I hope this isn't a dumb question...

Is there a "universal" currency to use in Sweden, Norway, and Denmark?

I know Sweden has the SEK, Denmark has the DKK, and Norway has the NOK. But are any of these acceptable in all 3? Or the Euro?

Maybe I'm just being lazy but it would be nice to convert once and be done.

No they are all separate currencies, all with a different exchange rate.

Meant to add - just get money from an ATM in each country and try and spend it all before you leave.

No, of course not. A country's currency is just that, nothing "universal" about it. You might find someone, somewhere, willing to accept something other than the country's currency, but obviously it would be at their trouble and expense.

No, in fact, in Stockholm we were given flak when a ticket vendor saw that we had a Norweigan coin among our change..even though we weren't giving to him.

Most places we visited in Switzerland (in several towns and cities) gladly accepted Euros even tho they have the Swiss Franc.

In all our travels that's really the only experience we have in countries with non-Euro currency.

I understand that the euro is quite widely accepted in Northern Ireland, because it is the currency of the Republic of Ireland and many people shop in the north because it is often cheaper.

I have also signs in Fishguard, west Wales, stating that euros were accepted. The ferry from Ireland arrives there.

Some shops in Norway will accept euros, probably true in Denmark too, but at a terrible exchange rate. Stick to the local currency.

If you traveled in Switzerland, you should have no sticker shock with prices even in Norway.

...convert once and be done..

I would assume (hope) you are not converting anything.

As mentioned above, just go to ATM in each country and take what you need out. No need to bring any currency to convert.

Markaphx, you may have been able to spend your Euro in Switzerland but what was the exchange rate? It really should be accepted that apart from the Eurozone European countries have their own currency and some may consider it insulting to be offered payment in another currency.

I'm not saying that locals will be insulted by someone trying to pay with a foreign currency - but you might look pretty silly - and will probably lose a LOT of money on the transaction.

Sweden, Denmark, and Norway have separate currencies and they are not interchangeable. However, you can pay for everything with a debit card or credit card except maybe purchases from street vendors. If you feel you need some cash, get as little as possible from the ATM at the airport. Use a credit card or debit card that doesn't charge interchange rates or fees for ATM transactions.
If you have cash left use it to pay your hotel bill, pay with cash and then pay the difference on your credit card.
Many airports in Europe will have charity boxes for "leftover cash and coins" and the money goes to Unicef or an identified local charity. Some airlines will also "pass the hat" for Unicef.

"it would be nice to convert once and be done."

Which is exactly what will happen. You will be done.

Merchants aren't charities: if they accept foreign currency (and the currency of the country next door is just as foreign as that of Upper Volta) they've got extra costs and risks to carry, and they'll reflect those costs plus (human nature being what it is) whatever else they think they'll make out of you in the rate they charge.

I've had franchisees on major international roads openly boast they made more out of what they ripped off customers tendering foreign currency than from their underlying business.

They all have different currencies. I lived in DK for many summers and the Danes didn't want to get mixed up in the Euro situation, so along with Norway and Sweden, kept their Kroner.

However, in tourists areas in Copenhagen, one can use Euros at some stores. Happy Travels!