What are my chances as an international student to get into the University of Washington?

I took IB MYP courses my freshman and sophomore years and the full IB diploma in my junior and senior year.

My school does not report GPA nor rank, but I approximate my GPA to be around a 3.4-5 unweighted, my grades trend go up and down because I chose to take the full IB Diploma.

SAT: 1290 (super scored)

ECs:
President of Chess Club
Model United Nations (Chair and Delegate)
Won numerous awards: Best Delegate at Harvard Model Congress Asia, and best delegate at 2 more regional conferences as well as chaired a committee myself once.
Captain of Varsity Softball (won MVP)
Varsity Badminton (Won bronze and gold before, as well as most improved player award)
Junior ROTC - served for 3 years

Community Service:
School Build Project - raised over $150k with my peers and built a school in rural areas
Head volunteer at annual fair to raise money for charity (4 years in a row)

Work Experience:
Interned at the Ministry of Commerce over the summer (120 hours)

For me, my grades are my biggest concern as my trend does not look so well, what are my chances of getting in?

I’m applying for Pre-Social Sciences (not direct to any major)

The holistic approach to admissions at UW may favor you. Your SAT and GPA are on the lower side for an international applicant but not disqualifying, and IB rigor may help your cause. Your ECs and service/work experience are great!

Here is some information to help you assess your chances:

According to the Common Data Set, these factors are “very important” in the UW’s admission decisions:

Academic GPA
Application essay
Rigor of secondary school record

These factors are “important”:

Extracurricular activities
First generation college student
Standardized test scores
Talent/ability
Volunteer work
Work experience

These factors are “considered”:

Character/personal qualities
State residency

The 2017-2018 Common Data Set reports the middle 50% ACT range of enrolled freshmen was 27-32.

The 2018-2019 Common Data Set has not been published, but according to a Seattle Times article a few months ago, the 2018 enrolled freshmen (vs. 2017) averages were as follows:

Unweighted GPA: 3.8 (3.79)
SAT Math: 685 (657)
SAT Reading and Writing: 644 (629)
ACT Composite: 29 (28)

Even though your GPA is not at the higher end, you are taking a rigorous course of study, and your SAT is in range. You have demonstrated leadership ability and achieved success in a variety of areas, especially in service to others. This seems to be a particular emphasis at Washington. Your application essay will be very important. I like your chances! Good luck!