diff --git a/assets/js/components/Sessions/CostHistoryChart.vue b/assets/js/components/Sessions/CostHistoryChart.vue
index b7586afcc..59dbe09f0 100644
--- a/assets/js/components/Sessions/CostHistoryChart.vue
+++ b/assets/js/components/Sessions/CostHistoryChart.vue
@@ -47,6 +47,7 @@ export default {
 		period: { type: String, default: PERIODS.TOTAL },
 		currency: { type: String, default: "EUR" },
 		colorMappings: { type: Object, default: () => ({ loadpoint: {}, vehicle: {} }) },
+		suggestedMaxAvgCost: { type: Number, default: 0 },
 		suggestedMaxCost: { type: Number, default: 0 },
 	},
 	computed: {
@@ -313,12 +314,13 @@ export default {
 							color: colors.muted,
 							maxTicksLimit: 6,
 						},
+						suggestedMax: this.suggestedMaxCost,
 						min: 0,
 					},
 					y1: {
 						position: "left",
 						border: { display: false },
-						suggestedMax: this.suggestedMaxCost,
+						suggestedMax: this.suggestedMaxAvgCost,
 						grid: {
 							drawOnChartArea: false,
 						},
diff --git a/assets/js/views/Sessions.vue b/assets/js/views/Sessions.vue
index 6b74a777b..8e07ae841 100644
--- a/assets/js/views/Sessions.vue
+++ b/assets/js/views/Sessions.vue
@@ -96,6 +96,7 @@
 					:cost-type="activeType"
 					:currency="currency"
 					:period="period"
+					:suggested-max-avg-cost="suggestedMaxAvgCost"
 					:suggested-max-cost="suggestedMaxCost"
 				/>
 				<div v-if="showExtraCharts" class="row align-items-start">
@@ -118,7 +119,7 @@
 							v-else
 							:sessions="currentTypeSessions"
 							:color-mappings="colorMappings"
-							:suggested-max-price="suggestedMaxCost"
+							:suggested-max-price="suggestedMaxAvgCost"
 							:group-by="selectedGroup"
 							:cost-type="activeType"
 							:currency="currency"
@@ -594,17 +595,42 @@ export default {
 
 			return (isGrouped && hasMultipleEntries) || (isSolar && isNotMonth && !isGrouped);
 		},
-		suggestedMaxPrice() {
-			// returns the 90th percentile of all prices
+		suggestedMaxAvgPrice() {
+			// returns the 98th percentile of avg prices for all sessions
 			const sessionsWithPrice = this.sessions.filter((s) => s.pricePerKWh !== null);
 			const prices = sessionsWithPrice.map((s) => s.pricePerKWh);
-			return this.percentile(prices, 90);
+			return this.percentile(prices, 98);
 		},
-		suggestedMaxCo2() {
-			// returns the 90th percentile of all co2 emissions
+		suggestedMaxAvgCo2() {
+			// returns the 98th percentile of avg co2 emissions for all sessions
 			const sessionsWithCo2 = this.sessions.filter((s) => s.co2PerKWh !== null);
 			const co2 = sessionsWithCo2.map((s) => s.co2PerKWh);
-			return this.percentile(co2, 90);
+			return this.percentile(co2, 98);
+		},
+		suggestedMaxAvgCost() {
+			return this.activeType === TYPES.PRICE
+				? this.suggestedMaxAvgPrice
+				: this.suggestedMaxAvgCo2;
+		},
+		suggestedMaxCo2() {
+			// returns the 98th percentile of total co2 emissions by time period
+			const sessionsWithCo2 = this.sessions.filter((s) => s.co2PerKWh !== null);
+			const co2Map = sessionsWithCo2.reduce((acc, s) => {
+				const key = this.dateToPeriodKey(new Date(s.created));
+				acc[key] = (acc[key] || 0) + s.co2PerKWh * s.chargedEnergy;
+				return acc;
+			}, {});
+			return Math.max(this.percentile(Object.values(co2Map), 98), 5); // 5kg default
+		},
+		suggestedMaxPrice() {
+			// returns the 98th percentile of total price by time period
+			const sessionsWithPrice = this.sessions.filter((s) => s.price !== null);
+			const priceMap = sessionsWithPrice.reduce((acc, s) => {
+				const key = this.dateToPeriodKey(new Date(s.created));
+				acc[key] = (acc[key] || 0) + s.price;
+				return acc;
+			}, {});
+			return Math.max(this.percentile(Object.values(priceMap), 98), 1); // 1 CURRENCY default
 		},
 		suggestedMaxCost() {
 			return this.activeType === TYPES.PRICE ? this.suggestedMaxPrice : this.suggestedMaxCo2;
@@ -636,6 +662,12 @@ export default {
 			}
 			this.$router.push({ query: { ...this.$route.query, period, month, year } });
 		},
+		dateToPeriodKey(date) {
+			const options = { year: "numeric", month: "numeric", day: "numeric" };
+			if (this.period === PERIODS.YEAR) options.day = undefined;
+			if (this.period === PERIODS.TOTAL) options.month = undefined;
+			return date.toLocaleDateString(undefined, options);
+		},
 		async loadSessions() {
 			const response = await api.get("sessions");
 			// ensure sessions are sorted by created date