diff --git a/CHANGELOG.md b/CHANGELOG.md
index ed68882d..5cc093cc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 * [#103](https://github.com/dblock/strava-ruby-client/pull/103): Migrate Danger to use the `danger-pr-comment` reusable workflow - [@dblock](https://github.com/dblock), [@Copilot](https://github.com/apps/copilot-swe-agent).
 * [#104](https://github.com/dblock/strava-ruby-client/pull/104): Fixes `Danger Comment` workflow failing with a `contents: none` permissions error - [@dblock](https://github.com/dblock).
 * [#102](https://github.com/dblock/strava-ruby-client/pull/102): Changes default API base URL to `https://www.api-v3.strava.com` and adds `revoke`, deprecating `deauthorize`, per Strava's June 2026/2027 developer program changes - [@dblock](https://github.com/dblock).
+* [#105](https://github.com/dblock/strava-ruby-client/pull/105): Adds `total_elevation_gain`, `total_elevation_loss` and formatted helpers to `Strava::Models::Stream`, computed from altitude stream data - [@dblock](https://github.com/dblock).
 * Your contribution here.
 
 ### 3.0.0 (2025/10/24)
diff --git a/README.md b/README.md
index 4f6b9c62..33ed032c 100644
--- a/README.md
+++ b/README.md
@@ -684,6 +684,17 @@ streams.latlng # => Strava::Models::Stream
 streams.altitude # => Strava::Models::Stream
 ```
 
+The Strava API doesn't return a total elevation loss (descent) property for streams, but it can be computed from an altitude stream's data.
+
+```ruby
+streams = client.activity_streams(1946417534, keys: %w[altitude]) # => Strava::Models::StreamSet
+
+streams.altitude.total_elevation_gain # => 725.3
+streams.altitude.total_elevation_loss # => 680.1
+streams.altitude.total_elevation_gain_s # => "725.3m"
+streams.altitude.total_elevation_loss_s # => "680.1m"
+```
+
 #### Get Activity Streams
 
 Returns the given activity's streams.
diff --git a/lib/strava/models/stream.rb b/lib/strava/models/stream.rb
index ce39f7bd..87c99103 100644
--- a/lib/strava/models/stream.rb
+++ b/lib/strava/models/stream.rb
@@ -26,6 +26,11 @@ module Models
     #     puts "#{lat}, #{lng}"
     #   end
     #
+    # @example Computing elevation gain and loss from an altitude stream
+    #   streams = client.activity_streams(1234567890, keys: 'altitude')
+    #   puts streams.altitude.total_elevation_gain_s  # => "725.3m"
+    #   puts streams.altitude.total_elevation_loss_s  # => "680.1m"
+    #
     class Stream < Strava::Models::Response
       # @return [Integer] Total number of data points in the original stream before any resampling
       property 'original_size'
@@ -49,6 +54,66 @@ class Stream < Strava::Models::Response
       #   - moving: Array of booleans (true if moving, false if stopped)
       #   - grade_smooth: Array of floats (grade as percentage)
       property 'data'
+
+      #
+      # Returns the total elevation gain, calculated as the sum of all positive
+      # elevation increases between consecutive data points.
+      #
+      # This is only meaningful when the stream represents altitude data.
+      #
+      # @return [Float, nil] Total elevation gain in meters, or nil if data is not present
+      #
+      # @example
+      #   streams = client.activity_streams(1234567890, keys: 'altitude')
+      #   puts streams.altitude.total_elevation_gain # => 725.3
+      #
+      def total_elevation_gain
+        return if data.nil?
+
+        data.each_cons(2).sum { |a, b| b > a ? b - a : 0 }
+      end
+
+      #
+      # Returns the total elevation loss, calculated as the sum of all negative
+      # elevation decreases between consecutive data points.
+      #
+      # This is only meaningful when the stream represents altitude data.
+      #
+      # @return [Float, nil] Total elevation loss in meters, or nil if data is not present
+      #
+      # @example
+      #   streams = client.activity_streams(1234567890, keys: 'altitude')
+      #   puts streams.altitude.total_elevation_loss # => 680.1
+      #
+      def total_elevation_loss
+        return if data.nil?
+
+        data.each_cons(2).sum { |a, b| a > b ? a - b : 0 }
+      end
+
+      #
+      # Returns formatted total elevation gain in meters.
