diff --git a/src/cards.css b/src/cards.css
index c3a7a58..f389937 100644
--- a/src/cards.css
+++ b/src/cards.css
@@ -10,7 +10,7 @@
 }
 @media (orientation: portrait) {
   .mbox {
-    padding: 0 calc(.5 * var(--gap));
+    padding: 0 var(--gap-half);
   }
 }
 .mbox:last-child {
diff --git a/src/form.css b/src/form.css
index 5a0151b..ac76cda 100644
--- a/src/form.css
+++ b/src/form.css
@@ -43,6 +43,7 @@ label {
   transition: background-color var(--transition-duration);
 }
 
+input[type="number"],
 input[type="password"],
 input[type="text"],
 input[type="url"],
@@ -54,6 +55,7 @@ textarea {
   margin: 0 0 1.2rem 0;
   padding: var(--padding);
 }
+input[type="number"]:focus,
 input[type="password"]:focus,
 input[type="text"]:focus,
 input[type="url"]:focus,
@@ -169,11 +171,13 @@ button:disabled {
   margin-left: var(--gap);
 }
 .form-inline button,
+.form-inline input[type="number"],
 .form-inline input[type="text"],
 .form-inline textarea {
   margin: .4rem 0;
 }
 
+.form-inline input[type="number"],
 .form-inline input[type="text"],
 .form-inline textarea {
   flex-basis: 50%;
@@ -187,6 +191,46 @@ button:disabled {
   flex-grow: 0;
 }
 
+label.number {
+  display: flex;
+  flex-direction: row;
+  flex-wrap: nowrap;
+  gap: var(--gap);
+  padding: 0;
+}
+* + label.number {
+  margin: var(--gap) 0 0 0;
+}
+label.number span {
+  flex-grow: 1;
+  padding: 0 0 0 var(--padding);
+}
+label.number input[type="number"] {
+  align-self: baseline;
+  margin-bottom: 0;
+}
+@media (orientation: landscape) {
+  label.number span {
+    align-self: center;
+  }
+  label.number input[type="number"] + span {
+    padding: 0 var(--padding) 0 0;
+  }
+}
+@media (orientation: portrait) {
+  label.number {
+    flex-direction: column;
+    gap: var(--gap-half);
+    padding: 0;
+  }
+  label.number span {
+    padding: 0 var(--padding);
+  }
+  label.number input[type="number"] {
+    align-self: stretch;
+  }
+}
+
 button#publish {
   align-self: end;
   order: 2;
diff --git a/src/index.html b/src/index.html
index 68246ac..31493a0 100644
--- a/src/index.html
+++ b/src/index.html
@@ -83,6 +83,27 @@
               <button type="submit" name="publish" tabindex="0" disabled>publish</button>
             </div>
           </form>
+          <form action="#" name="options">
+            <label class="number" for="miningTarget">
+              <span>
+                mining difficulty<br>
+                <small>
+                  with which difficulty to try to mine a proof of work when publishing events, such as: notes, replies, reactions and profile updates.
+                  use zero to disable mining.
+                  difficulty is defined as the number of leading zero bits, read more about
+                  <a href="https://github.com/nostr-protocol/nips/blob/master/13.md" target="_blank" rel="noopener noreferrer">proof of work (nip-13)</a>.
+                </small>
+              </span>
+              <input type="number" name="mining_target" step="1" min="0" max="256" id="miningTarget" value="16">
+            </label>
+            <label class="number" for="miningTimeout">
+              <span>
+                mining timeout<br>
+                <small>abort trying to find a proof if timeout (in seconds) exceeds. use 0 to mine without a time limit.</small>
+              </span>
+              <input type="number" name="mining_timeout" step="1" min="0" max="256" id="miningTimeout" value="5">
+            </label>
+          </form>
           <form action="#" name="settings" autocomplete="new-password">
             <label for="pubkey">public-key</label>
             <input type="text" id="pubkey" autocomplete="off">
diff --git a/src/main.css b/src/main.css
index 01e10b9..11d7024 100644
--- a/src/main.css
+++ b/src/main.css
@@ -15,6 +15,7 @@
   --focus-outline: var(--focus-outline-width) var(--focus-outline-style) var(--focus-outline-color);
   --font-small: 1.2rem;
   --gap: 2.4rem;
+  --gap-half: 1.2rem;
   --max-width: 96ch;
 }
 
diff --git a/src/main.js b/src/main.js
index 31beb96..6cbd997 100644
--- a/src/main.js
+++ b/src/main.js
@@ -40,10 +40,6 @@ let pubkey = localStorage.getItem('pub_key') || (() => {
   return pubkey;
 })();
 
