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Free calculator · US substantial presence
Substantial presence test calculator (183-day formula)
Last year's US trips still count this year. Add your dates across three calendar years and see exactly how close the formula brings you to 183.
The rule: days this year + ⅓ of last year’s days + ⅙ of the year before’s. The test is met at 183 or more, with at least 31 days this year.
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How the count works
Last year still has a say. Your current-year days count fully, the year before counts at one third, and the year before that at one sixth. The threshold is 183 weighted days, with a separate 31-day current-year floor.
Add each US stay once, including entry and exit dates. Pick a future check date to include the part of a planned stay up to that date.
Example: Alex spends 120 days in the US in each of 2024, 2025 and 2026. On 8 Oct 2026, the total is 120 + 40 + 20 = 180 weighted days. Three more US days in 2026 would reach 183; in a new calendar year, the weights change.
Questions
How do I calculate the substantial presence test?
Add your US trips for this year and the two years before it. The formula adds all this year’s days, one third of last year’s and one sixth of the year before. It reaches its threshold at 183 weighted days, with at least 31 US days this year.
Do partial days count?
Yes. Any part of a day counts, including arrival, departure and a same-day visit. Overlapping stays count each date once.
What is the 31-day rule?
You need at least 31 days in the US in the current calendar year for this formula to apply. A large total from earlier years alone does not clear that floor.
Which days don't count?
Some days don't count for some people — students and teachers on F/J/M/Q visas, commuters from Canada or Mexico, under-24-hour transit, a medical condition. This calculator counts every day you enter: leave those stays out yourself.
Is 183 days in one year the same as the test?
No. The test uses three calendar years with different weights. You can reach 183 weighted days with fewer than 183 US days this year.
Is anything I enter saved or sent?
No. The count runs in your browser. This page makes no network request with your dates and stores nothing; closing it clears them.
