diff --git a/NEWS.md b/NEWS.md
index a4bce3f6be..85999a742e 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* Default aesthetics in stats are now evaluated prior to computation 
+  (@teunbrand, #3860).
 * The `summary()` method for ggplots is now more terse about facets 
   (@teunbrand, #5989).
 * `guide_bins()`, `guide_colourbar()` and `guide_coloursteps()` gain an `angle`
diff --git a/R/layer.R b/R/layer.R
index 8acb438c9e..ae1ef23888 100644
--- a/R/layer.R
+++ b/R/layer.R
@@ -58,8 +58,8 @@
 #'   `NA`, the default, includes if any aesthetics are mapped.
 #'   `FALSE` never includes, and `TRUE` always includes.
 #'   It can also be a named logical vector to finely select the aesthetics to
-#'   display. To include legend keys for all levels, even 
-#'   when no data exists, use `TRUE`.  If `NA`, all levels are shown in legend, 
+#'   display. To include legend keys for all levels, even
+#'   when no data exists, use `TRUE`.  If `NA`, all levels are shown in legend,
 #'   but unobserved levels are omitted.
 #' @param inherit.aes If `FALSE`, overrides the default aesthetics,
 #'   rather than combining with them. This is most useful for helper functions
@@ -362,6 +362,7 @@ Layer <- ggproto("Layer", NULL,
       return(data_frame0())
 
     self$computed_stat_params <- self$stat$setup_params(data, self$stat_params)
+    data <- self$stat$use_defaults(data)
     data <- self$stat$setup_data(data, self$computed_stat_params)
     self$stat$compute_layer(data, self$computed_stat_params, layout)
   },
diff --git a/R/stat-.R b/R/stat-.R
index 2d56937b06..f26090cf6c 100644
--- a/R/stat-.R
+++ b/R/stat-.R
@@ -215,6 +215,33 @@ Stat <- ggproto("Stat",
       required_aes <- unlist(strsplit(self$required_aes, '|', fixed = TRUE))
     }
     c(union(required_aes, names(self$default_aes)), self$optional_aes, "group")
-  }
+  },
+
+  use_defaults = function(self, data, default_aes = NULL) {
+    default_aes <- default_aes %||% self$default_aes
+    if (length(default_aes) == 0) {
+      return(data)
+    }
+
+    missing_aes <- setdiff(names(default_aes), names(data))
+    default_aes <- default_aes[missing_aes]
+
+    delayed <- is_calculated_aes(default_aes) | is_staged_aes(default_aes) |
+      is_scaled_aes(default_aes)
+    default_aes <- default_aes[!delayed]
+
+    if (length(default_aes) == 0) {
+      return(data)
+    }
+
+    evaled <- compact(lapply(default_aes, eval_tidy))
 
+    if (empty(data)) {
+      data <- as_gg_data_frame(evaled)
+    } else {
+      data[names(evaled)] <- evaled
+    }
+
+    data
+  }
 )
diff --git a/R/stat-bin2d.R b/R/stat-bin2d.R
index 69f57ebee3..31166b0e6d 100644
--- a/R/stat-bin2d.R
+++ b/R/stat-bin2d.R
@@ -66,9 +66,6 @@ StatBin2d <- ggproto("StatBin2d", Stat,
     xbin <- cut(data$x, xbreaks, include.lowest = TRUE, labels = FALSE)
     ybin <- cut(data$y, ybreaks, include.lowest = TRUE, labels = FALSE)
 
-    if (is.null(data$weight))
-      data$weight <- 1
-
     out <- tapply_df(data$weight, list(xbin = xbin, ybin = ybin), sum, drop = drop)
 
     xdim <- bin_loc(xbreaks, out$xbin)
diff --git a/R/stat-bindot.R b/R/stat-bindot.R
index 85eecc4d54..273e0e8962 100644
--- a/R/stat-bindot.R
+++ b/R/stat-bindot.R
@@ -5,8 +5,7 @@
 StatBindot <- ggproto("StatBindot", Stat,
   required_aes = "x",
   non_missing_aes = "weight",
-  default_aes = aes(y = after_stat(count)),
-  dropped_aes = c("bin", "bincenter"), # these are temporary variables that are created and then removed by the stat
+  default_aes = aes(y = after_stat(count), weight = 1L),
 
   setup_params = function(data, params) {
     if (is.null(params$binwidth)) {
@@ -126,6 +125,7 @@ StatBindot <- ggproto("StatBindot", Stat,
     return(data)
   },
 
+  # these are temporary variables that are created and then removed by the stat
   dropped_aes = c("weight", "bin", "bincenter")
 )
 
diff --git a/R/stat-binhex.R b/R/stat-binhex.R
index 0b5d3991c6..77c2839fc5 100644
--- a/R/stat-binhex.R
+++ b/R/stat-binhex.R
@@ -51,8 +51,7 @@ StatBinhex <- ggproto("StatBinhex", Stat,
     check_installed("hexbin", reason = "for `stat_bin_hex()`.")
 