-// arbitrary difficulty, still experimenting.
-// measured empirically, takes N sec on average to mine a text note event.
-const difficulty = 16;
-
 const subList = [];
 const unSubAll = () => {
   subList.forEach(sub => sub.unsub());
@@ -756,6 +752,23 @@ function hideNewMessage(hide) {
   newMessageDiv.hidden = hide;
 }
 
+// arbitrary difficulty default, still experimenting.
+let difficulty = JSON.parse(localStorage.getItem('mining_target')) ?? 16;
+const miningTargetInput = document.querySelector('#miningTarget');
+miningTargetInput.addEventListener('input', (e) => {
+  localStorage.setItem('mining_target', miningTargetInput.valueAsNumber);
+  difficulty = miningTargetInput.valueAsNumber;
+});
+miningTargetInput.value = difficulty;
+
+let timeout = JSON.parse(localStorage.getItem('mining_timeout')) ?? 5;
+const miningTimeoutInput = document.querySelector('#miningTimeout');
+miningTimeoutInput.addEventListener('input', (e) => {
+  localStorage.setItem('mining_timeout', miningTimeoutInput.valueAsNumber);
+  timeout = miningTimeoutInput.valueAsNumber;
+});
+miningTimeoutInput.value = timeout;
+
 async function upvote(eventId, eventPubkey) {
   const privatekey = localStorage.getItem('private_key');
   const note = replyList.find(r => r.id === eventId) || textNoteList.find(n => n.id === (eventId));
@@ -771,7 +784,7 @@ async function upvote(eventId, eventPubkey) {
     content: '+',
     tags,
     created_at: Math.floor(Date.now() * 0.001),
-  }, difficulty, 10).catch(console.warn);
+  }, difficulty, timeout).catch(console.warn);
   if (newReaction) {
     const sig = await signEvent(newReaction, privatekey).catch(console.error);
     if (sig) {
@@ -810,7 +823,7 @@ writeForm.addEventListener('submit', async (e) => {
     pubkey,
     tags,
     created_at: Math.floor(Date.now() * 0.001),
-  }, difficulty, 10).catch(console.warn);
+  }, difficulty, timeout).catch(console.warn);
   if (newEvent) {
     const sig = await signEvent(newEvent, privatekey).catch(onSendError);
     if (sig) {
@@ -954,7 +967,7 @@ profileForm.addEventListener('submit', async (e) => {
     content: JSON.stringify(Object.fromEntries(form)),
     tags: [],
     created_at: Math.floor(Date.now() * 0.001),
-  }, difficulty, 10).catch(console.warn);
+  }, difficulty, timeout).catch(console.warn);
   if (newProfile) {
     const sig = await signEvent(newProfile, privatekey).catch(console.error);
     if (sig) {
@@ -1031,8 +1044,12 @@ function validatePow(evt) {
  *
  * powEvent returns a rejected promise if the funtion runs for longer than timeout.
  * a zero timeout makes mineEvent run without a time limit.
+ * a zero mining target just resolves the promise without trying to find a 'nonce'.
  */
-function powEvent(evt, difficulty, timeout = 0) {
+function powEvent(evt, difficulty, timeout) {
+  if (difficulty === 0) {
+    return Promise.resolve(evt);
+  }
   return new Promise((resolve, reject) => {
     const worker = new Worker('./worker.js');
 
diff --git a/src/tabs.css b/src/tabs.css
index 39cf5ec..9938ecc 100644
--- a/src/tabs.css
+++ b/src/tabs.css
@@ -45,7 +45,7 @@ input[type="radio"]:checked + label {
 .tab-content {
   max-width: var(--max-width);
   min-height: 200px;
-  padding: calc(.5 * var(--gap)) 0 100px 0;
+  padding: var(--gap-half) 0 100px 0;
 }
 .tabbed {
   align-items: start;