+      #
+      # @return [String, nil] Formatted elevation (e.g., "725.3m")
+      #
+      def total_elevation_gain_s
+        gain = total_elevation_gain
+        return if gain.nil?
+
+        format('%gm', format('%.1f', gain))
+      end
+
+      #
+      # Returns formatted total elevation loss in meters.
+      #
+      # @return [String, nil] Formatted elevation (e.g., "680.1m")
+      #
+      def total_elevation_loss_s
+        loss = total_elevation_loss
+        return if loss.nil?
+
+        format('%gm', format('%.1f', loss))
+      end
     end
   end
 end
diff --git a/spec/strava/api/client/endpoints/streams/segment_streams_spec.rb b/spec/strava/api/client/endpoints/streams/segment_streams_spec.rb
index cee02049..6db091bb 100644
--- a/spec/strava/api/client/endpoints/streams/segment_streams_spec.rb
+++ b/spec/strava/api/client/endpoints/streams/segment_streams_spec.rb
@@ -32,6 +32,10 @@
     expect(streams.distance).to be_a Strava::Models::Stream
     expect(streams.latlng).to be_a Strava::Models::Stream
     expect(streams.altitude).to be_a Strava::Models::Stream
+    expect(streams.altitude.total_elevation_gain).to eq 0
+    expect(streams.altitude.total_elevation_loss).to eq 3.3
+    expect(streams.altitude.total_elevation_gain_s).to eq '0m'
+    expect(streams.altitude.total_elevation_loss_s).to eq '3.3m'
   end
 
   it 'returns multiple keys by id', vcr: { cassette_name: 'client/segment_streams_keys' } do
@@ -46,5 +50,7 @@
     expect(streams.distance).to be_a Strava::Models::Stream
     expect(streams.latlng).to be_a Strava::Models::Stream
     expect(streams.altitude).to be_a Strava::Models::Stream
+    expect(streams.altitude.total_elevation_gain).to eq 0
+    expect(streams.altitude.total_elevation_loss).to eq 3.3
   end
 end
diff --git a/spec/strava/models/stream_spec.rb b/spec/strava/models/stream_spec.rb
new file mode 100644
index 00000000..e0e8ccff
--- /dev/null
+++ b/spec/strava/models/stream_spec.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Strava::Models::Stream do
+  describe '#total_elevation_gain' do
+    it 'sums positive elevation changes' do
+      stream = described_class.new('data' => [100, 105, 102, 110, 108])
+      expect(stream.total_elevation_gain).to eq 13
+    end
+
+    it 'returns 0 when there is no elevation gain' do
+      stream = described_class.new('data' => [100, 90, 80])
+      expect(stream.total_elevation_gain).to eq 0
+    end
+
+    it 'returns nil when data is nil' do
+      stream = described_class.new(nil)
+      expect(stream.total_elevation_gain).to be_nil
+    end
+  end
+
+  describe '#total_elevation_loss' do
+    it 'sums negative elevation changes' do
+      stream = described_class.new('data' => [100, 105, 102, 110, 108])
+      expect(stream.total_elevation_loss).to eq 5
+    end
+
+    it 'returns 0 when there is no elevation loss' do
+      stream = described_class.new('data' => [80, 90, 100])
+      expect(stream.total_elevation_loss).to eq 0
+    end
+
+    it 'returns nil when data is nil' do
+      stream = described_class.new(nil)
+      expect(stream.total_elevation_loss).to be_nil
+    end
+  end
+
+  describe '#total_elevation_gain_s' do
+    it 'returns formatted elevation gain' do
+      stream = described_class.new('data' => [100.0, 105.3, 102.1, 110.7, 108.2])
+      expect(stream.total_elevation_gain_s).to eq '13.9m'
+    end
+
+    it 'returns nil when data is nil' do
+      stream = described_class.new(nil)
+      expect(stream.total_elevation_gain_s).to be_nil
+    end
+  end
+
+  describe '#total_elevation_loss_s' do
+    it 'returns formatted elevation loss' do
+      stream = described_class.new('data' => [100.0, 105.3, 102.1, 110.7, 108.2])
+      expect(stream.total_elevation_loss_s).to eq '5.7m'
+    end
+
+    it 'returns nil when data is nil' do
+      stream = described_class.new(nil)
+      expect(stream.total_elevation_loss_s).to be_nil
+    end
+  end
+end