     binwidth <- binwidth %||% hex_binwidth(bins, scales)
-    wt <- data$weight %||% rep(1L, nrow(data))
-    out <- hexBinSummarise(data$x, data$y, wt, binwidth, sum)
+    out <- hexBinSummarise(data$x, data$y, data$weight, binwidth, sum)
     out$density <- as.vector(out$value / sum(out$value, na.rm = TRUE))
     out$ndensity <- out$density / max(out$density, na.rm = TRUE)
     out$count <- out$value
diff --git a/R/stat-boxplot.R b/R/stat-boxplot.R
index 46ce14879f..c0f107a61d 100644
--- a/R/stat-boxplot.R
+++ b/R/stat-boxplot.R
@@ -48,13 +48,12 @@ stat_boxplot <- function(mapping = NULL, data = NULL,
 #' @export
 StatBoxplot <- ggproto("StatBoxplot", Stat,
   required_aes = c("y|x"),
-  non_missing_aes = "weight",
+  default_aes = aes(x = 0, y = 0),
   # either the x or y aesthetic will get dropped during
   # statistical transformation, depending on the orientation
   dropped_aes = c("x", "y", "weight"),
   setup_data = function(self, data, params) {
     data <- flip_data(data, params$flipped_aes)
-    data$x <- data$x %||% 0
     data <- remove_missing(
       data,
       na.rm = params$na.rm,
@@ -118,7 +117,7 @@ StatBoxplot <- ggproto("StatBoxplot", Stat,
       n <- sum(!is.na(data$y))
     } else {
       # Sum up weights for non-NA positions of y and weight
-      n <- sum(data$weight[!is.na(data$y) & !is.na(data$weight)])
+    n <- sum(data$weight[!is.na(data$y) & !is.na(data$weight)])
     }
 
     df$notchupper <- df$middle + 1.58 * iqr / sqrt(n)
diff --git a/R/stat-count.R b/R/stat-count.R
index fd78d1beaa..e694f93713 100644
--- a/R/stat-count.R
+++ b/R/stat-count.R
@@ -70,15 +70,13 @@ StatCount <- ggproto("StatCount", Stat,
 
   compute_group = function(self, data, scales, width = NULL, flipped_aes = FALSE) {
     data <- flip_data(data, flipped_aes)
-    x <- data$x
-    weight <- data$weight %||% rep(1, length(x))
 
-    count <- as.vector(rowsum(weight, x, na.rm = TRUE))
+    count <- as.vector(rowsum(data$weight, data$x, na.rm = TRUE))
 
     bars <- data_frame0(
       count = count,
       prop = count / sum(abs(count)),
-      x = sort(unique0(x)),
+      x = sort(unique0(data$x)),
       width = width,
       flipped_aes = flipped_aes,
       .size = length(count)
diff --git a/R/stat-quantilemethods.R b/R/stat-quantilemethods.R
index 9afb7e0b92..c7e6732124 100644
--- a/R/stat-quantilemethods.R
+++ b/R/stat-quantilemethods.R
@@ -46,6 +46,8 @@ stat_quantile <- function(mapping = NULL, data = NULL,
 StatQuantile <- ggproto("StatQuantile", Stat,
   required_aes = c("x", "y"),
 
+  default_aes = aes(weight = 1),
+
   compute_group = function(data, scales, quantiles = c(0.25, 0.5, 0.75),
                            formula = NULL, xseq = NULL, method = "rq",
                            method.args = list(), lambda = 1, na.rm = FALSE) {
@@ -66,8 +68,6 @@ StatQuantile <- ggproto("StatQuantile", Stat,
       cli::cli_inform("Smoothing formula not specified. Using: {deparse(formula)}")
     }
 
-    if (is.null(data$weight)) data$weight <- 1
-
     if (is.null(xseq)) {
       xmin <- min(data$x, na.rm = TRUE)
       xmax <- max(data$x, na.rm = TRUE)
diff --git a/R/stat-smooth.R b/R/stat-smooth.R
index 147bd06e41..fa1dcd69c7 100644
--- a/R/stat-smooth.R
+++ b/R/stat-smooth.R
@@ -157,6 +157,8 @@ StatSmooth <- ggproto("StatSmooth", Stat,
 
   extra_params = c("na.rm", "orientation"),
 
+  default_aes = aes(weight = 1),
+
   compute_group = function(data, scales, method = NULL, formula = NULL,
                            se = TRUE, n = 80, span = 0.75, fullrange = FALSE,
                            xseq = NULL, level = 0.95, method.args = list(),
@@ -167,8 +169,6 @@ StatSmooth <- ggproto("StatSmooth", Stat,
       return(data_frame0())
     }
 
-    if (is.null(data$weight)) data$weight <- 1
-
     if (is.null(xseq)) {
       if (is.integer(data$x)) {
         if (fullrange) {