diff --git a/libnopegl/src/backends/gl/gpu_ctx_gl.c b/libnopegl/src/backends/gl/gpu_ctx_gl.c
index 5967dfa76..1b3ec268d 100644
--- a/libnopegl/src/backends/gl/gpu_ctx_gl.c
+++ b/libnopegl/src/backends/gl/gpu_ctx_gl.c
@@ -927,6 +927,12 @@ static const struct rendertarget_layout *gl_get_default_rendertarget_layout(stru
     return &s_priv->default_rt_layout;
 }
 
+static void gl_get_default_rendertarget_size(struct gpu_ctx *s, int32_t *width, int32_t *height)
+{
+    *width = s->config.width;
+    *height = s->config.height;
+}
+
 static void gl_begin_render_pass(struct gpu_ctx *s, struct rendertarget *rt)
 {
     ngli_rendertarget_gl_begin_pass(rt);
@@ -1015,6 +1021,7 @@ const struct gpu_ctx_class ngli_gpu_ctx_##cls_suffix = {
                                                                                  \
     .get_default_rendertarget           = gl_get_default_rendertarget,           \
     .get_default_rendertarget_layout    = gl_get_default_rendertarget_layout,    \
+    .get_default_rendertarget_size      = gl_get_default_rendertarget_size,      \
                                                                                  \
     .begin_render_pass                  = gl_begin_render_pass,                  \
     .end_render_pass                    = gl_end_render_pass,                    \
diff --git a/libnopegl/src/backends/vk/gpu_ctx_vk.c b/libnopegl/src/backends/vk/gpu_ctx_vk.c
index 7b421fea8..d12858970 100644
--- a/libnopegl/src/backends/vk/gpu_ctx_vk.c
+++ b/libnopegl/src/backends/vk/gpu_ctx_vk.c
@@ -1277,6 +1277,13 @@ static const struct rendertarget_layout *vk_get_default_rendertarget_layout(stru
     return &s_priv->default_rt_layout;
 }
 
+static void vk_get_default_rendertarget_size(struct gpu_ctx *s, int32_t *width, int32_t *height)
+{
+    struct gpu_ctx_vk *s_priv = (struct gpu_ctx_vk *)s;
+    *width = s_priv->width;
+    *height = s_priv->height;
+}
+
 static void vk_begin_render_pass(struct gpu_ctx *s, struct rendertarget *rt)
 {
     struct gpu_ctx_vk *s_priv = (struct gpu_ctx_vk *)s;
@@ -1470,6 +1477,7 @@ const struct gpu_ctx_class ngli_gpu_ctx_vk = {
 
     .get_default_rendertarget           = vk_get_default_rendertarget,
     .get_default_rendertarget_layout    = vk_get_default_rendertarget_layout,
+    .get_default_rendertarget_size      = vk_get_default_rendertarget_size,
 
     .begin_render_pass                  = vk_begin_render_pass,
     .end_render_pass                    = vk_end_render_pass,
diff --git a/libnopegl/src/gpu_ctx.c b/libnopegl/src/gpu_ctx.c
index 725c4b22b..b6e84e175 100644
--- a/libnopegl/src/gpu_ctx.c
+++ b/libnopegl/src/gpu_ctx.c
@@ -203,6 +203,11 @@ const struct rendertarget_layout *ngli_gpu_ctx_get_default_rendertarget_layout(s
     return s->cls->get_default_rendertarget_layout(s);
 }
 
+void ngli_gpu_ctx_get_default_rendertarget_size(struct gpu_ctx *s, int32_t *width, int32_t *height)
+{
+    s->cls->get_default_rendertarget_size(s, width, height);
+}
+
 void ngli_gpu_ctx_set_viewport(struct gpu_ctx *s, const struct viewport *viewport)
 {
     s->viewport = *viewport;
diff --git a/libnopegl/src/gpu_ctx.h b/libnopegl/src/gpu_ctx.h
index e8f4eff1d..a9a6ce4de 100644
--- a/libnopegl/src/gpu_ctx.h
+++ b/libnopegl/src/gpu_ctx.h
@@ -71,6 +71,7 @@ struct gpu_ctx_class {
 
     struct rendertarget *(*get_default_rendertarget)(struct gpu_ctx *s, int load_op);
     const struct rendertarget_layout *(*get_default_rendertarget_layout)(struct gpu_ctx *s);
+    void (*get_default_rendertarget_size)(struct gpu_ctx *s, int32_t *width, int32_t *height);
 
     void (*begin_render_pass)(struct gpu_ctx *s, struct rendertarget *rt);
     void (*end_render_pass)(struct gpu_ctx *s);
@@ -172,6 +173,7 @@ void ngli_gpu_ctx_get_rendertarget_uvcoord_matrix(struct gpu_ctx *s, float *dst)
 
 struct rendertarget *ngli_gpu_ctx_get_default_rendertarget(struct gpu_ctx *s, int load_op);
 const struct rendertarget_layout *ngli_gpu_ctx_get_default_rendertarget_layout(struct gpu_ctx *s);
+void ngli_gpu_ctx_get_default_rendertarget_size(struct gpu_ctx *s, int32_t *width, int32_t *height);
 
 void ngli_gpu_ctx_begin_render_pass(struct gpu_ctx *s, struct rendertarget *rt);
 void ngli_gpu_ctx_end_render_pass(struct gpu_ctx *s);