diff --git a/src/bigints.nim b/src/bigints.nim
index 9ef5abb..fe1498c 100644
--- a/src/bigints.nim
+++ b/src/bigints.nim
@@ -1,6 +1,6 @@
 ## Arbitrary precision integers.
 
-import std/[algorithm, bitops, math, options]
+import std/[algorithm, bitops, fenv, math, options]
 
 type
   BigInt* = object
@@ -1140,6 +1140,12 @@ func fastLog2*(a: BigInt): int =
     return -1
   bitops.fastLog2(a.limbs[^1]) + 32*(a.limbs.high)
 
+func to*(x: BigInt, T:type SomeFloat): T =
+  let lolimb = max(x.limbs.low, x.limbs.high - 1 - mantissaDigits(T) div 32)
+  for i in lolimb..x.limbs.high:
+    result += T(x.limbs[i].int64) * pow(2.0, 32.0 * T(i))
+  if x.isNegative:
+    result = -result
 
 func invmod*(a, modulus: BigInt): BigInt =
   ## Compute the modular inverse of `a` modulo `modulus`.
diff --git a/tests/tbigints.nim b/tests/tbigints.nim
index 3b3a59d..c3fd267 100644
--- a/tests/tbigints.nim
+++ b/tests/tbigints.nim
@@ -786,6 +786,35 @@ proc main() =
     doAssert pred(a, 3) == initBigInt(4)
     doAssert succ(a, 3) == initBigInt(10)
 
+  block: # to float
+    doAssert initBigInt("1").to(float32) is float32
+    doAssert initBigInt("1").to(float64) is float64
+    doAssert initBigInt("1").to(BiggestFloat) is BiggestFloat
+    doAssert initBigInt("1").to(float) is float
+
+    doAssert initBigInt("0").to(BiggestFloat) == 0.0
+    doAssert initBigInt("1").to(BiggestFloat) == 1.0
+    doAssert initBigInt("1").to(float32) == 1.0
+    doAssert initBigInt("1").to(float64) == 1.0
+
+    doAssert initBigInt("-1").to(BiggestFloat) == -1.0
+    doAssert initBigInt(BiggestInt.high).to(BiggestFloat) == BiggestFloat(BiggestInt.high)
+    doAssert initBigInt(BiggestInt.low).to(BiggestFloat) == BiggestFloat(BiggestInt.low)
+    doAssert (initBigInt(BiggestInt.high) * initBigInt(4)).to(BiggestFloat) == BiggestFloat(BiggestInt.high) * 4.0
+    doAssert (initBigInt(BiggestInt.low) * initBigInt(4)).to(BiggestFloat) == BiggestFloat(BiggestInt.low) * 4.0
+    doAssert (initBigInt("17976931348623157") * initBigInt(10).pow(292)).to(BiggestFloat) == 17976931348623157e292
+
+    # limits of exact representability
+    doAssert initBigInt(1 shl 24).to(float32) == float32(1 shl 24)
+    doAssert initBigInt(-1 shl 24).to(float32) == float32(-1 shl 24)
+    doAssert initBigInt(1 shl 53).to(float64) == float64(1 shl 53)
+    doAssert initBigInt(-1 shl 53).to(float64) == float64(-1 shl 53)
+    # out of exact integer representation range
+    doAssert initBigInt(int32.high).to(float32) == float32(int32.high)
+    doAssert initBigInt(int64.high).to(float64) == float64(int64.high)
+    # well out out of finite range
+    doAssert initBigInt("-10").pow(400).to(float64) == Inf
+    doAssert initBigInt("-10").pow(401).to(float64) == -Inf
 
 static: main()
 main()