diff --git a/polkadot/runtime/polkadot/src/constants.rs b/polkadot/runtime/polkadot/src/constants.rs
index 27affd820e649d40525fea1172901db838f2a8e0..9b6ea042655909302c906b1b149ea1a18fb63bea 100644
--- a/polkadot/runtime/polkadot/src/constants.rs
+++ b/polkadot/runtime/polkadot/src/constants.rs
@@ -19,9 +19,9 @@ pub mod currency {
 	use primitives::Balance;
 
 	pub const DOTS: Balance = 1_000_000_000_000;
-	pub const DOLLARS: Balance = DOTS / 100;
-	pub const CENTS: Balance = DOLLARS / 100;
-	pub const MILLICENTS: Balance = CENTS / 1_000;
+	pub const DOLLARS: Balance = DOTS / 100;       // 10_000_000_000
+	pub const CENTS: Balance = DOLLARS / 100;      // 100_000_000
+	pub const MILLICENTS: Balance = CENTS / 1_000; // 100_000
 }
 
 /// Time and blocks.
diff --git a/polkadot/runtime/polkadot/tests/weights.rs b/polkadot/runtime/polkadot/tests/weights.rs
new file mode 100644
index 0000000000000000000000000000000000000000..6bfe1dced4e7f43d04b18adfb6075cc986cbd090
--- /dev/null
+++ b/polkadot/runtime/polkadot/tests/weights.rs
@@ -0,0 +1,275 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Tests to make sure that Polkadot's weights and fees match what we
+//! expect from Substrate.
+//!
+//! These test are not meant to be exhaustive, as it is inevitable that
+//! weights in Substrate will change. Instead they are supposed to provide
+//! some sort of indicator that calls we consider important (e.g Balances::transfer)
+//! have not suddenly changed from under us.
+
+use frame_support::{
+	traits::ContainsLengthBound,
+	weights::{constants::*, GetDispatchInfo, Weight},
+};
+use keyring::AccountKeyring;
+use polkadot_runtime::constants::currency::*;
+use polkadot_runtime::{self, Runtime};
+use primitives::AccountId;
+use runtime_common::MaximumBlockWeight;
+
+use democracy::Call as DemocracyCall;
+use elections_phragmen::Call as PhragmenCall;
+use session::Call as SessionCall;
+use staking::Call as StakingCall;
+use system::Call as SystemCall;
+use treasury::Call as TreasuryCall;
+
+type DbWeight = <Runtime as system::Trait>::DbWeight;
+
+#[test]
+fn sanity_check_weight_per_time_constants_are_as_expected() {
+	// These values comes from Substrate, we want to make sure that if it
+	// ever changes we don't accidently break Polkadot
+	assert_eq!(WEIGHT_PER_SECOND, 1_000_000_000_000);
+	assert_eq!(WEIGHT_PER_MILLIS, WEIGHT_PER_SECOND / 1000);
+	assert_eq!(WEIGHT_PER_MICROS, WEIGHT_PER_MILLIS / 1000);
+	assert_eq!(WEIGHT_PER_NANOS, WEIGHT_PER_MICROS / 1000);
+}
+
+#[test]
+fn weight_of_balances_transfer_is_correct() {
+	// #[weight = T::DbWeight::get().reads_writes(1, 1) + 70_000_000]
+	let expected_weight = DbWeight::get().read + DbWeight::get().write + 70_000_000;
+
+	let weight = polkadot_runtime::BalancesCall::transfer::<Runtime>(Default::default(), Default::default())
+		.get_dispatch_info()
+		.weight;
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_balances_transfer_keep_alive_is_correct() {
+	// #[weight = T::DbWeight::get().reads_writes(1, 1) + 50_000_000]
+	let expected_weight = DbWeight::get().read + DbWeight::get().write + 50_000_000;
+
+	let weight = polkadot_runtime::BalancesCall::transfer_keep_alive::<Runtime>(Default::default(), Default::default())
+		.get_dispatch_info()
+		.weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_timestamp_set_is_correct() {
+	// #[weight = T::DbWeight::get().reads_writes(2, 1) + 8_000_000]
+	let expected_weight = (2 * DbWeight::get().read) + DbWeight::get().write + 8_000_000;
+	let weight = polkadot_runtime::TimestampCall::set::<Runtime>(Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_staking_bond_is_correct() {
+	let controller: AccountId = AccountKeyring::Alice.into();
+
+	// #[weight = 67 * WEIGHT_PER_MICROS + T::DbWeight::get().reads_writes(5, 4)]
+	let expected_weight = 67 * WEIGHT_PER_MICROS + (DbWeight::get().read * 5) + (DbWeight::get().write * 4);
+	let weight = StakingCall::bond::<Runtime>(controller, 1 * DOLLARS, Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_staking_validate_is_correct() {
+	// #[weight = 17 * WEIGHT_PER_MICROS + T::DbWeight::get().reads_writes(2, 2)]
+	let expected_weight = 17 * WEIGHT_PER_MICROS + (DbWeight::get().read * 2) + (DbWeight::get().write * 2);
+	let weight = StakingCall::validate::<Runtime>(Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_staking_nominate_is_correct() {
+	let targets: Vec<AccountId> = vec![Default::default(), Default::default(), Default::default()];
+
+	// #[weight = T::DbWeight::get().reads_writes(3, 2)
+	// 	.saturating_add(22 * WEIGHT_PER_MICROS)
+	// 	.saturating_add((360 * WEIGHT_PER_NANOS).saturating_mul(targets.len() as Weight))
+	// ]
+	let db_weight = (DbWeight::get().read * 3) + (DbWeight::get().write * 2);
+	let targets_weight = (360 * WEIGHT_PER_NANOS).saturating_mul(targets.len() as Weight);
+
+	let expected_weight = db_weight.saturating_add(22 * WEIGHT_PER_MICROS).saturating_add(targets_weight);
+	let weight = StakingCall::nominate::<Runtime>(targets).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_system_set_code_is_correct() {
