diff --git a/include/libcamera/internal/software_isp/swisp_stats.h b/include/libcamera/internal/software_isp/swisp_stats.h
index 65d826f6c..a0f6f4a79 100644
--- a/include/libcamera/internal/software_isp/swisp_stats.h
+++ b/include/libcamera/internal/software_isp/swisp_stats.h
@@ -17,7 +17,7 @@ namespace libcamera {
 /**
  * \brief Statistics for the Software ISP
  *
- * The software ISP computes two types of statistics:
+ * The software ISP computes the following types of statistics:
  *
  * - The accumulator counts the number of non-saturated pixels and sums their
  *   R, G and B channels individually. Pixels that have any saturated channel
@@ -27,6 +27,8 @@ namespace libcamera {
  * - The histogram groups pixels in bins based on their luminance and counts
  *   the number of pixels in each bin. Saturated pixels are included.
  *
+ * - The variance value for autofocus.
+ *
  * The value types are large enough to not overflow. Should they still overflow
  * for some reason, no check is performed and they wrap around.
  */
@@ -56,6 +58,10 @@ struct SwIspStats {
 	 * \brief A histogram of luminance values of all the sampled pixels
 	 */
 	Histogram yHistogram;
+	/**
+	 * \brief A variance value for the autofocus algorithm
+	 */
+	double variance;
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/software_isp/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp
index 0aa5597a9..ed1aa83e4 100644
--- a/src/libcamera/software_isp/swstats_cpu.cpp
+++ b/src/libcamera/software_isp/swstats_cpu.cpp
@@ -407,6 +407,7 @@ void SwStatsCpu::startFrame(uint32_t frame)
 	for (auto &s : stats_) {
 		s.sum_ = RGB<uint64_t>({ 0, 0, 0 });
 		s.numPixels_ = 0;
+		s.variance = 0.0;
 		s.yHistogram.fill(0);
 	}
 }
@@ -425,10 +426,12 @@ void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId)
 	if (valid) {
 		sharedStats_->sum_ = RGB<uint64_t>({ 0, 0, 0 });
 		sharedStats_->numPixels_ = 0;
+		sharedStats_->variance = 0.0;
 		sharedStats_->yHistogram.fill(0);
 		for (const auto &s : stats_) {
 			sharedStats_->sum_ += s.sum_;
 			sharedStats_->numPixels_ += s.numPixels_;
+			sharedStats_->variance += s.variance;
 			for (unsigned int j = 0; j < SwIspStats::kYHistogramSize; j++)
 				sharedStats_->yHistogram[j] += s.yHistogram[j];
 		}