What is the correct daily aspirin dosage?

Absolute minimum seem to be 75mg a day. The general recommendation seem to be two of those tablets per day taking the daily amount to 160 mgs a day.

Another thought is to take the 320 mg version every other day.

Some extra strength tablets seem to come in 500mg versions. You may want to avoid those for daily dosages.

The following may be a good candidate for daily usage

Bayer Regimen Tablets, Adult Low Strength Aspirin Pain Reliever, 81 mg

The 80 mg version is also often called Baby Aspirin

References

Pros and cons article from FDA

wikipedia reference