diff --git a/README.md b/README.md
index bafeed3837a68b8d70fd0c840e8f6f72df515e37..84af43e578e1ce4a5138c54b9f8aef753d29b927 100644
--- a/README.md
+++ b/README.md
@@ -10,8 +10,6 @@ Exposes a `DateTime` structure that can be initialized and acted upon using vari
 
 Currently handles dates and times based on the [Proleptic Gregorian calendar](https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar) in adherence to [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601).
 
-Does not currently support time zones outside of UTC.
-
 Does not handle leap seconds.
 
 See the `FormatSeq` structure for display information on what to pass as a `fmt` string.
diff --git a/test.zig b/test.zig
index 8d89c076b87f29d9564e0b2768eddbfc612a843c..c538038388dd84171259003a232bb63078d9d0cb 100644
--- a/test.zig
+++ b/test.zig
@@ -120,7 +120,6 @@ comptime {
         .{ "SS", "78" },
         .{ "SSS", "789" },
 
-        .{ "z", "UTC" },
         .{ "Z", "+00:00" },
         .{ "ZZ", "+0000" },
 
@@ -155,7 +154,24 @@ comptime {
 // https://github.com/nektro/zig-time/issues/9
 test {
     var t = time.DateTime.initUnix(1330502962);
-    try expectFmt(t, "YYYY-MM-DD hh:mm:ss A z", "2012-02-29 08:09:22 AM UTC");
+    try expectFmt(t, "YYYY-MM-DD hh:mm:ss A", "2012-02-29 08:09:22 AM");
     t = t.addYears(1);
-    try expectFmt(t, "YYYY-MM-DD hh:mm:ss A z", "2013-03-01 08:09:22 AM UTC");
+    try expectFmt(t, "YYYY-MM-DD hh:mm:ss A", "2013-03-01 08:09:22 AM");
+}
+
+test {
+    var t = time.DateTime.initUnix(1330502962);
+    try expectFmt(t, "Z", "+00:00");
+    t.z_offset += 31;
+    try expectFmt(t, "Z", "+07:45");
+    t.z_offset -= 65;
+    try expectFmt(t, "Z", "-08:30");
+}
+test {
+    var t1 = time.DateTime.init(2026, 7, 10, 11, 14, 45, 0);
+    t1.z_offset -= 28;
+    try expectFmt(t1, "Z", "-07:00");
+    var t2 = time.DateTime.init(2026, 7, 10, 18, 14, 45, 0);
+    try expectFmt(t2, "Z", "+00:00");
+    try expect(t1.toUnix()).toEqual(t2.toUnix());
 }
diff --git a/time.zig b/time.zig
index 09ce9ec4b006acf7a6f3ee06584809a8765ad5ac..a080f8db9aa656d96b09e5360149dae28473a612 100644
--- a/time.zig
+++ b/time.zig
@@ -19,7 +19,7 @@ pub const DateTime = struct {
     days: u8,
     months: u8,
     years: u16,
-    timezone: TimeZone,
+    z_offset: i8,
 
     pub fn initUnixMs(unix: u64) DateTime {
         return epoch_unix.addMs(unix);
@@ -53,7 +53,7 @@ pub const DateTime = struct {
         .days = 0,
         .months = 0,
         .years = 1970,
-        .timezone = .UTC,
+        .z_offset = 0,
     };
 
     pub fn toISOString(self: DateTime) [20]u8 {
@@ -220,8 +220,7 @@ pub const DateTime = struct {
     }
 
     pub fn toUnix(self: DateTime) u64 {
-        const x = self.toUnixMilli();
-        return x / 1000;
+        return self.toUnixMilli() / 1000;
     }
 
     pub fn toUnixMilli(self: DateTime) u64 {
@@ -231,6 +230,7 @@ pub const DateTime = struct {
         res += @as(u64, self.minutes) * ms_per_min;
         res += @as(u64, self.hours) * ms_per_hour;
         res += self.daysSinceEpoch() * ms_per_day;
+        res = extras.safeAdd(res, @as(i32, -self.z_offset) * 15 * ms_per_min);
         return res;
     }
 
@@ -249,6 +249,19 @@ pub const DateTime = struct {
         return res;
     }
 
+    /// the timezone offset is stored as a signed amount of 15-min increments.
+    /// the structure of the return value is .{ sign, hrs, mins }.
+    /// 'sign' will be either '+' or '-'
+    pub fn tz_parts(self: DateTime) [3]u8 {
+        const o = self.z_offset;
+        const a = @abs(o);
+        return .{
+            if (o < 0) '-' else '+',
+            a / 4,
+            (a % 4) * 15,
+        };
+    }
+
     /// fmt is based on https://momentjs.com/docs/#/displaying/format/
     pub fn formatFmt(self: DateTime, comptime fmt: string, writer: anytype) !void {
         if (fmt.len == 0) @compileError("DateTime: format string can't be empty");
@@ -325,9 +338,8 @@ pub const DateTime = struct {
                     .SS => try writer.print("{:0>2}", .{self.ms / 10}),
                     .SSS => try writer.print("{:0>3}", .{self.ms}),
 
-                    .z => try writer.writeAll(@tagName(self.timezone)),
-                    .Z => try writer.writeAll("+00:00"),
-                    .ZZ => try writer.writeAll("+0000"),
+                    .Z => try writer.print("{c}{:0>2}:{:0>2}", toTuple(self.tz_parts())),
+                    .ZZ => try writer.print("{c}{:0>2}{:0>2}", toTuple(self.tz_parts())),
 
                     .x => try writer.print("{}", .{self.toUnixMilli()}),
                     .X => try writer.print("{}", .{self.toUnix()}),
@@ -358,7 +370,6 @@ pub const DateTime = struct {
     pub fn formatAlloc(self: DateTime, alloc: std.mem.Allocator, comptime fmt: string) !string {
         var list = std.Io.Writer.Allocating.init(alloc);
         defer list.deinit();
-
         try self.formatFmt(fmt, &list.writer);
         return list.toOwnedSlice();
     }
@@ -408,7 +419,6 @@ pub const DateTime = struct {
         S, // 0 1 ... 8 9 (second fraction)
         SS, // 00 01 ... 98 99
         SSS, // 000 001 ... 998 999
-        z, // EST CST ... MST PST
         Z, // -07:00 -06:00 ... +06:00 +07:00
         ZZ, // -0700 -0600 ... +0600 +0700
         x, // unix milli
@@ -530,6 +540,12 @@ fn wrap(val: u16, at: u16) u16 {
     return if (tmp == 0) at else tmp;
 }
 
+fn toTuple(array: anytype) @Tuple(&@as([array.len]type, @splat(std.meta.Child(@TypeOf(array))))) {
+    var result: @Tuple(&@as([array.len]type, @splat(std.meta.Child(@TypeOf(array))))) = undefined;
+    inline for (array, 0..) |v, i| result[i] = v;
+    return result;
+}
+
 pub const Duration = struct {
     ms: u64,
 };