilised almost immediately.
How long did Hungary's hyperinflation last?
The acute phase ran from roughly mid-1945 to 31 July 1946, peaking in July 1946 when prices roughly doubled about every 15 hours (Hanke-Krus World Hyperinflation Table, Cato Institute). The escalation in denominations was concentrated in the final ten weeks: Hungary issued twelve new banknote denominations between 27 May and 25 July 1946.
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Hold the end of the pengő: browse the Hungary collection, see every denomination and date in the series catalog, or read the crisis from the beginning in the Hungary hyperinflation guide.