diff --git a/ts/lib/tslib/time.ts b/ts/lib/tslib/time.ts
index a517e8a39..876f66b27 100644
--- a/ts/lib/tslib/time.ts
+++ b/ts/lib/tslib/time.ts
@@ -7,8 +7,8 @@ export const SECOND = 1.0;
 export const MINUTE = 60.0 * SECOND;
 export const HOUR = 60.0 * MINUTE;
 export const DAY = 24.0 * HOUR;
-export const MONTH = 30.417 * DAY; // 365/12 ≈ 30.417
 export const YEAR = 365.0 * DAY;
+export const MONTH = YEAR / 12;
 
 export enum TimespanUnit {
     Seconds,
@@ -36,21 +36,25 @@ export function unitName(unit: TimespanUnit): string {
     }
 }
 
-export function naturalUnit(secs: number): TimespanUnit {
+export function naturalUnit(secs: number, maxUnit: TimespanUnit = TimespanUnit.Years): TimespanUnit {
     secs = Math.abs(secs);
-    if (secs < MINUTE) {
-        return TimespanUnit.Seconds;
-    } else if (secs < HOUR) {
-        return TimespanUnit.Minutes;
-    } else if (secs < DAY) {
-        return TimespanUnit.Hours;
-    } else if (secs < MONTH) {
-        return TimespanUnit.Days;
-    } else if (secs < YEAR) {
-        return TimespanUnit.Months;
-    } else {
-        return TimespanUnit.Years;
+    const thresholds = [
+        { unit: TimespanUnit.Years, min: YEAR },
+        { unit: TimespanUnit.Months, min: MONTH },
+        { unit: TimespanUnit.Days, min: DAY },
+        { unit: TimespanUnit.Hours, min: HOUR },
+        { unit: TimespanUnit.Minutes, min: MINUTE },
+        { unit: TimespanUnit.Seconds, min: 0 },
+    ];
+    for (const { unit, min } of thresholds) {
+        if (unit > maxUnit) {
+            continue;
+        }
+        if (secs >= min) {
+            return unit;
+        }
     }
+    return TimespanUnit.Seconds;
 }
 
 /** Number of seconds in a given unit. */
@@ -146,8 +150,13 @@ function i18nFuncForUnit(
 If precise is true, show to two decimal places, eg
 eg 70 seconds -> "1.17 minutes"
 If false, seconds and days are shown without decimals. */
-export function timeSpan(seconds: number, short = false, precise = true): string {
-    const unit = naturalUnit(seconds);
+export function timeSpan(
+    seconds: number,
+    short = false,
+    precise = true,
+    maxUnit: TimespanUnit = TimespanUnit.Years,
+): string {
+    const unit = naturalUnit(seconds, maxUnit);
     let amount = unitAmount(unit, seconds);
     if (!precise && unit < TimespanUnit.Months) {
         amount = Math.round(amount);