+	// #[weight = (T::MaximumBlockWeight::get(), DispatchClass::Operational)]
+	let expected_weight = MaximumBlockWeight::get();
+	let weight = SystemCall::set_code::<Runtime>(vec![]).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_system_set_storage_is_correct() {
+	let storage_items = vec![(vec![12], vec![34]), (vec![45], vec![83])];
+	let len = storage_items.len() as Weight;
+
+	// #[weight = FunctionOf(
+	// 	|(items,): (&Vec<KeyValue>,)| {
+	// 		T::DbWeight::get().writes(items.len() as Weight)
+	// 			.saturating_add((items.len() as Weight).saturating_mul(600_000))
+	// 	},
+	// 	DispatchClass::Operational,
+	// 	Pays::Yes,
+	// )]
+	let expected_weight = (DbWeight::get().write * len).saturating_add(len.saturating_mul(600_000));
+	let weight = SystemCall::set_storage::<Runtime>(storage_items).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_system_remark_is_correct() {
+	// #[weight = 700_000]
+	let expected_weight = 700_000;
+	let weight = SystemCall::remark::<Runtime>(vec![]).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_session_set_keys_is_correct() {
+	// #[weight = 200_000_000
+	// 	+ T::DbWeight::get().reads(2 + T::Keys::key_ids().len() as Weight)
+	// 	+ T::DbWeight::get().writes(1 + T::Keys::key_ids().len() as Weight)]
+	//
+	// Polkadot has five possible session keys, so we default to key_ids.len() = 5
+	let expected_weight = 200_000_000 + (DbWeight::get().read * (2 + 5)) + (DbWeight::get().write * (1 + 5));
+	let weight = SessionCall::set_keys::<Runtime>(Default::default(), Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_session_purge_keys_is_correct() {
+	// #[weight = 120_000_000
+	// 	+ T::DbWeight::get().reads_writes(2, 1 + T::Keys::key_ids().len() as Weight)]
+	//
+	// Polkadot has five possible session keys, so we default to key_ids.len() = 5
+	let expected_weight = 120_000_000 + (DbWeight::get().read * 2) + (DbWeight::get().write * (1 + 5));
+	let weight = SessionCall::purge_keys::<Runtime>().get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_democracy_propose_is_correct() {
+	// #[weight = 50_000_000 + T::DbWeight::get().reads_writes(2, 3)]
+	let expected_weight = 50_000_000 + (DbWeight::get().read * 2) + (DbWeight::get().write * 3);
+	let weight = DemocracyCall::propose::<Runtime>(Default::default(), Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_democracy_vote_is_correct() {
+	use democracy::AccountVote;
+	let vote = AccountVote::Standard { vote: Default::default(), balance: Default::default() };
+
+	// #[weight = 50_000_000 + 350_000 * Weight::from(T::MaxVotes::get()) + T::DbWeight::get().reads_writes(3, 3)]
+	let expected_weight = 50_000_000
+		+ 350_000 * (Weight::from(polkadot_runtime::MaxVotes::get()))
+		+ (DbWeight::get().read * 3)
+		+ (DbWeight::get().write * 3);
+	let weight = DemocracyCall::vote::<Runtime>(Default::default(), vote).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_democracy_enact_proposal_is_correct() {
+	// #[weight = T::MaximumBlockWeight::get()]
+	let expected_weight = MaximumBlockWeight::get();
+	let weight =
+		DemocracyCall::enact_proposal::<Runtime>(Default::default(), Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_phragmen_vote_is_correct() {
+	// #[weight = 100_000_000]
+	let expected_weight = 100_000_000;
+	let weight = PhragmenCall::vote::<Runtime>(Default::default(), Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_phragmen_submit_candidacy_is_correct() {
+	// #[weight = 500_000_000]
+	let expected_weight = 500_000_000;
+	let weight = PhragmenCall::submit_candidacy::<Runtime>().get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_phragmen_renounce_candidacy_is_correct() {
+	// #[weight = (2_000_000_000, DispatchClass::Operational)]
+	let expected_weight = 2_000_000_000;
+	let weight = PhragmenCall::renounce_candidacy::<Runtime>().get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_treasury_propose_spend_is_correct() {
+	// #[weight = 120_000_000 + T::DbWeight::get().reads_writes(1, 2)]
+	let expected_weight = 120_000_000 + DbWeight::get().read + 2 * DbWeight::get().write;
+	let weight =
+		TreasuryCall::propose_spend::<Runtime>(Default::default(), Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_treasury_approve_proposal_is_correct() {
+	// #[weight = (34_000_000 + T::DbWeight::get().reads_writes(2, 1), DispatchClass::Operational)]
+	let expected_weight = 34_000_000 + 2 * DbWeight::get().read + DbWeight::get().write;
+	let weight = TreasuryCall::approve_proposal::<Runtime>(Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}
+
+#[test]
+fn weight_of_treasury_tip_is_correct() {
+	let max_len: Weight = <Runtime as treasury::Trait>::Tippers::max_len() as Weight;
+
+	// #[weight = 68_000_000 + 2_000_000 * T::Tippers::max_len() as Weight
+	// 	+ T::DbWeight::get().reads_writes(2, 1)]
+	let expected_weight = 68_000_000 + 2_000_000 * max_len + 2 * DbWeight::get().read + DbWeight::get().write;
+	let weight = TreasuryCall::tip::<Runtime>(Default::default(), Default::default()).get_dispatch_info().weight;
+
+	assert_eq!(weight, expected_weight);
+}