diff --git a/ana/prediction.go b/ana/prediction.go
index 2872af8..ef32d79 100644
--- a/ana/prediction.go
+++ b/ana/prediction.go
@@ -1,3 +1,44 @@
 package ana
 
+import (
+	"maps"
+	"time"
+
+	"gogs.inhome.blapointe.com/ana-ledger/ledger"
+)
+
 type Prediction []Predictor
+
+func NewPrediction(predictor ...Predictor) Prediction {
+	return Prediction(predictor)
+}
+
+func (prediction Prediction) Predict(register ledger.Register, window time.Duration) ledger.Register {
+	return prediction.predict(register.Latest(), time.Now(), predictionTimes(window))
+}
+
+func (prediction Prediction) predict(latest ledger.Balances, from time.Time, these []time.Time) ledger.Register {
+	latestT := from
+	result := make(ledger.Register)
+	for i := range these {
+		k := these[i].Format("2006-01")
+		result[k] = make(ledger.Balances)
+		for k2, v2 := range result[k] {
+			result[k][k2] = maps.Clone(v2)
+		}
+
+		elapsed := these[i].Sub(latestT)
+		result[k] = prediction.predictOne(result[k], elapsed)
+
+		latest = result[k]
+		latestT = these[i]
+	}
+	return result
+}
+
+func (prediction Prediction) predictOne(balances ledger.Balances, elapsed time.Duration) ledger.Balances {
+	for i := range prediction {
+		balances = prediction[i](balances, elapsed)
+	}
+	return balances
+}
diff --git a/ana/prediction_test.go b/ana/prediction_test.go
new file mode 100644
index 0000000..d5b7b04
--- /dev/null
+++ b/ana/prediction_test.go
@@ -0,0 +1,54 @@
+package ana
+
+import (
+	"fmt"
+	"maps"
+	"testing"
+	"time"
+
+	"gogs.inhome.blapointe.com/ana-ledger/ledger"
+)
+
+func TestPredictionPredict(t *testing.T) {
+	inc := func(b ledger.Balances, _ time.Duration) ledger.Balances {
+		result := make(ledger.Balances)
+		for k, v := range b {
+			result[k] = maps.Clone(v)
+			for k2, v2 := range result[k] {
+				result[k][k2] = v2 + 1
+			}
+		}
+		return result
+	}
+	double := func(b ledger.Balances, _ time.Duration) ledger.Balances {
+		result := make(ledger.Balances)
+		for k, v := range b {
+			result[k] = maps.Clone(v)
+			for k2, v2 := range result[k] {
+				result[k][k2] = v2 * 2
+			}
+		}
+		return result
+	}
+	from := time.Now()
+	these := []time.Time{time.Now().Add(time.Hour * 24 * 365 / 12)}
+	_, _ = inc, double
+
+	cases := map[string]struct {
+		prediction Prediction
+		given      ledger.Balances
+		want       ledger.Register
+	}{
+		"empty": {},
+	}
+
+	for name, d := range cases {
+		c := d
+		t.Run(name, func(t *testing.T) {
+			got := c.prediction.predict(c.given, from, these)
+			if fmt.Sprintf("%+v", got) != fmt.Sprintf("%+v", c.want) {
+				t.Errorf("want\n\t%+v, got\n\t%+v", c.want, got)
+			}
+		})
+	}
+}
diff --git a/ledger/register.go b/ledger/register.go
index 9dc66c0..b223c7d 100644
--- a/ledger/register.go
+++ b/ledger/register.go
@@ -9,6 +9,15 @@ import (
 
 type Register map[string]Balances
 
+func (register Register) Latest() Balances {
+	dates := register.Dates()
+	if len(dates) == 0 {
+		return nil
+	}
+	date := dates[len(dates)-1]
+	return register[date]
+}
+
 func (register Register) WithBPIs(bpis BPIs) Register {
 	result := make(Register)
 	for d := range register {